[PATCH v3 0/9] kexec_file_load implementation for PowerPC

[PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Thiago Jung Bauermann]

Hello,

This patch series implements the kexec_file_load system call on PowerPC.

This system call moves the reading of the kernel, initrd and the device tree
from the userspace kexec tool to the kernel. This is needed if you want to
do one or both of the following:

1. only allow loading of signed kernels.
2. "measure" (i.e., record the hashes of) the kernel, initrd, kernel
   command line and other boot inputs for the Integrity Measurement
   Architecture subsystem.

The above are the functions kexec already has built into kexec_file_load.
Yesterday I posted a set of patches which allows a third feature:

3. have IMA pass-on its event log (where integrity measurements are
   registered) accross kexec to the second kernel, so that the event
   history is preserved.

Because OpenPower uses an intermediary Linux instance as a boot loader
(skiroot), feature 1 is needed to implement secure boot for the platform,
while features 2 and 3 are needed to implement trusted boot.

This patch series starts by removing an x86 assumption from kexec_file:
kexec_add_buffer uses iomem to find reserved memory ranges, but PowerPC
uses the memblock subsystem.  A hook is added so that each arch can
specify how memory ranges can be found.

Also, the memory-walking logic in kexec_add_buffer is useful in this
implementation to find a free area for the purgatory's stack, so the
next patch moves that logic to kexec_locate_mem_hole.

The kexec_file_load system call needs to apply relocations to the
purgatory but adding code for that would duplicate functionality with
the module loading mechanism, which also needs to apply relocations to
the kernel modules.  Therefore, this patch series factors out the module
relocation code so that it can be shared.

One thing that is still missing is crashkernel support, which I intend
to submit shortly. For now, arch_kexec_kernel_image_probe rejects crash
kernels.

This code is based on kexec-tools, but with many modifications to adapt
it to the kernel environment and facilities. Except the purgatory,
which only has minimal changes.

Changes for v3:
- Rebased series on today's powerpc/next.
- Patch "kexec_file: Generalize kexec_add_buffer.":
    - Removed most arguments from arch_kexec_walk_mem and pass kbuf
      explicitly.
- Patch "powerpc: Add functions to read ELF files of any endianness.":
    - Fixed whitespace issues found by checkpatch.pl.
- Patch "powerpc: Factor out relocation code from module_64.c to
  elf_util_64.c.":
    - Changed to use the new PPC64_ELF_ABI_v2 macro.
- Patch "powerpc: Add support for loading ELF kernels with
  kexec_file_load.":
    - Adapted arch_kexec_walk_mem implementation to changes in its
      argument list.
    - Fixed whitespace and GPL header issues found by checkpatch.pl.
- Patch "powerpc: Add purgatory for kexec_file_load implementation.":
    - Fixed whitespace and GPL header issues found by checkpatch.pl.
    - Changed to use the new PPC64_ELF_ABI_v2 macro.

Changes for v2:

- All patches: forgot to add Signed-off-by lines in v1, so added them now.
- Patch "kexec_file: Generalize kexec_add_buffer.": broke in two, one
  adding arch_kexec_walk_mem and the other adding kexec_locate_mem_hole.
- Patch "powerpc: Implement kexec_file_load.":
    - Moved relocation changes and the arch_kexec_walk_mem implementation
      to the next patch in the series.
    - Removed pr_fmt from machine_kexec_64.c, since the patch doesn't add
      any call to pr_debug in that file.
    - Changed arch_kexec_kernel_image_probe to reject crash kernels.

Changes for v3:
- Rebased series on today's powerpc/next.
- Patch "kexec_file: Generalize kexec_add_buffer.":
    - Removed most arguments from arch_kexec_walk_mem and pass kbuf
      explicitly.
- Patch "powerpc: Add functions to read ELF files of any endianness.":
    - Fixed whitespace issues found by checkpatch.pl.
- Patch "powerpc: Factor out relocation code from module_64.c to
  elf_util_64.c.":
    - Changed to use the new PPC64_ELF_ABI_v2 macro.
- Patch "powerpc: Add support for loading ELF kernels with
  kexec_file_load.":
    - Adapted arch_kexec_walk_mem implementation to changes in its
      argument list.
    - Fixed whitespace and GPL header issues found by checkpatch.pl.
- Patch "powerpc: Add purgatory for kexec_file_load implementation.":
    - Fixed whitespace and GPL header issues found by checkpatch.pl.
    - Changed to use the new PPC64_ELF_ABI_v2 macro.

Changes for v2:

- All patches: forgot to add Signed-off-by lines in v1, so added them now.
- Patch "kexec_file: Generalize kexec_add_buffer.": broke in two, one
  adding arch_kexec_walk_mem and the other adding kexec_locate_mem_hole.
- Patch "powerpc: Implement kexec_file_load.":
    - Moved relocation changes and the arch_kexec_walk_mem implementation
      to the next patch in the series.
    - Removed pr_fmt from machine_kexec_64.c, since the patch doesn't add
      any call to pr_debug in that file.
    - Changed arch_kexec_kernel_image_probe to reject crash kernels.

Thiago Jung Bauermann (9):
  kexec_file: Remove unused members from struct kexec_buf.
  kexec_file: Generalize kexec_add_buffer.
  kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.
  powerpc: Factor out relocation code from module_64.c to elf_util_64.c.
  powerpc: Generalize elf64_apply_relocate_add.
  powerpc: Add functions to read ELF files of any endianness.
  powerpc: Implement kexec_file_load.
  powerpc: Add support for loading ELF kernels with kexec_file_load.
  powerpc: Add purgatory for kexec_file_load implementation.

 arch/powerpc/Kconfig                      |  13 +
 arch/powerpc/Makefile                     |   4 +
 arch/powerpc/include/asm/elf_util.h       |  92 +++++
 arch/powerpc/include/asm/kexec_elf_64.h   |  10 +
 arch/powerpc/include/asm/module.h         |  14 +-
 arch/powerpc/include/asm/systbl.h         |   1 +
 arch/powerpc/include/asm/unistd.h         |   2 +-
 arch/powerpc/include/uapi/asm/unistd.h    |   1 +
 arch/powerpc/kernel/Makefile              |   7 +
 arch/powerpc/kernel/elf_util.c            | 476 +++++++++++++++++++++++++
 arch/powerpc/kernel/elf_util_64.c         | 374 ++++++++++++++++++++
 arch/powerpc/kernel/kexec_elf_64.c        | 560 ++++++++++++++++++++++++++++++
 arch/powerpc/kernel/machine_kexec_64.c    | 134 +++++++
 arch/powerpc/kernel/module_64.c           | 328 +++--------------
 arch/powerpc/purgatory/.gitignore         |   2 +
 arch/powerpc/purgatory/Makefile           |  36 ++
 arch/powerpc/purgatory/console-ppc64.c    |  38 ++
 arch/powerpc/purgatory/crashdump-ppc64.h  |  42 +++
 arch/powerpc/purgatory/crashdump_backup.c |  36 ++
 arch/powerpc/purgatory/crtsavres.S        |   5 +
 arch/powerpc/purgatory/hvCall.S           |  27 ++
 arch/powerpc/purgatory/hvCall.h           |   8 +
 arch/powerpc/purgatory/kexec-sha256.h     |  11 +
 arch/powerpc/purgatory/ppc64_asm.h        |  20 ++
 arch/powerpc/purgatory/printf.c           | 164 +++++++++
 arch/powerpc/purgatory/purgatory-ppc64.c  |  41 +++
 arch/powerpc/purgatory/purgatory-ppc64.h  |   6 +
 arch/powerpc/purgatory/purgatory.c        |  62 ++++
 arch/powerpc/purgatory/purgatory.h        |  11 +
 arch/powerpc/purgatory/sha256.c           |   6 +
 arch/powerpc/purgatory/sha256.h           |   1 +
 arch/powerpc/purgatory/string.S           |   1 +
 arch/powerpc/purgatory/v2wrap.S           | 134 +++++++
 include/linux/kexec.h                     |  23 +-
 kernel/kexec_file.c                       | 100 ++++--
 kernel/kexec_internal.h                   |  16 -
 36 files changed, 2476 insertions(+), 330 deletions(-)
 create mode 100644 arch/powerpc/include/asm/elf_util.h
 create mode 100644 arch/powerpc/include/asm/kexec_elf_64.h
 create mode 100644 arch/powerpc/kernel/elf_util.c
 create mode 100644 arch/powerpc/kernel/elf_util_64.c
 create mode 100644 arch/powerpc/kernel/kexec_elf_64.c
 create mode 100644 arch/powerpc/purgatory/.gitignore
 create mode 100644 arch/powerpc/purgatory/Makefile
 create mode 100644 arch/powerpc/purgatory/console-ppc64.c
 create mode 100644 arch/powerpc/purgatory/crashdump-ppc64.h
 create mode 100644 arch/powerpc/purgatory/crashdump_backup.c
 create mode 100644 arch/powerpc/purgatory/crtsavres.S
 create mode 100644 arch/powerpc/purgatory/hvCall.S
 create mode 100644 arch/powerpc/purgatory/hvCall.h
 create mode 100644 arch/powerpc/purgatory/kexec-sha256.h
 create mode 100644 arch/powerpc/purgatory/ppc64_asm.h
 create mode 100644 arch/powerpc/purgatory/printf.c
 create mode 100644 arch/powerpc/purgatory/purgatory-ppc64.c
 create mode 100644 arch/powerpc/purgatory/purgatory-ppc64.h
 create mode 100644 arch/powerpc/purgatory/purgatory.c
 create mode 100644 arch/powerpc/purgatory/purgatory.h
 create mode 100644 arch/powerpc/purgatory/sha256.c
 create mode 100644 arch/powerpc/purgatory/sha256.h
 create mode 100644 arch/powerpc/purgatory/string.S
 create mode 100644 arch/powerpc/purgatory/v2wrap.S

-- 
1.9.1

[PATCH v3 1/9] kexec_file: Remove unused members from struct kexec_buf.

[Thiago Jung Bauermann]

kexec_add_buffer uses kexec_buf.buffer and kexec_buf.bufsz to pass along
its own arguments buffer and bufsz, but since they aren't used anywhere
else, it's pointless.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Dave Young <dyoung@redhat.com>
---
 kernel/kexec_file.c     | 6 ++----
 kernel/kexec_internal.h | 2 --
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 01ab82a40d22..b6eec7527e9f 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -464,8 +464,6 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	memset(&buf, 0, sizeof(struct kexec_buf));
 	kbuf = &buf;
 	kbuf->image = image;
-	kbuf->buffer = buffer;
-	kbuf->bufsz = bufsz;
 
 	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
 	kbuf->buf_align = max(buf_align, PAGE_SIZE);
@@ -489,8 +487,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
-	ksegment->kbuf = kbuf->buffer;
-	ksegment->bufsz = kbuf->bufsz;
+	ksegment->kbuf = buffer;
+	ksegment->bufsz = bufsz;
 	ksegment->mem = kbuf->mem;
 	ksegment->memsz = kbuf->memsz;
 	image->nr_segments++;
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index 0a52315d9c62..eefd5bf960c2 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -26,8 +26,6 @@ struct kexec_sha_region {
  */
 struct kexec_buf {
 	struct kimage *image;
-	char *buffer;
-	unsigned long bufsz;
 	unsigned long mem;
 	unsigned long memsz;
 	unsigned long buf_align;
-- 
1.9.1

[PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Allow architectures to specify different memory walking functions for
kexec_add_buffer. Intel uses iomem to track reserved memory ranges,
but PowerPC uses the memblock subsystem.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h   | 19 ++++++++++++++++++-
 kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
 kernel/kexec_internal.h | 14 --------------
 3 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e8acb2b43dd9..3d91bcfc180d 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -146,7 +146,24 @@ struct kexec_file_ops {
 	kexec_verify_sig_t *verify_sig;
 #endif
 };
-#endif
+
+/*
+ * Keeps track of buffer parameters as provided by caller for requesting
+ * memory placement of buffer.
+ */
+struct kexec_buf {
+	struct kimage *image;
+	unsigned long mem;
+	unsigned long memsz;
+	unsigned long buf_align;
+	unsigned long buf_min;
+	unsigned long buf_max;
+	bool top_down;		/* allocate from top of memory hole */
+};
+
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *));
+#endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
 	kimage_entry_t head;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b6eec7527e9f..b1f1f6402518 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 	return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
+/**
+ * arch_kexec_walk_mem - call func(data) on free memory regions
+ * @kbuf:	Context info for the search. Also passed to @func.
+ * @func:	Function to call for each memory region.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *))
+{
+	if (kbuf->image->type == KEXEC_TYPE_CRASH)
+		return walk_iomem_res_desc(crashk_res.desc,
+					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+					   crashk_res.start, crashk_res.end,
+					   kbuf, func);
+	else
+		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	if (image->type == KEXEC_TYPE_CRASH)
-		ret = walk_iomem_res_desc(crashk_res.desc,
-				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
-				crashk_res.start, crashk_res.end, kbuf,
-				locate_mem_hole_callback);
-	else
-		ret = walk_system_ram_res(0, -1, kbuf,
-					  locate_mem_hole_callback);
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
 	if (ret != 1) {
 		/* A suitable memory range could not be found for buffer */
 		return -EADDRNOTAVAIL;
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index eefd5bf960c2..4cef7e4706b0 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -20,20 +20,6 @@ struct kexec_sha_region {
 	unsigned long len;
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
- */
-struct kexec_buf {
-	struct kimage *image;
-	unsigned long mem;
-	unsigned long memsz;
-	unsigned long buf_align;
-	unsigned long buf_min;
-	unsigned long buf_max;
-	bool top_down;		/* allocate from top of memory hole */
-};
-
 void kimage_file_post_load_cleanup(struct kimage *image);
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
-- 
1.9.1

[PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h |  4 ++++
 kernel/kexec_file.c   | 66 ++++++++++++++++++++++++++++++++++++++-------------
 2 files changed, 53 insertions(+), 17 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 3d91bcfc180d..4ca6f5f95d66 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -227,6 +227,10 @@ extern asmlinkage long sys_kexec_load(unsigned long entry,
 					struct kexec_segment __user *segments,
 					unsigned long flags);
 extern int kernel_kexec(void);
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr);
 extern int kexec_add_buffer(struct kimage *image, char *buffer,
 			    unsigned long bufsz, unsigned long memsz,
 			    unsigned long buf_align, unsigned long buf_min,
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b1f1f6402518..85a515511925 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -449,6 +449,46 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @image:	kexec image being updated.
+ * @size:	Memory size.
+ * @align:	Minimum alignment needed.
+ * @min_addr:	Minimum starting address.
+ * @max_addr:	Maximum end address.
+ * @top_down	Find the highest free memory region?
+ * @addr	On success, will have start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
+			  unsigned long align, unsigned long min_addr,
+			  unsigned long max_addr, bool top_down,
+			  unsigned long *addr)
+{
+	int ret;
+	struct kexec_buf buf;
+
+	memset(&buf, 0, sizeof(struct kexec_buf));
+	buf.image = image;
+
+	buf.memsz = size;
+	buf.buf_align = align;
+	buf.buf_min = min_addr;
+	buf.buf_max = max_addr;
+	buf.top_down = top_down;
+
+	ret = arch_kexec_walk_mem(&buf, locate_mem_hole_callback);
+	if (ret != 1) {
+		/* A suitable memory range could not be found for buffer */
+		return -EADDRNOTAVAIL;
+	}
+
+	*addr = buf.mem;
+
+	return 0;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -460,8 +500,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 {
 
 	struct kexec_segment *ksegment;
-	struct kexec_buf buf, *kbuf;
 	int ret;
+	unsigned long addr, align, size;
 
 	/* Currently adding segment this way is allowed only in file mode */
 	if (!image->file_mode)
@@ -482,29 +522,21 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 		return -EINVAL;
 	}
 
-	memset(&buf, 0, sizeof(struct kexec_buf));
-	kbuf = &buf;
-	kbuf->image = image;
-
-	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
-	kbuf->buf_align = max(buf_align, PAGE_SIZE);
-	kbuf->buf_min = buf_min;
-	kbuf->buf_max = buf_max;
-	kbuf->top_down = top_down;
+	size = ALIGN(memsz, PAGE_SIZE);
+	align = max(buf_align, PAGE_SIZE);
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(image, size, align, buf_min, buf_max,
+				    top_down, &addr);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
 	ksegment->kbuf = buffer;
 	ksegment->bufsz = bufsz;
-	ksegment->mem = kbuf->mem;
-	ksegment->memsz = kbuf->memsz;
+	ksegment->mem = addr;
+	ksegment->memsz = size;
 	image->nr_segments++;
 	*load_addr = ksegment->mem;
 	return 0;
-- 
1.9.1

[PATCH v3 4/9] powerpc: Factor out relocation code from module_64.c to elf_util_64.c.

[Thiago Jung Bauermann]

The kexec_file_load system call needs to relocate the purgatory, so
factor out the module relocation code so that it can be shared.

This patch's purpose is to move the ELF relocation logic from
apply_relocate_add to elf_util_64.c with as few changes as
possible. The following changes were needed:

To avoid having module-specific code in a general purpose utility
function, struct elf_info was created to contain the information
needed for ELF binaries manipulation.

my_r2, stub_for_addr and create_stub were changed to use it instead of
having to receive a struct module, since they are called from
elf64_apply_relocate_add.

local_entry_offset and squash_toc_save_inst were only used by
apply_rellocate_add, so they were moved to elf_util_64.c as well.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Torsten Duwe <duwe@suse.de>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/include/asm/elf_util.h |  70 ++++++++
 arch/powerpc/include/asm/module.h   |  14 +-
 arch/powerpc/kernel/Makefile        |   4 +
 arch/powerpc/kernel/elf_util_64.c   | 269 +++++++++++++++++++++++++++++++
 arch/powerpc/kernel/module_64.c     | 312 ++++--------------------------------
 5 files changed, 386 insertions(+), 283 deletions(-)

diff --git a/arch/powerpc/include/asm/elf_util.h b/arch/powerpc/include/asm/elf_util.h
new file mode 100644
index 000000000000..37372559fe62
--- /dev/null
+++ b/arch/powerpc/include/asm/elf_util.h
@@ -0,0 +1,70 @@
+/*
+ * Utility functions to work with ELF files.
+ *
+ * Copyright (C) 2016, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _ASM_POWERPC_ELF_UTIL_H
+#define _ASM_POWERPC_ELF_UTIL_H
+
+#include <linux/elf.h>
+
+struct elf_info {
+	struct elf_shdr *sechdrs;
+
+	/* Index of stubs section. */
+	unsigned int stubs_section;
+	/* Index of TOC section. */
+	unsigned int toc_section;
+};
+
+#ifdef __powerpc64__
+#ifdef PPC64_ELF_ABI_v2
+
+/* An address is simply the address of the function. */
+typedef unsigned long func_desc_t;
+#else
+
+/* An address is address of the OPD entry, which contains address of fn. */
+typedef struct ppc64_opd_entry func_desc_t;
+#endif /* PPC64_ELF_ABI_v2 */
+
+/* Like PPC32, we need little trampolines to do > 24-bit jumps (into
+   the kernel itself).  But on PPC64, these need to be used for every
+   jump, actually, to reset r2 (TOC+0x8000). */
+struct ppc64_stub_entry
+{
+	/* 28 byte jump instruction sequence (7 instructions). We only
+	 * need 6 instructions on ABIv2 but we always allocate 7 so
+	 * so we don't have to modify the trampoline load instruction. */
+	u32 jump[7];
+	/* Used by ftrace to identify stubs */
+	u32 magic;
+	/* Data for the above code */
+	func_desc_t funcdata;
+};
+#endif
+
+/* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
+   gives the value maximum span in an instruction which uses a signed
+   offset) */
+static inline unsigned long my_r2(const struct elf_info *elf_info)
+{
+	return elf_info->sechdrs[elf_info->toc_section].sh_addr + 0x8000;
+}
+
+int elf64_apply_relocate_add(const struct elf_info *elf_info,
+			     const char *strtab, unsigned int symindex,
+			     unsigned int relsec, const char *obj_name);
+
+#endif /* _ASM_POWERPC_ELF_UTIL_H */
diff --git a/arch/powerpc/include/asm/module.h b/arch/powerpc/include/asm/module.h
index cd4ffd86765f..f2073115d518 100644
--- a/arch/powerpc/include/asm/module.h
+++ b/arch/powerpc/include/asm/module.h
@@ -12,7 +12,14 @@
 #include <linux/list.h>
 #include <asm/bug.h>
 #include <asm-generic/module.h>
+#include <asm/elf_util.h>
 
+/* Both low and high 16 bits are added as SIGNED additions, so if low
+   16 bits has high bit set, high 16 bits must be adjusted.  These
+   macros do that (stolen from binutils). */
+#define PPC_LO(v) ((v) & 0xffff)
+#define PPC_HI(v) (((v) >> 16) & 0xffff)
+#define PPC_HA(v) PPC_HI ((v) + 0x8000)
 
 #ifndef __powerpc64__
 /*
@@ -33,8 +40,7 @@ struct ppc_plt_entry {
 
 struct mod_arch_specific {
 #ifdef __powerpc64__
-	unsigned int stubs_section;	/* Index of stubs section in module */
-	unsigned int toc_section;	/* What section is the TOC? */
+	struct elf_info elf_info;
 	bool toc_fixed;			/* Have we fixed up .TOC.? */
 #ifdef CONFIG_DYNAMIC_FTRACE
 	unsigned long toc;
@@ -90,6 +96,10 @@ static inline int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sec
 }
 #endif
 
+unsigned long stub_for_addr(const struct elf_info *elf_info, unsigned long addr,
+			    const char *obj_name);
+int restore_r2(u32 *instruction, const char *obj_name);
+
 struct exception_table_entry;
 void sort_ex_table(struct exception_table_entry *start,
 		   struct exception_table_entry *finish);
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 2da380fcc34c..e99f626acc85 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -124,6 +124,10 @@ ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)
 obj-y				+= iomap.o
 endif
 
+ifeq ($(CONFIG_MODULES)$(CONFIG_WORD_SIZE),y64)
+obj-y				+= elf_util_64.o
+endif
+
 obj64-$(CONFIG_PPC_TRANSACTIONAL_MEM)	+= tm.o
 
 obj-$(CONFIG_PPC64)		+= $(obj64-y)
diff --git a/arch/powerpc/kernel/elf_util_64.c b/arch/powerpc/kernel/elf_util_64.c
new file mode 100644
index 000000000000..decad2c34f38
--- /dev/null
+++ b/arch/powerpc/kernel/elf_util_64.c
@@ -0,0 +1,269 @@
+/*
+ * Utility functions to work with ELF files.
+ *
+ * Copyright (C) 2016, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <asm/ppc-opcode.h>
+#include <asm/elf_util.h>
+
+/*
+ * We just need to use the functions defined in <asm/module.h>, so just declare
+ * struct module here and avoid having to import <linux/module.h>.
+ */
+struct module;
+#include <asm/module.h>
+
+#ifdef PPC64_ELF_ABI_v2
+/* PowerPC64 specific values for the Elf64_Sym st_other field.  */
+#define STO_PPC64_LOCAL_BIT	5
+#define STO_PPC64_LOCAL_MASK	(7 << STO_PPC64_LOCAL_BIT)
+#define PPC64_LOCAL_ENTRY_OFFSET(other)					\
+ (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
+
+static unsigned int local_entry_offset(const Elf64_Sym *sym)
+{
+	/* sym->st_other indicates offset to local entry point
+	 * (otherwise it will assume r12 is the address of the start
+	 * of function and try to derive r2 from it). */
+	return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
+}
+#else
+static unsigned int local_entry_offset(const Elf64_Sym *sym)
+{
+	return 0;
+}
+#endif
+
+#ifdef CC_USING_MPROFILE_KERNEL
+/*
+ * In case of _mcount calls, do not save the current callee's TOC (in r2) into
+ * the original caller's stack frame. If we did we would clobber the saved TOC
+ * value of the original caller.
+ */
+static void squash_toc_save_inst(const char *name, unsigned long addr)
+{
+	struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr;
+
+	/* Only for calls to _mcount */
+	if (strcmp("_mcount", name) != 0)
+		return;
+
+	stub->jump[2] = PPC_INST_NOP;
+}
+#else
+static void squash_toc_save_inst(const char *name, unsigned long addr) { }
+#endif
+
+/**
+ * elf64_apply_relocate_add - apply 64 bit RELA relocations
+ * @elf_info:		Support information for the ELF binary being relocated.
+ * @strtab:		String table for the associated symbol table.
+ * @symindex:		Section header index for the associated symbol table.
+ * @relsec:		Section header index for the relocations to apply.
+ * @obj_name:		The name of the ELF binary, for information messages.
+ */
+int elf64_apply_relocate_add(const struct elf_info *elf_info,
+			     const char *strtab, unsigned int symindex,
+			     unsigned int relsec, const char *obj_name)
+{
+	unsigned int i;
+	Elf64_Shdr *sechdrs = elf_info->sechdrs;
+	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
+	Elf64_Sym *sym;
+	unsigned long *location;
+	unsigned long value;
+
+
+	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
+		/* This is where to make the change */
+		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+			+ rela[i].r_offset;
+		/* This is the symbol it is referring to */
+		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
+			+ ELF64_R_SYM(rela[i].r_info);
+
+		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
+		       location, (long)ELF64_R_TYPE(rela[i].r_info),
+		       strtab + sym->st_name, (unsigned long)sym->st_value,
+		       (long)rela[i].r_addend);
+
+		/* `Everything is relative'. */
+		value = sym->st_value + rela[i].r_addend;
+
+		switch (ELF64_R_TYPE(rela[i].r_info)) {
+		case R_PPC64_ADDR32:
+			/* Simply set it */
+			*(u32 *)location = value;
+			break;
+
+		case R_PPC64_ADDR64:
+			/* Simply set it */
+			*(unsigned long *)location = value;
+			break;
+
+		case R_PPC64_TOC:
+			*(unsigned long *)location = my_r2(elf_info);
+			break;
+
+		case R_PPC64_TOC16:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			if (value + 0x8000 > 0xffff) {
+				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
+				       obj_name, value);
+				return -ENOEXEC;
+			}
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+			break;
+
+		case R_PPC64_TOC16_LO:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+			break;
+
+		case R_PPC64_TOC16_DS:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
+				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
+				       obj_name, value);
+				return -ENOEXEC;
+			}
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xfffc)
+				| (value & 0xfffc);
+			break;
+
+		case R_PPC64_TOC16_LO_DS:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			if ((value & 3) != 0) {
+				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
+				       obj_name, value);
+				return -ENOEXEC;
+			}
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xfffc)
+				| (value & 0xfffc);
+			break;
+
+		case R_PPC64_TOC16_HA:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			value = ((value + 0x8000) >> 16);
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+			break;
+
+		case R_PPC_REL24:
+			/* FIXME: Handle weak symbols here --RR */
+			if (sym->st_shndx == SHN_UNDEF) {
+				/* External: go via stub */
+				value = stub_for_addr(elf_info, value, obj_name);
+				if (!value)
+					return -ENOENT;
+				if (!restore_r2((u32 *)location + 1, obj_name))
+					return -ENOEXEC;
+
+				squash_toc_save_inst(strtab + sym->st_name, value);
+			} else
+				value += local_entry_offset(sym);
+
+			/* Convert value to relative */
+			value -= (unsigned long)location;
+			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
+				pr_err("%s: REL24 %li out of range!\n",
+				       obj_name, (long int)value);
+				return -ENOEXEC;
+			}
+
+			/* Only replace bits 2 through 26 */
+			*(uint32_t *)location
+				= (*(uint32_t *)location & ~0x03fffffc)
+				| (value & 0x03fffffc);
+			break;
+
+		case R_PPC64_REL64:
+			/* 64 bits relative (used by features fixups) */
+			*location = value - (unsigned long)location;
+			break;
+
+		case R_PPC64_TOCSAVE:
+			/*
+			 * Marker reloc indicates we don't have to save r2.
+			 * That would only save us one instruction, so ignore
+			 * it.
+			 */
+			break;
+
+		case R_PPC64_ENTRY:
+			/*
+			 * Optimize ELFv2 large code model entry point if
+			 * the TOC is within 2GB range of current location.
+			 */
+			value = my_r2(elf_info) - (unsigned long)location;
+			if (value + 0x80008000 > 0xffffffff)
+				break;
+			/*
+			 * Check for the large code model prolog sequence:
+			 *	ld r2, ...(r12)
+			 *	add r2, r2, r12
+			 */
+			if ((((uint32_t *)location)[0] & ~0xfffc)
+			    != 0xe84c0000)
+				break;
+			if (((uint32_t *)location)[1] != 0x7c426214)
+				break;
+			/*
+			 * If found, replace it with:
+			 *	addis r2, r12, (.TOC.-func)@ha
+			 *	addi r2, r12, (.TOC.-func)@l
+			 */
+			((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
+			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
+			break;
+
+		case R_PPC64_REL16_HA:
+			/* Subtract location pointer */
+			value -= (unsigned long)location;
+			value = ((value + 0x8000) >> 16);
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+			break;
+
+		case R_PPC64_REL16_LO:
+			/* Subtract location pointer */
+			value -= (unsigned long)location;
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+			break;
+
+		default:
+			pr_err("%s: Unknown ADD relocation: %lu\n",
+			       obj_name,
+			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
+			return -ENOEXEC;
+		}
+	}
+
+	return 0;
+}
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index f703f343358e..f2b25b4f9066 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -19,7 +19,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/module.h>
-#include <linux/elf.h>
+#include <asm/elf_util.h>
 #include <linux/moduleloader.h>
 #include <linux/err.h>
 #include <linux/vmalloc.h>
@@ -43,9 +43,6 @@
 
 #ifdef PPC64_ELF_ABI_v2
 
-/* An address is simply the address of the function. */
-typedef unsigned long func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
 	return addr;
@@ -58,25 +55,8 @@ static unsigned long stub_func_addr(func_desc_t func)
 {
 	return func;
 }
-
-/* PowerPC64 specific values for the Elf64_Sym st_other field.  */
-#define STO_PPC64_LOCAL_BIT	5
-#define STO_PPC64_LOCAL_MASK	(7 << STO_PPC64_LOCAL_BIT)
-#define PPC64_LOCAL_ENTRY_OFFSET(other)					\
- (((1 << (((other) & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT)) >> 2) << 2)
-
-static unsigned int local_entry_offset(const Elf64_Sym *sym)
-{
-	/* sym->st_other indicates offset to local entry point
-	 * (otherwise it will assume r12 is the address of the start
-	 * of function and try to derive r2 from it). */
-	return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other);
-}
 #else
 
-/* An address is address of the OPD entry, which contains address of fn. */
-typedef struct ppc64_opd_entry func_desc_t;
-
 static func_desc_t func_desc(unsigned long addr)
 {
 	return *(struct ppc64_opd_entry *)addr;
@@ -89,29 +69,10 @@ static unsigned long stub_func_addr(func_desc_t func)
 {
 	return func.funcaddr;
 }
-static unsigned int local_entry_offset(const Elf64_Sym *sym)
-{
-	return 0;
-}
 #endif
 
 #define STUB_MAGIC 0x73747562 /* stub */
 
-/* Like PPC32, we need little trampolines to do > 24-bit jumps (into
-   the kernel itself).  But on PPC64, these need to be used for every
-   jump, actually, to reset r2 (TOC+0x8000). */
-struct ppc64_stub_entry
-{
-	/* 28 byte jump instruction sequence (7 instructions). We only
-	 * need 6 instructions on ABIv2 but we always allocate 7 so
-	 * so we don't have to modify the trampoline load instruction. */
-	u32 jump[7];
-	/* Used by ftrace to identify stubs */
-	u32 magic;
-	/* Data for the above code */
-	func_desc_t funcdata;
-};
-
 /*
  * PPC64 uses 24 bit jumps, but we need to jump into other modules or
  * the kernel which may be further.  So we jump to a stub.
@@ -346,9 +307,9 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
 	for (i = 1; i < hdr->e_shnum; i++) {
 		char *p;
 		if (strcmp(secstrings + sechdrs[i].sh_name, ".stubs") == 0)
-			me->arch.stubs_section = i;
+			me->arch.elf_info.stubs_section = i;
 		else if (strcmp(secstrings + sechdrs[i].sh_name, ".toc") == 0)
-			me->arch.toc_section = i;
+			me->arch.elf_info.toc_section = i;
 		else if (strcmp(secstrings+sechdrs[i].sh_name,"__versions")==0)
 			dedotify_versions((void *)hdr + sechdrs[i].sh_offset,
 					  sechdrs[i].sh_size);
@@ -364,7 +325,7 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
 				 + sechdrs[sechdrs[i].sh_link].sh_offset);
 	}
 
-	if (!me->arch.stubs_section) {
+	if (!me->arch.elf_info.stubs_section) {
 		pr_err("%s: doesn't contain .stubs.\n", me->name);
 		return -ENOEXEC;
 	}
@@ -373,44 +334,32 @@ int module_frob_arch_sections(Elf64_Ehdr *hdr,
 	   to some reasonable value in case the module calls out to
 	   other functions via a stub, or if a function pointer escapes
 	   the module by some means.  */
-	if (!me->arch.toc_section)
-		me->arch.toc_section = me->arch.stubs_section;
+	if (!me->arch.elf_info.toc_section)
+		me->arch.elf_info.toc_section = me->arch.elf_info.stubs_section;
 
 	/* Override the stubs size */
-	sechdrs[me->arch.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
-	return 0;
-}
+	sechdrs[me->arch.elf_info.stubs_section].sh_size = get_stubs_size(hdr, sechdrs);
 
-/* r2 is the TOC pointer: it actually points 0x8000 into the TOC (this
-   gives the value maximum span in an instruction which uses a signed
-   offset) */
-static inline unsigned long my_r2(const Elf64_Shdr *sechdrs, struct module *me)
-{
-	return sechdrs[me->arch.toc_section].sh_addr + 0x8000;
-}
+	/* For the elf_util functions. */
+	me->arch.elf_info.sechdrs = sechdrs;
 
-/* Both low and high 16 bits are added as SIGNED additions, so if low
-   16 bits has high bit set, high 16 bits must be adjusted.  These
-   macros do that (stolen from binutils). */
-#define PPC_LO(v) ((v) & 0xffff)
-#define PPC_HI(v) (((v) >> 16) & 0xffff)
-#define PPC_HA(v) PPC_HI ((v) + 0x8000)
+	return 0;
+}
 
 /* Patch stub to reference function and correct r2 value. */
-static inline int create_stub(const Elf64_Shdr *sechdrs,
+static inline int create_stub(const struct elf_info *elf_info,
 			      struct ppc64_stub_entry *entry,
-			      unsigned long addr,
-			      struct module *me)
+			      unsigned long addr, const char *obj_name)
 {
 	long reladdr;
 
 	memcpy(entry->jump, ppc64_stub_insns, sizeof(ppc64_stub_insns));
 
 	/* Stub uses address relative to r2. */
-	reladdr = (unsigned long)entry - my_r2(sechdrs, me);
+	reladdr = (unsigned long)entry - my_r2(elf_info);
 	if (reladdr > 0x7FFFFFFF || reladdr < -(0x80000000L)) {
 		pr_err("%s: Address %p of stub out of range of %p.\n",
-		       me->name, (void *)reladdr, (void *)my_r2);
+		       obj_name, (void *)reladdr, (void *)my_r2);
 		return 0;
 	}
 	pr_debug("Stub %p get data from reladdr %li\n", entry, reladdr);
@@ -425,17 +374,17 @@ static inline int create_stub(const Elf64_Shdr *sechdrs,
 
 /* Create stub to jump to function described in this OPD/ptr: we need the
    stub to set up the TOC ptr (r2) for the function. */
-static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
-				   unsigned long addr,
-				   struct module *me)
+unsigned long stub_for_addr(const struct elf_info *elf_info, unsigned long addr,
+			    const char *obj_name)
 {
+	struct elf_shdr *stubs_sec = &elf_info->sechdrs[elf_info->stubs_section];
 	struct ppc64_stub_entry *stubs;
 	unsigned int i, num_stubs;
 
-	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*stubs);
+	num_stubs = stubs_sec->sh_size / sizeof(*stubs);
 
 	/* Find this stub, or if that fails, the next avail. entry */
-	stubs = (void *)sechdrs[me->arch.stubs_section].sh_addr;
+	stubs = (void *) stubs_sec->sh_addr;
 	for (i = 0; stub_func_addr(stubs[i].funcdata); i++) {
 		BUG_ON(i >= num_stubs);
 
@@ -443,7 +392,7 @@ static unsigned long stub_for_addr(const Elf64_Shdr *sechdrs,
 			return (unsigned long)&stubs[i];
 	}
 
-	if (!create_stub(sechdrs, &stubs[i], addr, me))
+	if (!create_stub(elf_info, &stubs[i], addr, obj_name))
 		return 0;
 
 	return (unsigned long)&stubs[i];
@@ -465,24 +414,7 @@ static bool is_early_mcount_callsite(u32 *instruction)
 	return false;
 }
 
-/*
- * In case of _mcount calls, do not save the current callee's TOC (in r2) into
- * the original caller's stack frame. If we did we would clobber the saved TOC
- * value of the original caller.
- */
-static void squash_toc_save_inst(const char *name, unsigned long addr)
-{
-	struct ppc64_stub_entry *stub = (struct ppc64_stub_entry *)addr;
-
-	/* Only for calls to _mcount */
-	if (strcmp("_mcount", name) != 0)
-		return;
-
-	stub->jump[2] = PPC_INST_NOP;
-}
 #else
-static void squash_toc_save_inst(const char *name, unsigned long addr) { }
-
 /* without -mprofile-kernel, mcount calls are never early */
 static bool is_early_mcount_callsite(u32 *instruction)
 {
@@ -492,13 +424,13 @@ static bool is_early_mcount_callsite(u32 *instruction)
 
 /* We expect a noop next: if it is, replace it with instruction to
    restore r2. */
-static int restore_r2(u32 *instruction, struct module *me)
+int restore_r2(u32 *instruction, const char *obj_name)
 {
 	if (*instruction != PPC_INST_NOP) {
 		if (is_early_mcount_callsite(instruction - 1))
 			return 1;
 		pr_err("%s: Expect noop after relocate, got %08x\n",
-		       me->name, *instruction);
+		       obj_name, *instruction);
 		return 0;
 	}
 	/* ld r2,R2_STACK_OFFSET(r1) */
@@ -512,11 +444,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 		       unsigned int relsec,
 		       struct module *me)
 {
-	unsigned int i;
-	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
 	Elf64_Sym *sym;
-	unsigned long *location;
-	unsigned long value;
 
 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
 	       sechdrs[relsec].sh_info);
@@ -527,191 +455,12 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 		/* It's theoretically possible that a module doesn't want a
 		 * .TOC. so don't fail it just for that. */
 		if (sym)
-			sym->st_value = my_r2(sechdrs, me);
+			sym->st_value = my_r2(&me->arch.elf_info);
 		me->arch.toc_fixed = true;
 	}
 
-	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
-		/* This is where to make the change */
-		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
-			+ rela[i].r_offset;
-		/* This is the symbol it is referring to */
-		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
-			+ ELF64_R_SYM(rela[i].r_info);
-
-		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
-		       location, (long)ELF64_R_TYPE(rela[i].r_info),
-		       strtab + sym->st_name, (unsigned long)sym->st_value,
-		       (long)rela[i].r_addend);
-
-		/* `Everything is relative'. */
-		value = sym->st_value + rela[i].r_addend;
-
-		switch (ELF64_R_TYPE(rela[i].r_info)) {
-		case R_PPC64_ADDR32:
-			/* Simply set it */
-			*(u32 *)location = value;
-			break;
-
-		case R_PPC64_ADDR64:
-			/* Simply set it */
-			*(unsigned long *)location = value;
-			break;
-
-		case R_PPC64_TOC:
-			*(unsigned long *)location = my_r2(sechdrs, me);
-			break;
-
-		case R_PPC64_TOC16:
-			/* Subtract TOC pointer */
-			value -= my_r2(sechdrs, me);
-			if (value + 0x8000 > 0xffff) {
-				pr_err("%s: bad TOC16 relocation (0x%lx)\n",
-				       me->name, value);
-				return -ENOEXEC;
-			}
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xffff)
-				| (value & 0xffff);
-			break;
-
-		case R_PPC64_TOC16_LO:
-			/* Subtract TOC pointer */
-			value -= my_r2(sechdrs, me);
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xffff)
-				| (value & 0xffff);
-			break;
-
-		case R_PPC64_TOC16_DS:
-			/* Subtract TOC pointer */
-			value -= my_r2(sechdrs, me);
-			if ((value & 3) != 0 || value + 0x8000 > 0xffff) {
-				pr_err("%s: bad TOC16_DS relocation (0x%lx)\n",
-				       me->name, value);
-				return -ENOEXEC;
-			}
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xfffc)
-				| (value & 0xfffc);
-			break;
-
-		case R_PPC64_TOC16_LO_DS:
-			/* Subtract TOC pointer */
-			value -= my_r2(sechdrs, me);
-			if ((value & 3) != 0) {
-				pr_err("%s: bad TOC16_LO_DS relocation (0x%lx)\n",
-				       me->name, value);
-				return -ENOEXEC;
-			}
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xfffc)
-				| (value & 0xfffc);
-			break;
-
-		case R_PPC64_TOC16_HA:
-			/* Subtract TOC pointer */
-			value -= my_r2(sechdrs, me);
-			value = ((value + 0x8000) >> 16);
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xffff)
-				| (value & 0xffff);
-			break;
-
-		case R_PPC_REL24:
-			/* FIXME: Handle weak symbols here --RR */
-			if (sym->st_shndx == SHN_UNDEF) {
-				/* External: go via stub */
-				value = stub_for_addr(sechdrs, value, me);
-				if (!value)
-					return -ENOENT;
-				if (!restore_r2((u32 *)location + 1, me))
-					return -ENOEXEC;
-
-				squash_toc_save_inst(strtab + sym->st_name, value);
-			} else
-				value += local_entry_offset(sym);
-
-			/* Convert value to relative */
-			value -= (unsigned long)location;
-			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
-				pr_err("%s: REL24 %li out of range!\n",
-				       me->name, (long int)value);
-				return -ENOEXEC;
-			}
-
-			/* Only replace bits 2 through 26 */
-			*(uint32_t *)location
-				= (*(uint32_t *)location & ~0x03fffffc)
-				| (value & 0x03fffffc);
-			break;
-
-		case R_PPC64_REL64:
-			/* 64 bits relative (used by features fixups) */
-			*location = value - (unsigned long)location;
-			break;
-
-		case R_PPC64_TOCSAVE:
-			/*
-			 * Marker reloc indicates we don't have to save r2.
-			 * That would only save us one instruction, so ignore
-			 * it.
-			 */
-			break;
-
-		case R_PPC64_ENTRY:
-			/*
-			 * Optimize ELFv2 large code model entry point if
-			 * the TOC is within 2GB range of current location.
-			 */
-			value = my_r2(sechdrs, me) - (unsigned long)location;
-			if (value + 0x80008000 > 0xffffffff)
-				break;
-			/*
-			 * Check for the large code model prolog sequence:
-		         *	ld r2, ...(r12)
-			 *	add r2, r2, r12
-			 */
-			if ((((uint32_t *)location)[0] & ~0xfffc)
-			    != 0xe84c0000)
-				break;
-			if (((uint32_t *)location)[1] != 0x7c426214)
-				break;
-			/*
-			 * If found, replace it with:
-			 *	addis r2, r12, (.TOC.-func)@ha
-			 *	addi r2, r12, (.TOC.-func)@l
-			 */
-			((uint32_t *)location)[0] = 0x3c4c0000 + PPC_HA(value);
-			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
-			break;
-
-		case R_PPC64_REL16_HA:
-			/* Subtract location pointer */
-			value -= (unsigned long)location;
-			value = ((value + 0x8000) >> 16);
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xffff)
-				| (value & 0xffff);
-			break;
-
-		case R_PPC64_REL16_LO:
-			/* Subtract location pointer */
-			value -= (unsigned long)location;
-			*((uint16_t *) location)
-				= (*((uint16_t *) location) & ~0xffff)
-				| (value & 0xffff);
-			break;
-
-		default:
-			pr_err("%s: Unknown ADD relocation: %lu\n",
-			       me->name,
-			       (unsigned long)ELF64_R_TYPE(rela[i].r_info));
-			return -ENOEXEC;
-		}
-	}
-
-	return 0;
+	return elf64_apply_relocate_add(&me->arch.elf_info, strtab, symindex,
+					relsec, me->name);
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
@@ -745,10 +494,10 @@ static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module
 	};
 	long reladdr;
 
-	num_stubs = sechdrs[me->arch.stubs_section].sh_size / sizeof(*entry);
+	num_stubs = sechdrs[me->arch.elf_info.stubs_section].sh_size / sizeof(*entry);
 
 	/* Find the next available stub entry */
-	entry = (void *)sechdrs[me->arch.stubs_section].sh_addr;
+	entry = (void *)sechdrs[me->arch.elf_info.stubs_section].sh_addr;
 	for (i = 0; i < num_stubs && stub_func_addr(entry->funcdata); i++, entry++);
 
 	if (i >= num_stubs) {
@@ -777,13 +526,14 @@ static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module
 #else
 static unsigned long create_ftrace_stub(const Elf64_Shdr *sechdrs, struct module *me)
 {
-	return stub_for_addr(sechdrs, (unsigned long)ftrace_caller, me);
+	return stub_for_addr(&me->arch.elf_info, (unsigned long)ftrace_caller,
+			     me->name);
 }
 #endif
 
 int module_finalize_ftrace(struct module *mod, const Elf_Shdr *sechdrs)
 {
-	mod->arch.toc = my_r2(sechdrs, mod);
+	mod->arch.toc = my_r2(&mod->arch.elf_info);
 	mod->arch.tramp = create_ftrace_stub(sechdrs, mod);
 
 	if (!mod->arch.tramp)
-- 
1.9.1

[PATCH v3 5/9] powerpc: Generalize elf64_apply_relocate_add.

[Thiago Jung Bauermann]

When apply_relocate_add is called, modules are already loaded at their
final location in memory so Elf64_Shdr.sh_addr can be used for accessing
the section contents as well as the base address for relocations.

This is not the case for kexec's purgatory, because it will only be
copied to its final location right before being executed. Therefore,
it needs to be relocated while it is still in a temporary buffer. In
this case, Elf64_Shdr.sh_addr can't be used to access the sections'
contents.

This patch allows elf64_apply_relocate_add to be used when the ELF
binary is not yet at its final location by adding an addr_base argument
to specify the address at which the section will be loaded, and rela,
loc_base and syms_base to point to the sections' contents.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Torsten Duwe <duwe@suse.de>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/include/asm/elf_util.h |  6 ++--
 arch/powerpc/kernel/elf_util_64.c   | 63 +++++++++++++++++++++++++------------
 arch/powerpc/kernel/module_64.c     | 17 ++++++++--
 3 files changed, 61 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/include/asm/elf_util.h b/arch/powerpc/include/asm/elf_util.h
index 37372559fe62..a012ba03282d 100644
--- a/arch/powerpc/include/asm/elf_util.h
+++ b/arch/powerpc/include/asm/elf_util.h
@@ -64,7 +64,9 @@ static inline unsigned long my_r2(const struct elf_info *elf_info)
 }
 
 int elf64_apply_relocate_add(const struct elf_info *elf_info,
-			     const char *strtab, unsigned int symindex,
-			     unsigned int relsec, const char *obj_name);
+			     const char *strtab, const Elf64_Rela *rela,
+			     unsigned int num_rela, void *syms_base,
+			     void *loc_base, Elf64_Addr addr_base,
+			     const char *obj_name);
 
 #endif /* _ASM_POWERPC_ELF_UTIL_H */
diff --git a/arch/powerpc/kernel/elf_util_64.c b/arch/powerpc/kernel/elf_util_64.c
index decad2c34f38..8e5d400ac9f2 100644
--- a/arch/powerpc/kernel/elf_util_64.c
+++ b/arch/powerpc/kernel/elf_util_64.c
@@ -69,33 +69,56 @@ static void squash_toc_save_inst(const char *name, unsigned long addr) { }
  * elf64_apply_relocate_add - apply 64 bit RELA relocations
  * @elf_info:		Support information for the ELF binary being relocated.
  * @strtab:		String table for the associated symbol table.
- * @symindex:		Section header index for the associated symbol table.
- * @relsec:		Section header index for the relocations to apply.
+ * @rela:		Contents of the section with the relocations to apply.
+ * @num_rela:		Number of relocation entries in the section.
+ * @syms_base:		Contents of the associated symbol table.
+ * @loc_base:		Contents of the section to which relocations apply.
+ * @addr_base:		The address where the section will be loaded in memory.
  * @obj_name:		The name of the ELF binary, for information messages.
+ *
+ * Applies RELA relocations to an ELF file already at its final location
+ * in memory (in which case loc_base == addr_base), or still in a temporary
+ * buffer.
  */
 int elf64_apply_relocate_add(const struct elf_info *elf_info,
-			     const char *strtab, unsigned int symindex,
-			     unsigned int relsec, const char *obj_name)
+			     const char *strtab, const Elf64_Rela *rela,
+			     unsigned int num_rela, void *syms_base,
+			     void *loc_base, Elf64_Addr addr_base,
+			     const char *obj_name)
 {
 	unsigned int i;
-	Elf64_Shdr *sechdrs = elf_info->sechdrs;
-	Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr;
-	Elf64_Sym *sym;
 	unsigned long *location;
+	unsigned long address;
 	unsigned long value;
+	const char *name;
+	Elf64_Sym *sym;
+
+	for (i = 0; i < num_rela; i++) {
+		/*
+		 * rels[i].r_offset contains the byte offset from the beginning
+		 * of section to the storage unit affected.
+		 *
+		 * This is the location to update in the temporary buffer where
+		 * the section is currently loaded. The section will finally
+		 * be loaded to a different address later, pointed to by
+		 * addr_base.
+		 */
+		location = loc_base + rela[i].r_offset;
+
+		/* Final address of the location. */
+		address = addr_base + rela[i].r_offset;
 
+		/* This is the symbol the relocation is referring to. */
+		sym = (Elf64_Sym *) syms_base + ELF64_R_SYM(rela[i].r_info);
 
-	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
-		/* This is where to make the change */
-		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
-			+ rela[i].r_offset;
-		/* This is the symbol it is referring to */
-		sym = (Elf64_Sym *)sechdrs[symindex].sh_addr
-			+ ELF64_R_SYM(rela[i].r_info);
+		if (sym->st_name)
+			name = strtab + sym->st_name;
+		else
+			name = "<unnamed symbol>";
 
 		pr_debug("RELOC at %p: %li-type as %s (0x%lx) + %li\n",
 		       location, (long)ELF64_R_TYPE(rela[i].r_info),
-		       strtab + sym->st_name, (unsigned long)sym->st_value,
+		       name, (unsigned long)sym->st_value,
 		       (long)rela[i].r_addend);
 
 		/* `Everything is relative'. */
@@ -187,7 +210,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 				value += local_entry_offset(sym);
 
 			/* Convert value to relative */
-			value -= (unsigned long)location;
+			value -= address;
 			if (value + 0x2000000 > 0x3ffffff || (value & 3) != 0){
 				pr_err("%s: REL24 %li out of range!\n",
 				       obj_name, (long int)value);
@@ -202,7 +225,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 
 		case R_PPC64_REL64:
 			/* 64 bits relative (used by features fixups) */
-			*location = value - (unsigned long)location;
+			*location = value - address;
 			break;
 
 		case R_PPC64_TOCSAVE:
@@ -218,7 +241,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			 * Optimize ELFv2 large code model entry point if
 			 * the TOC is within 2GB range of current location.
 			 */
-			value = my_r2(elf_info) - (unsigned long)location;
+			value = my_r2(elf_info) - address;
 			if (value + 0x80008000 > 0xffffffff)
 				break;
 			/*
@@ -242,7 +265,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 
 		case R_PPC64_REL16_HA:
 			/* Subtract location pointer */
-			value -= (unsigned long)location;
+			value -= address;
 			value = ((value + 0x8000) >> 16);
 			*((uint16_t *) location)
 				= (*((uint16_t *) location) & ~0xffff)
@@ -251,7 +274,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 
 		case R_PPC64_REL16_LO:
 			/* Subtract location pointer */
-			value -= (unsigned long)location;
+			value -= address;
 			*((uint16_t *) location)
 				= (*((uint16_t *) location) & ~0xffff)
 				| (value & 0xffff);
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index f2b25b4f9066..7f3b17bcac05 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -438,16 +438,26 @@ int restore_r2(u32 *instruction, const char *obj_name)
 	return 1;
 }
 
+/*
+ * When this function is called, the module is already at its final location in
+ * memory, so Elf64_Shdr.sh_addr can be used for accessing the section
+ * contents as well as the base address for relocations.
+ */
 int apply_relocate_add(Elf64_Shdr *sechdrs,
 		       const char *strtab,
 		       unsigned int symindex,
 		       unsigned int relsec,
 		       struct module *me)
 {
+	Elf64_Shdr *rel_section = &sechdrs[relsec];
+	void *syms_base = (void *) sechdrs[symindex].sh_addr;
+	Elf64_Addr addr_base = sechdrs[rel_section->sh_info].sh_addr;
+	const Elf64_Rela *rela = (const Elf64_Rela *) rel_section->sh_addr;
+	unsigned int num_rela = rel_section->sh_size / sizeof(Elf64_Rela);
 	Elf64_Sym *sym;
 
 	pr_debug("Applying ADD relocate section %u to %u\n", relsec,
-	       sechdrs[relsec].sh_info);
+		 rel_section->sh_info);
 
 	/* First time we're called, we can fix up .TOC. */
 	if (!me->arch.toc_fixed) {
@@ -459,8 +469,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 		me->arch.toc_fixed = true;
 	}
 
-	return elf64_apply_relocate_add(&me->arch.elf_info, strtab, symindex,
-					relsec, me->name);
+	return elf64_apply_relocate_add(&me->arch.elf_info, strtab, rela,
+					num_rela, syms_base, (void *) addr_base,
+					addr_base, me->name);
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-- 
1.9.1

[PATCH v3 6/9] powerpc: Add functions to read ELF files of any endianness.

[Thiago Jung Bauermann]

A little endian kernel might need to kexec a big endian kernel (the
opposite is less likely but could happen as well), so we can't just cast
the buffer with the binary to ELF structs and use them as is done
elsewhere.

This patch adds functions which do byte-swapping as necessary when
populating the ELF structs. These functions will be used in the next
patch in the series.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/include/asm/elf_util.h |  19 ++
 arch/powerpc/kernel/Makefile        |   2 +-
 arch/powerpc/kernel/elf_util.c      | 476 ++++++++++++++++++++++++++++++++++++
 3 files changed, 496 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/elf_util.h b/arch/powerpc/include/asm/elf_util.h
index a012ba03282d..47d15515ba33 100644
--- a/arch/powerpc/include/asm/elf_util.h
+++ b/arch/powerpc/include/asm/elf_util.h
@@ -20,6 +20,14 @@
 #include <linux/elf.h>
 
 struct elf_info {
+	/*
+	 * Where the ELF binary contents are kept.
+	 * Memory managed by the user of the struct.
+	 */
+	const char *buffer;
+
+	const struct elfhdr *ehdr;
+	const struct elf_phdr *proghdrs;
 	struct elf_shdr *sechdrs;
 
 	/* Index of stubs section. */
@@ -63,6 +71,17 @@ static inline unsigned long my_r2(const struct elf_info *elf_info)
 	return elf_info->sechdrs[elf_info->toc_section].sh_addr + 0x8000;
 }
 
+static inline bool elf_is_elf_file(const struct elfhdr *ehdr)
+{
+	return memcmp(ehdr->e_ident, ELFMAG, SELFMAG) == 0;
+}
+
+int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
+			 struct elf_info *elf_info);
+void elf_init_elf_info(const struct elfhdr *ehdr, struct elf_shdr *sechdrs,
+		       struct elf_info *elf_info);
+void elf_free_info(struct elf_info *elf_info);
+
 int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			     const char *strtab, const Elf64_Rela *rela,
 			     unsigned int num_rela, void *syms_base,
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index e99f626acc85..8a53fccaa053 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -125,7 +125,7 @@ obj-y				+= iomap.o
 endif
 
 ifeq ($(CONFIG_MODULES)$(CONFIG_WORD_SIZE),y64)
-obj-y				+= elf_util_64.o
+obj-y				+= elf_util.o elf_util_64.o
 endif
 
 obj64-$(CONFIG_PPC_TRANSACTIONAL_MEM)	+= tm.o
diff --git a/arch/powerpc/kernel/elf_util.c b/arch/powerpc/kernel/elf_util.c
new file mode 100644
index 000000000000..1df4a116ad90
--- /dev/null
+++ b/arch/powerpc/kernel/elf_util.c
@@ -0,0 +1,476 @@
+/*
+ * Utility functions to work with ELF files.
+ *
+ * Copyright (C) 2016, IBM Corporation
+ *
+ * Based on kexec-tools' kexec-elf.c. Heavily modified for the
+ * kernel by Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/slab.h>
+#include <asm/elf_util.h>
+#include <asm-generic/module.h>
+
+#if ELF_CLASS == ELFCLASS32
+#define elf_addr_to_cpu	elf32_to_cpu
+
+#ifndef Elf_Rel
+#define Elf_Rel		Elf32_Rel
+#endif /* Elf_Rel */
+#else /* ELF_CLASS == ELFCLASS32 */
+#define elf_addr_to_cpu	elf64_to_cpu
+
+#ifndef Elf_Rel
+#define Elf_Rel		Elf64_Rel
+#endif /* Elf_Rel */
+
+static uint64_t elf64_to_cpu(const struct elfhdr *ehdr, uint64_t value)
+{
+	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+		value = le64_to_cpu(value);
+	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+		value = be64_to_cpu(value);
+
+	return value;
+}
+#endif /* ELF_CLASS == ELFCLASS32 */
+
+static uint16_t elf16_to_cpu(const struct elfhdr *ehdr, uint16_t value)
+{
+	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+		value = le16_to_cpu(value);
+	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+		value = be16_to_cpu(value);
+
+	return value;
+}
+
+static uint32_t elf32_to_cpu(const struct elfhdr *ehdr, uint32_t value)
+{
+	if (ehdr->e_ident[EI_DATA] == ELFDATA2LSB)
+		value = le32_to_cpu(value);
+	else if (ehdr->e_ident[EI_DATA] == ELFDATA2MSB)
+		value = be32_to_cpu(value);
+
+	return value;
+}
+
+/**
+ * elf_is_ehdr_sane - check that it is safe to use the ELF header
+ * @buf_len:	size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_ehdr_sane(const struct elfhdr *ehdr, size_t buf_len)
+{
+	if (ehdr->e_phnum > 0 && ehdr->e_phentsize != sizeof(struct elf_phdr)) {
+		pr_debug("Bad program header size.\n");
+		return false;
+	} else if (ehdr->e_shnum > 0 &&
+		   ehdr->e_shentsize != sizeof(struct elf_shdr)) {
+		pr_debug("Bad section header size.\n");
+		return false;
+	} else if (ehdr->e_ident[EI_VERSION] != EV_CURRENT ||
+		   ehdr->e_version != EV_CURRENT) {
+		pr_debug("Unknown ELF version.\n");
+		return false;
+	}
+
+	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
+		size_t phdr_size;
+
+		/*
+		 * e_phnum is at most 65535 so calculating the size of the
+		 * program header cannot overflow.
+		 */
+		phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
+
+		/* Sanity check the program header table location. */
+		if (ehdr->e_phoff + phdr_size < ehdr->e_phoff) {
+			pr_debug("Program headers at invalid location.\n");
+			return false;
+		} else if (ehdr->e_phoff + phdr_size > buf_len) {
+			pr_debug("Program headers truncated.\n");
+			return false;
+		}
+	}
+
+	if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
+		size_t shdr_size;
+
+		/*
+		 * e_shnum is at most 65536 so calculating
+		 * the size of the section header cannot overflow.
+		 */
+		shdr_size = sizeof(struct elf_shdr) * ehdr->e_shnum;
+
+		/* Sanity check the section header table location. */
+		if (ehdr->e_shoff + shdr_size < ehdr->e_shoff) {
+			pr_debug("Section headers at invalid location.\n");
+			return false;
+		} else if (ehdr->e_shoff + shdr_size > buf_len) {
+			pr_debug("Section headers truncated.\n");
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
+{
+	struct elfhdr *buf_ehdr;
+
+	if (len < sizeof(*buf_ehdr)) {
+		pr_debug("Buffer is too small to hold ELF header.\n");
+		return -ENOEXEC;
+	}
+
+	memset(ehdr, 0, sizeof(*ehdr));
+	memcpy(ehdr->e_ident, buf, sizeof(ehdr->e_ident));
+	if (!elf_is_elf_file(ehdr)) {
+		pr_debug("No ELF header magic.\n");
+		return -ENOEXEC;
+	}
+
+	if (ehdr->e_ident[EI_CLASS] != ELF_CLASS) {
+		pr_debug("Not a supported ELF class.\n");
+		return -1;
+	} else  if (ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
+		ehdr->e_ident[EI_DATA] != ELFDATA2MSB) {
+		pr_debug("Not a supported ELF data format.\n");
+		return -ENOEXEC;
+	}
+
+	buf_ehdr = (struct elfhdr *) buf;
+	if (elf16_to_cpu(ehdr, buf_ehdr->e_ehsize) != sizeof(*buf_ehdr)) {
+		pr_debug("Bad ELF header size.\n");
+		return -ENOEXEC;
+	}
+
+	ehdr->e_type      = elf16_to_cpu(ehdr, buf_ehdr->e_type);
+	ehdr->e_machine   = elf16_to_cpu(ehdr, buf_ehdr->e_machine);
+	ehdr->e_version   = elf32_to_cpu(ehdr, buf_ehdr->e_version);
+	ehdr->e_entry     = elf_addr_to_cpu(ehdr, buf_ehdr->e_entry);
+	ehdr->e_phoff     = elf_addr_to_cpu(ehdr, buf_ehdr->e_phoff);
+	ehdr->e_shoff     = elf_addr_to_cpu(ehdr, buf_ehdr->e_shoff);
+	ehdr->e_flags     = elf32_to_cpu(ehdr, buf_ehdr->e_flags);
+	ehdr->e_phentsize = elf16_to_cpu(ehdr, buf_ehdr->e_phentsize);
+	ehdr->e_phnum     = elf16_to_cpu(ehdr, buf_ehdr->e_phnum);
+	ehdr->e_shentsize = elf16_to_cpu(ehdr, buf_ehdr->e_shentsize);
+	ehdr->e_shnum     = elf16_to_cpu(ehdr, buf_ehdr->e_shnum);
+	ehdr->e_shstrndx  = elf16_to_cpu(ehdr, buf_ehdr->e_shstrndx);
+
+	return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_is_phdr_sane - check that it is safe to use the program header
+ * @buf_len:	size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_phdr_sane(const struct elf_phdr *phdr, size_t buf_len)
+{
+
+	if (phdr->p_offset + phdr->p_filesz < phdr->p_offset) {
+		pr_debug("ELF segment location wraps around.\n");
+		return false;
+	} else if (phdr->p_offset + phdr->p_filesz > buf_len) {
+		pr_debug("ELF segment not in file.\n");
+		return false;
+	} else if (phdr->p_paddr + phdr->p_memsz < phdr->p_paddr) {
+		pr_debug("ELF segment address wraps around.\n");
+		return false;
+	}
+
+	return true;
+}
+
+static int elf_read_phdr(const char *buf, size_t len, struct elf_info *elf_info,
+			 int idx)
+{
+	/* Override the const in proghdrs, we are the ones doing the loading. */
+	struct elf_phdr *phdr = (struct elf_phdr *) &elf_info->proghdrs[idx];
+	const char *pbuf;
+	struct elf_phdr *buf_phdr;
+
+	pbuf = buf + elf_info->ehdr->e_phoff + (idx * sizeof(*buf_phdr));
+	buf_phdr = (struct elf_phdr *) pbuf;
+
+	phdr->p_type   = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_type);
+	phdr->p_offset = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_offset);
+	phdr->p_paddr  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_paddr);
+	phdr->p_vaddr  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_vaddr);
+	phdr->p_flags  = elf32_to_cpu(elf_info->ehdr, buf_phdr->p_flags);
+
+	/*
+	 * The following fields have a type equivalent to Elf_Addr
+	 * both in 32 bit and 64 bit ELF.
+	 */
+	phdr->p_filesz = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_filesz);
+	phdr->p_memsz  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_memsz);
+	phdr->p_align  = elf_addr_to_cpu(elf_info->ehdr, buf_phdr->p_align);
+
+	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_read_phdrs - read the program headers from the buffer
+ *
+ * This function assumes that the program header table was checked for sanity.
+ * Use elf_is_ehdr_sane() if it wasn't.
+ */
+static int elf_read_phdrs(const char *buf, size_t len,
+			  struct elf_info *elf_info)
+{
+	size_t phdr_size, i;
+	const struct elfhdr *ehdr = elf_info->ehdr;
+
+	/*
+	 * e_phnum is at most 65535 so calculating the size of the
+	 * program header cannot overflow.
+	 */
+	phdr_size = sizeof(struct elf_phdr) * ehdr->e_phnum;
+
+	elf_info->proghdrs = kzalloc(phdr_size, GFP_KERNEL);
+	if (!elf_info->proghdrs)
+		return -ENOMEM;
+
+	for (i = 0; i < ehdr->e_phnum; i++) {
+		int ret;
+
+		ret = elf_read_phdr(buf, len, elf_info, i);
+		if (ret) {
+			kfree(elf_info->proghdrs);
+			elf_info->proghdrs = NULL;
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * elf_is_shdr_sane - check that it is safe to use the section header
+ * @buf_len:	size of the buffer in which the ELF file is loaded.
+ */
+static bool elf_is_shdr_sane(const struct elf_shdr *shdr, size_t buf_len)
+{
+	bool size_ok;
+
+	/* SHT_NULL headers have undefined values, so we can't check them. */
+	if (shdr->sh_type == SHT_NULL)
+		return true;
+
+	/* Now verify sh_entsize */
+	switch (shdr->sh_type) {
+	case SHT_SYMTAB:
+		size_ok = shdr->sh_entsize == sizeof(Elf_Sym);
+		break;
+	case SHT_RELA:
+		size_ok = shdr->sh_entsize == sizeof(Elf_Rela);
+		break;
+	case SHT_DYNAMIC:
+		size_ok = shdr->sh_entsize == sizeof(Elf_Dyn);
+		break;
+	case SHT_REL:
+		size_ok = shdr->sh_entsize == sizeof(Elf_Rel);
+		break;
+	case SHT_NOTE:
+	case SHT_PROGBITS:
+	case SHT_HASH:
+	case SHT_NOBITS:
+	default:
+		/*
+		 * This is a section whose entsize requirements
+		 * I don't care about.  If I don't know about
+		 * the section I can't care about it's entsize
+		 * requirements.
+		 */
+		size_ok = true;
+		break;
+	}
+
+	if (!size_ok) {
+		pr_debug("ELF section with wrong entry size.\n");
+		return false;
+	} else if (shdr->sh_addr + shdr->sh_size < shdr->sh_addr) {
+		pr_debug("ELF section address wraps around.\n");
+		return false;
+	}
+
+	if (shdr->sh_type != SHT_NOBITS) {
+		if (shdr->sh_offset + shdr->sh_size < shdr->sh_offset) {
+			pr_debug("ELF section location wraps around.\n");
+			return false;
+		} else if (shdr->sh_offset + shdr->sh_size > buf_len) {
+			pr_debug("ELF section not in file.\n");
+			return false;
+		}
+	}
+
+	return true;
+}
+
+static int elf_read_shdr(const char *buf, size_t len, struct elf_info *elf_info,
+			 int idx)
+{
+	struct elf_shdr *shdr = &elf_info->sechdrs[idx];
+	const struct elfhdr *ehdr = elf_info->ehdr;
+	const char *sbuf;
+	struct elf_shdr *buf_shdr;
+
+	sbuf = buf + ehdr->e_shoff + idx * sizeof(*buf_shdr);
+	buf_shdr = (struct elf_shdr *) sbuf;
+
+	shdr->sh_name      = elf32_to_cpu(ehdr, buf_shdr->sh_name);
+	shdr->sh_type      = elf32_to_cpu(ehdr, buf_shdr->sh_type);
+	shdr->sh_addr      = elf_addr_to_cpu(ehdr, buf_shdr->sh_addr);
+	shdr->sh_offset    = elf_addr_to_cpu(ehdr, buf_shdr->sh_offset);
+	shdr->sh_link      = elf32_to_cpu(ehdr, buf_shdr->sh_link);
+	shdr->sh_info      = elf32_to_cpu(ehdr, buf_shdr->sh_info);
+
+	/*
+	 * The following fields have a type equivalent to Elf_Addr
+	 * both in 32 bit and 64 bit ELF.
+	 */
+	shdr->sh_flags     = elf_addr_to_cpu(ehdr, buf_shdr->sh_flags);
+	shdr->sh_size      = elf_addr_to_cpu(ehdr, buf_shdr->sh_size);
+	shdr->sh_addralign = elf_addr_to_cpu(ehdr, buf_shdr->sh_addralign);
+	shdr->sh_entsize   = elf_addr_to_cpu(ehdr, buf_shdr->sh_entsize);
+
+	return elf_is_shdr_sane(shdr, len) ? 0 : -ENOEXEC;
+}
+
+/**
+ * elf_read_shdrs - read the section headers from the buffer
+ *
+ * This function assumes that the section header table was checked for sanity.
+ * Use elf_is_ehdr_sane() if it wasn't.
+ */
+static int elf_read_shdrs(const char *buf, size_t len,
+			  struct elf_info *elf_info)
+{
+	size_t shdr_size, i;
+
+	/*
+	 * e_shnum is at most 65536 so calculating
+	 * the size of the section header cannot overflow.
+	 */
+	shdr_size = sizeof(struct elf_shdr) * elf_info->ehdr->e_shnum;
+
+	elf_info->sechdrs = kzalloc(shdr_size, GFP_KERNEL);
+	if (!elf_info->sechdrs)
+		return -ENOMEM;
+
+	for (i = 0; i < elf_info->ehdr->e_shnum; i++) {
+		int ret;
+
+		ret = elf_read_shdr(buf, len, elf_info, i);
+		if (ret) {
+			kfree(elf_info->sechdrs);
+			elf_info->sechdrs = NULL;
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * elf_read_from_buffer - read ELF file and sets up ELF header and ELF info
+ * @buf:	Buffer to read ELF file from.
+ * @len:	Size of @buf.
+ * @ehdr:	Pointer to existing struct which will be populated.
+ * @elf_info:	Pointer to existing struct which will be populated.
+ *
+ * This function allows reading ELF files with different byte order than
+ * the kernel, byte-swapping the fields as needed.
+ *
+ * Return:
+ * On success returns 0, and the caller should call elf_free_info(elf_info) to
+ * free the memory allocated for the section and program headers.
+ */
+int elf_read_from_buffer(const char *buf, size_t len, struct elfhdr *ehdr,
+			 struct elf_info *elf_info)
+{
+	int ret;
+
+	ret = elf_read_ehdr(buf, len, ehdr);
+	if (ret)
+		return ret;
+
+	elf_info->buffer = buf;
+	elf_info->ehdr = ehdr;
+	if (ehdr->e_phoff > 0 && ehdr->e_phnum > 0) {
+		ret = elf_read_phdrs(buf, len, elf_info);
+		if (ret)
+			return ret;
+	}
+	if (ehdr->e_shoff > 0 && ehdr->e_shnum > 0) {
+		ret = elf_read_shdrs(buf, len, elf_info);
+		if (ret) {
+			kfree(elf_info->proghdrs);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * elf_init_elf_info - initialize elf_info from existing information
+ * @ehdr:	Pointer to already loaded ELF header.
+ * @sechdrs:	Pointer to already loaded section headers contents.
+ * @elf_info:	Pointer to existing struct which will be populated.
+ *
+ * If the ELF binary was not loaded using elf_read_from_buffer, this function
+ * can be used to obtain a struct elf_info for use with other ELF utility
+ * functions.
+ *
+ * The caller is responsible for managing @sechdrs memory, users of this
+ * function don't need to call elf_free_info() if they free this memory
+ * separately.
+ */
+void elf_init_elf_info(const struct elfhdr *ehdr, struct elf_shdr *sechdrs,
+		       struct elf_info *elf_info)
+{
+	int i;
+	const char *shstrtab;
+
+	memset(elf_info, 0, sizeof(*elf_info));
+
+	/* Section header string table. */
+	shstrtab = (const char *) sechdrs[ehdr->e_shstrndx].sh_offset;
+
+	for (i = 0; i < ehdr->e_shnum; i++) {
+		if (sechdrs[i].sh_size == 0)
+			continue;
+
+		if (!strcmp(&shstrtab[sechdrs[i].sh_name], ".stubs"))
+			elf_info->stubs_section = i;
+		else if (!strcmp(&shstrtab[sechdrs[i].sh_name], ".toc"))
+			elf_info->toc_section = i;
+	}
+
+	elf_info->ehdr = ehdr;
+	elf_info->sechdrs = sechdrs;
+}
+
+/**
+ * elf_free_info - free memory allocated by elf_read_from_buffer
+ */
+void elf_free_info(struct elf_info *elf_info)
+{
+	kfree(elf_info->proghdrs);
+	kfree(elf_info->sechdrs);
+	memset(elf_info, 0, sizeof(*elf_info));
+}
-- 
1.9.1

[PATCH v3 7/9] powerpc: Implement kexec_file_load.

[Thiago Jung Bauermann]

Adds the basic machinery needed by kexec_file_load.

Signed-off-by: Josh Sklar <sklar@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/Kconfig                   | 13 +++++++++
 arch/powerpc/include/asm/systbl.h      |  1 +
 arch/powerpc/include/asm/unistd.h      |  2 +-
 arch/powerpc/include/uapi/asm/unistd.h |  1 +
 arch/powerpc/kernel/machine_kexec_64.c | 50 ++++++++++++++++++++++++++++++++++
 5 files changed, 66 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 01f7464d9fea..3ed5770b89e4 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -457,6 +457,19 @@ config KEXEC
 	  interface is strongly in flux, so no good recommendation can be
 	  made.
 
+config KEXEC_FILE
+	bool "kexec file based system call"
+	select KEXEC_CORE
+	select BUILD_BIN2C
+	depends on PPC64
+	depends on CRYPTO=y
+	depends on CRYPTO_SHA256=y
+	help
+	  This is a new version of the kexec system call. This call is
+	  file based and takes in file descriptors as system call arguments
+	  for kernel and initramfs as opposed to a list of segments as is the
+	  case for the older kexec call.
+
 config CRASH_DUMP
 	bool "Build a kdump crash kernel"
 	depends on PPC64 || 6xx || FSL_BOOKE || (44x && !SMP)
diff --git a/arch/powerpc/include/asm/systbl.h b/arch/powerpc/include/asm/systbl.h
index 2fc5d4db503c..4b369d83fe9c 100644
--- a/arch/powerpc/include/asm/systbl.h
+++ b/arch/powerpc/include/asm/systbl.h
@@ -386,3 +386,4 @@ SYSCALL(mlock2)
 SYSCALL(copy_file_range)
 COMPAT_SYS_SPU(preadv2)
 COMPAT_SYS_SPU(pwritev2)
+SYSCALL(kexec_file_load)
diff --git a/arch/powerpc/include/asm/unistd.h b/arch/powerpc/include/asm/unistd.h
index cf12c580f6b2..a01e97d3f305 100644
--- a/arch/powerpc/include/asm/unistd.h
+++ b/arch/powerpc/include/asm/unistd.h
@@ -12,7 +12,7 @@
 #include <uapi/asm/unistd.h>
 
 
-#define NR_syscalls		382
+#define NR_syscalls		383
 
 #define __NR__exit __NR_exit
 
diff --git a/arch/powerpc/include/uapi/asm/unistd.h b/arch/powerpc/include/uapi/asm/unistd.h
index e9f5f41aa55a..2f26335a3c42 100644
--- a/arch/powerpc/include/uapi/asm/unistd.h
+++ b/arch/powerpc/include/uapi/asm/unistd.h
@@ -392,5 +392,6 @@
 #define __NR_copy_file_range	379
 #define __NR_preadv2		380
 #define __NR_pwritev2		381
+#define __NR_kexec_file_load	382
 
 #endif /* _UAPI_ASM_POWERPC_UNISTD_H_ */
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 50bf55135ef8..b242f2293a6e 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -31,6 +31,10 @@
 #include <asm/hw_breakpoint.h>
 #include <asm/asm-prototypes.h>
 
+#ifdef CONFIG_KEXEC_FILE
+static struct kexec_file_ops *kexec_file_loaders[] = { };
+#endif
+
 #ifdef CONFIG_PPC_BOOK3E
 int default_machine_kexec_prepare(struct kimage *image)
 {
@@ -427,3 +431,49 @@ static int __init export_htab_values(void)
 }
 late_initcall(export_htab_values);
 #endif /* CONFIG_PPC_STD_MMU_64 */
+
+#ifdef CONFIG_KEXEC_FILE
+int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
+				  unsigned long buf_len)
+{
+	int i, ret = -ENOEXEC;
+	struct kexec_file_ops *fops;
+
+	/* We don't support crash kernels yet. */
+	if (image->type == KEXEC_TYPE_CRASH)
+		return -ENOTSUPP;
+
+	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
+		fops = kexec_file_loaders[i];
+		if (!fops || !fops->probe)
+			continue;
+
+		ret = fops->probe(buf, buf_len);
+		if (!ret) {
+			image->fops = fops;
+			return ret;
+		}
+	}
+
+	return ret;
+}
+
+void *arch_kexec_kernel_image_load(struct kimage *image)
+{
+	if (!image->fops || !image->fops->load)
+		return ERR_PTR(-ENOEXEC);
+
+	return image->fops->load(image, image->kernel_buf,
+				 image->kernel_buf_len, image->initrd_buf,
+				 image->initrd_buf_len, image->cmdline_buf,
+				 image->cmdline_buf_len);
+}
+
+int arch_kimage_file_post_load_cleanup(struct kimage *image)
+{
+	if (!image->fops || !image->fops->cleanup)
+		return 0;
+
+	return image->fops->cleanup(image->image_loader_data);
+}
+#endif /* CONFIG_KEXEC_FILE */
-- 
1.9.1

[PATCH v3 8/9] powerpc: Add support for loading ELF kernels with kexec_file_load.

[Thiago Jung Bauermann]

This uses all the infrastructure built up by the previous patches
in the series to load an ELF vmlinux file and an initrd. It uses the
flattened device tree at initial_boot_params as a base and adjusts memory
reservations and its /chosen node for the next kernel.

elf64_apply_relocate_add was extended to support relative symbols. This
is necessary because before relocation, the module loading mechanism
adjusts Elf64_Sym.st_value to point to the absolute memory address
while the kexec purgatory relocation code does that during relocation.

The patch also adds relocation types used by the purgatory.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/include/asm/elf_util.h     |   1 +
 arch/powerpc/include/asm/kexec_elf_64.h |  10 +
 arch/powerpc/kernel/Makefile            |   5 +-
 arch/powerpc/kernel/elf_util_64.c       |  84 ++++-
 arch/powerpc/kernel/kexec_elf_64.c      | 560 ++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/machine_kexec_64.c  |  86 ++++-
 arch/powerpc/kernel/module_64.c         |   5 +-
 7 files changed, 747 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/elf_util.h b/arch/powerpc/include/asm/elf_util.h
index 47d15515ba33..18703d56eabd 100644
--- a/arch/powerpc/include/asm/elf_util.h
+++ b/arch/powerpc/include/asm/elf_util.h
@@ -86,6 +86,7 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			     const char *strtab, const Elf64_Rela *rela,
 			     unsigned int num_rela, void *syms_base,
 			     void *loc_base, Elf64_Addr addr_base,
+			     bool relative_symbols, bool check_symbols,
 			     const char *obj_name);
 
 #endif /* _ASM_POWERPC_ELF_UTIL_H */
diff --git a/arch/powerpc/include/asm/kexec_elf_64.h b/arch/powerpc/include/asm/kexec_elf_64.h
new file mode 100644
index 000000000000..30da6bc0ccf8
--- /dev/null
+++ b/arch/powerpc/include/asm/kexec_elf_64.h
@@ -0,0 +1,10 @@
+#ifndef __POWERPC_KEXEC_ELF_64_H__
+#define __POWERPC_KEXEC_ELF_64_H__
+
+#ifdef CONFIG_KEXEC_FILE
+
+extern struct kexec_file_ops kexec_elf64_ops;
+
+#endif /* CONFIG_KEXEC_FILE */
+
+#endif /* __POWERPC_KEXEC_ELF_64_H__ */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 8a53fccaa053..b89a2ae1b2a0 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_PCI)		+= pci_$(CONFIG_WORD_SIZE).o $(pci64-y) \
 obj-$(CONFIG_PCI_MSI)		+= msi.o
 obj-$(CONFIG_KEXEC)		+= machine_kexec.o crash.o \
 				   machine_kexec_$(CONFIG_WORD_SIZE).o
+obj-$(CONFIG_KEXEC_FILE)	+= kexec_elf_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_AUDIT)		+= audit.o
 obj64-$(CONFIG_AUDIT)		+= compat_audit.o
 
@@ -124,9 +125,11 @@ ifneq ($(CONFIG_PPC_INDIRECT_PIO),y)
 obj-y				+= iomap.o
 endif
 
-ifeq ($(CONFIG_MODULES)$(CONFIG_WORD_SIZE),y64)
+ifneq ($(CONFIG_MODULES)$(CONFIG_KEXEC_FILE),)
+ifeq ($(CONFIG_WORD_SIZE),64)
 obj-y				+= elf_util.o elf_util_64.o
 endif
+endif
 
 obj64-$(CONFIG_PPC_TRANSACTIONAL_MEM)	+= tm.o
 
diff --git a/arch/powerpc/kernel/elf_util_64.c b/arch/powerpc/kernel/elf_util_64.c
index 8e5d400ac9f2..80f209a42abd 100644
--- a/arch/powerpc/kernel/elf_util_64.c
+++ b/arch/powerpc/kernel/elf_util_64.c
@@ -74,6 +74,8 @@ static void squash_toc_save_inst(const char *name, unsigned long addr) { }
  * @syms_base:		Contents of the associated symbol table.
  * @loc_base:		Contents of the section to which relocations apply.
  * @addr_base:		The address where the section will be loaded in memory.
+ * @relative_symbols:	Are the symbols' st_value members relative?
+ * @check_symbols:	Fail if an unexpected symbol is found?
  * @obj_name:		The name of the ELF binary, for information messages.
  *
  * Applies RELA relocations to an ELF file already at its final location
@@ -84,11 +86,13 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			     const char *strtab, const Elf64_Rela *rela,
 			     unsigned int num_rela, void *syms_base,
 			     void *loc_base, Elf64_Addr addr_base,
+			     bool relative_symbols, bool check_symbols,
 			     const char *obj_name)
 {
 	unsigned int i;
 	unsigned long *location;
 	unsigned long address;
+	unsigned long sec_base;
 	unsigned long value;
 	const char *name;
 	Elf64_Sym *sym;
@@ -121,8 +125,36 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 		       name, (unsigned long)sym->st_value,
 		       (long)rela[i].r_addend);
 
+		if (check_symbols) {
+			/*
+			 * TOC symbols appear as undefined but should be
+			 * resolved as well, so allow them to be processed.
+			 */
+			if (sym->st_shndx == SHN_UNDEF &&
+					strcmp(name, ".TOC.") != 0) {
+				pr_err("Undefined symbol: %s\n", name);
+				return -ENOEXEC;
+			} else if (sym->st_shndx == SHN_COMMON) {
+				pr_err("Symbol '%s' in common section.\n", name);
+				return -ENOEXEC;
+			}
+		}
+
+		if (relative_symbols && sym->st_shndx != SHN_ABS) {
+			if (sym->st_shndx >= elf_info->ehdr->e_shnum) {
+				pr_err("Invalid section %d for symbol %s\n",
+				       sym->st_shndx, name);
+				return -ENOEXEC;
+			} else {
+				struct elf_shdr *sechdrs = elf_info->sechdrs;
+
+				sec_base = sechdrs[sym->st_shndx].sh_addr;
+			}
+		} else
+			sec_base = 0;
+
 		/* `Everything is relative'. */
-		value = sym->st_value + rela[i].r_addend;
+		value = sym->st_value + sec_base + rela[i].r_addend;
 
 		switch (ELF64_R_TYPE(rela[i].r_info)) {
 		case R_PPC64_ADDR32:
@@ -135,6 +167,10 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			*(unsigned long *)location = value;
 			break;
 
+		case R_PPC64_REL32:
+			*(uint32_t *)location = value - (uint32_t)(uint64_t)location;
+			break;
+
 		case R_PPC64_TOC:
 			*(unsigned long *)location = my_r2(elf_info);
 			break;
@@ -186,6 +222,14 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 				| (value & 0xfffc);
 			break;
 
+		case R_PPC64_TOC16_HI:
+			/* Subtract TOC pointer */
+			value -= my_r2(elf_info);
+			value = value >> 16;
+			*((uint16_t *) location)
+				= (*((uint16_t *) location) & ~0xffff)
+				| (value & 0xffff);
+
 		case R_PPC64_TOC16_HA:
 			/* Subtract TOC pointer */
 			value -= my_r2(elf_info);
@@ -195,6 +239,21 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 				| (value & 0xffff);
 			break;
 
+		case R_PPC64_REL14:
+			/* Convert value to relative */
+			value -= address;
+			if (value + 0x8000 > 0xffff || (value & 3) != 0) {
+				pr_err("%s: REL14 %li out of range!\n", obj_name,
+				       (long int)value);
+				return -ENOEXEC;
+			}
+
+			/* Only replace bits 2 through 16 */
+			*(uint32_t *)location
+				= (*(uint32_t *)location & ~0xfffc)
+				| (value & 0xfffc);
+			break;
+
 		case R_PPC_REL24:
 			/* FIXME: Handle weak symbols here --RR */
 			if (sym->st_shndx == SHN_UNDEF) {
@@ -263,6 +322,29 @@ int elf64_apply_relocate_add(const struct elf_info *elf_info,
 			((uint32_t *)location)[1] = 0x38420000 + PPC_LO(value);
 			break;
 
+		case R_PPC64_ADDR16_LO:
+			*(uint16_t *)location = value & 0xffff;
+			break;
+
+		case R_PPC64_ADDR16_HI:
+			*(uint16_t *)location = (value >> 16) & 0xffff;
+			break;
+
+		case R_PPC64_ADDR16_HA:
+			*(uint16_t *)location = (((value + 0x8000) >> 16) &
+							0xffff);
+			break;
+
+		case R_PPC64_ADDR16_HIGHER:
+			*(uint16_t *)location = (((uint64_t)value >> 32) &
+							0xffff);
+			break;
+
+		case R_PPC64_ADDR16_HIGHEST:
+			*(uint16_t *)location = (((uint64_t)value >> 48) &
+							0xffff);
+			break;
+
 		case R_PPC64_REL16_HA:
 			/* Subtract location pointer */
 			value -= address;
diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
new file mode 100644
index 000000000000..f99bc9617b19
--- /dev/null
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -0,0 +1,560 @@
+/*
+ * Load ELF vmlinux file for the kexec_file_load syscall.
+ *
+ * Copyright (C) 2004  Adam Litke (agl@us.ibm.com)
+ * Copyright (C) 2004  IBM Corp.
+ * Copyright (C) 2005  R Sharada (sharada@in.ibm.com)
+ * Copyright (C) 2006  Mohan Kumar M (mohan@in.ibm.com)
+ * Copyright (C) 2016  IBM Corporation
+ *
+ * Based on kexec-tools' kexec-elf-exec.c and kexec-elf-ppc64.c.
+ * Heavily modified for the kernel by
+ * Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#define pr_fmt(fmt)	"kexec_elf: " fmt
+
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/kexec.h>
+#include <linux/elf.h>
+#include <linux/kexec.h>
+#include <linux/of_fdt.h>
+#include <linux/libfdt.h>
+#include <linux/memblock.h>
+#include <asm/elf_util.h>
+
+extern size_t kexec_purgatory_size;
+
+#define PURGATORY_STACK_SIZE	(16 * 1024)
+#define SLAVE_CODE_SIZE		256
+
+/**
+ * build_elf_exec_info - read ELF executable and check that we can use it
+ */
+static int build_elf_exec_info(const char *buf, size_t len, struct elfhdr *ehdr,
+			       struct elf_info *elf_info)
+{
+	int i;
+	int ret;
+
+	ret = elf_read_from_buffer(buf, len, ehdr, elf_info);
+	if (ret)
+		return ret;
+
+	if (ehdr->e_type != ET_EXEC) {
+		pr_err("Not an ELF executable.\n");
+		goto error;
+	} else if (!elf_info->proghdrs) {
+		pr_err("No ELF program header.\n");
+		goto error;
+	}
+
+	for (i = 0; i < ehdr->e_phnum; i++) {
+		/*
+		 * Kexec does not support loading interpreters.
+		 * In addition this check keeps us from attempting
+		 * to kexec ordinay executables.
+		 */
+		if (elf_info->proghdrs[i].p_type == PT_INTERP) {
+			pr_err("Requires an ELF interpreter.\n");
+			goto error;
+		}
+	}
+
+	return 0;
+error:
+	elf_free_info(elf_info);
+	return -ENOEXEC;
+}
+
+static int elf64_probe(const char *buf, unsigned long len)
+{
+	struct elfhdr ehdr;
+	struct elf_info elf_info;
+	int ret;
+
+	ret = build_elf_exec_info(buf, len, &ehdr, &elf_info);
+	if (ret)
+		return ret;
+
+	elf_free_info(&elf_info);
+
+	return elf_check_arch(&ehdr) ? 0 : -ENOEXEC;
+}
+
+static bool find_debug_console(void *fdt, int chosen_node)
+{
+	int len;
+	int console_node;
+	const void *prop, *colon;
+
+	prop = fdt_getprop(fdt, chosen_node, "stdout-path", &len);
+	if (prop == NULL) {
+		if (len == -FDT_ERR_NOTFOUND) {
+			prop = fdt_getprop(fdt, chosen_node, "linux,stdout-path",
+					   &len);
+			if (prop == NULL) {
+				pr_debug("Unable to find [linux,]stdout-path.\n");
+				return false;
+			}
+		} else {
+			pr_debug("Error finding console: %s\n",
+				 fdt_strerror(len));
+			return false;
+		}
+	}
+
+	/*
+	 * stdout-path can have a ':' separating the path from device-specific
+	 * information, so we should only consider what's before it.
+	 */
+	colon = strchr(prop, ':');
+	if (colon != NULL)
+		len = colon - prop;
+	else
+		len -= 1;	/* Ignore the terminating NUL. */
+
+	console_node = fdt_path_offset_namelen(fdt, prop, len);
+	if (console_node < 0) {
+		pr_debug("Error finding console: %s\n",
+			 fdt_strerror(console_node));
+		return false;
+	}
+
+	if (fdt_node_check_compatible(fdt, console_node, "hvterm1") == 0)
+		return true;
+	else if (fdt_node_check_compatible(fdt, console_node,
+					   "hvterm-protocol") == 0)
+		return true;
+
+	return false;
+}
+
+static int setup_purgatory(struct kimage *image, struct elf_info *kernel_info,
+			   void *fdt, unsigned long kernel_load_addr,
+			   unsigned long fdt_load_addr, unsigned long stack_top,
+			   int debug)
+{
+	int ret, tree_node;
+	const void *prop;
+	unsigned long opal_base, opal_entry;
+	uint64_t toc;
+	unsigned int *slave_code, master_entry;
+	struct elf_info purg_info;
+
+	/* Get the slave code from the new kernel and put it in purgatory. */
+	slave_code = kmalloc(SLAVE_CODE_SIZE, GFP_KERNEL);
+	if (!slave_code)
+		return -ENOMEM;
+	ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
+					     slave_code, SLAVE_CODE_SIZE, true);
+	if (ret) {
+		kfree(slave_code);
+		return ret;
+	}
+	master_entry = slave_code[0];
+	memcpy(slave_code,
+	       kernel_info->buffer + kernel_info->proghdrs[0].p_offset,
+	       SLAVE_CODE_SIZE);
+	slave_code[0] = master_entry;
+	ret = kexec_purgatory_get_set_symbol(image, "purgatory_start",
+					     slave_code, SLAVE_CODE_SIZE,
+					     false);
+	kfree(slave_code);
+
+	ret = kexec_purgatory_get_set_symbol(image, "kernel", &kernel_load_addr,
+					     sizeof(kernel_load_addr), false);
+	if (ret)
+		return ret;
+	ret = kexec_purgatory_get_set_symbol(image, "dt_offset", &fdt_load_addr,
+					     sizeof(fdt_load_addr), false);
+	if (ret)
+		return ret;
+
+	tree_node = fdt_path_offset(fdt, "/ibm,opal");
+	if (tree_node >= 0) {
+		prop = fdt_getprop(fdt, tree_node, "opal-base-address", NULL);
+		if (!prop) {
+			pr_err("OPAL address not found in the device tree.\n");
+			return -EINVAL;
+		}
+		opal_base = fdt64_to_cpu((const fdt64_t *) prop);
+
+		prop = fdt_getprop(fdt, tree_node, "opal-entry-address", NULL);
+		if (!prop) {
+			pr_err("OPAL address not found in the device tree.\n");
+			return -EINVAL;
+		}
+		opal_entry = fdt64_to_cpu((const fdt64_t *) prop);
+
+		ret = kexec_purgatory_get_set_symbol(image, "opal_base",
+						     &opal_base,
+						     sizeof(opal_base), false);
+		if (ret)
+			return ret;
+		ret = kexec_purgatory_get_set_symbol(image, "opal_entry",
+						     &opal_entry,
+						     sizeof(opal_entry), false);
+		if (ret)
+			return ret;
+	}
+
+	ret = kexec_purgatory_get_set_symbol(image, "stack", &stack_top,
+					     sizeof(stack_top), false);
+	if (ret)
+		return ret;
+
+	elf_init_elf_info(image->purgatory_info.ehdr,
+			  image->purgatory_info.sechdrs, &purg_info);
+	toc = my_r2(&purg_info);
+	ret = kexec_purgatory_get_set_symbol(image, "my_toc", &toc, sizeof(toc),
+					     false);
+	if (ret)
+		return ret;
+	pr_debug("Purgatory TOC is at 0x%llx\n", toc);
+
+	ret = kexec_purgatory_get_set_symbol(image, "debug", &debug,
+					     sizeof(debug), false);
+	if (ret)
+		return ret;
+	if (!debug)
+		pr_debug("Disabling purgatory output.\n");
+
+	return 0;
+}
+
+/**
+ * elf_exec_load - load ELF executable image
+ * @lowest_load_addr:	On return, will be the address where the first PT_LOAD
+ *			section will be loaded in memory.
+ *
+ * Return:
+ * 0 on success, negative value on failure.
+ */
+static int elf_exec_load(struct kimage *image, struct elfhdr *ehdr,
+			 struct elf_info *elf_info,
+			 unsigned long *lowest_load_addr)
+{
+	unsigned long base = 0, lowest_addr = UINT_MAX;
+	int ret;
+	size_t i;
+
+	/* Read in the PT_LOAD segments. */
+	for (i = 0; i < ehdr->e_phnum; i++) {
+		unsigned long load_addr;
+		size_t size;
+		const struct elf_phdr *phdr;
+
+		phdr = &elf_info->proghdrs[i];
+		if (phdr->p_type != PT_LOAD)
+			continue;
+
+		size = phdr->p_filesz;
+		if (size > phdr->p_memsz)
+			size = phdr->p_memsz;
+
+		ret = kexec_add_buffer(image,
+				       (char *) elf_info->buffer + phdr->p_offset,
+				       size, phdr->p_memsz, phdr->p_align,
+				       phdr->p_paddr + base, ppc64_rma_size,
+				       false, &load_addr);
+		if (ret)
+			goto out;
+
+		if (load_addr < lowest_addr)
+			lowest_addr = load_addr;
+	}
+
+	/* Update entry point to reflect new load address. */
+	ehdr->e_entry += base;
+
+	*lowest_load_addr = lowest_addr;
+	ret = 0;
+ out:
+	return ret;
+}
+
+void *elf64_load(struct kimage *image, char *kernel_buf,
+		 unsigned long kernel_len, char *initrd,
+		 unsigned long initrd_len, char *cmdline,
+		 unsigned long cmdline_len)
+{
+	int i;
+	int ret = 0, chosen_node;
+	unsigned int fdt_size;
+	unsigned long kernel_load_addr, purgatory_load_addr;
+	unsigned long initrd_load_addr, fdt_load_addr, stack_top;
+	uint64_t oldfdt_addr;
+	void *fdt;
+	const void *prop;
+	struct elfhdr ehdr;
+	struct elf_info elf_info;
+	struct fdt_reserve_entry *rsvmap;
+
+	ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
+	if (ret)
+		goto out;
+
+	ret = elf_exec_load(image, &ehdr, &elf_info, &kernel_load_addr);
+	if (ret)
+		goto out;
+
+	pr_debug("Loaded the kernel at 0x%lx\n", kernel_load_addr);
+
+	ret = kexec_load_purgatory(image, 0, ppc64_rma_size, true,
+				   &purgatory_load_addr);
+	if (ret) {
+		pr_err("Loading purgatory failed.\n");
+		goto out;
+	}
+
+	pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
+
+	fdt_size = fdt_totalsize(initial_boot_params) * 2;
+	fdt = kmalloc(fdt_size, GFP_KERNEL);
+	if (!fdt) {
+		pr_err("Not enough memory for the device tree.\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
+	if (ret < 0) {
+		pr_err("Error setting up the new device tree.\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Remove memory reservation for the current device tree. */
+	oldfdt_addr = __pa(initial_boot_params);
+	for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+		uint64_t rsv_start, rsv_size;
+
+		ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
+		if (ret) {
+			pr_err("Malformed device tree.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		if (rsv_start == oldfdt_addr &&
+		    rsv_size == fdt_totalsize(initial_boot_params)) {
+			ret = fdt_del_mem_rsv(fdt, i);
+			if (ret) {
+				pr_err("Error deleting fdt reservation.\n");
+				ret = -EINVAL;
+				goto out;
+			}
+			pr_debug("Removed old device tree reservation.\n");
+
+			break;
+		}
+	}
+
+	chosen_node = fdt_path_offset(fdt, "/chosen");
+	if (chosen_node < 0) {
+		pr_err("Malformed device tree: /chosen not found.\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/* Did we boot using an initrd? */
+	prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
+	if (prop) {
+		uint64_t tmp_start, tmp_end, tmp_size, tmp_sizepg;
+
+		tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+		prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
+		if (!prop) {
+			pr_err("Malformed device tree.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+		tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
+
+		/*
+		 * kexec reserves exact initrd size, while firmware may
+		 * reserve a multiple of PAGE_SIZE, so check for both.
+		 */
+		tmp_size = tmp_end - tmp_start;
+		tmp_sizepg = round_up(tmp_size, PAGE_SIZE);
+
+		/* Remove memory reservation for the current initrd. */
+		for (i = 0; i < fdt_num_mem_rsv(fdt); i++) {
+			uint64_t rsv_start, rsv_size;
+
+			ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
+			if (ret) {
+				pr_err("Malformed device tree.\n");
+				ret = -EINVAL;
+				goto out;
+			}
+
+			if (rsv_start == tmp_start &&
+			    (rsv_size == tmp_size || rsv_size == tmp_sizepg)) {
+				ret = fdt_del_mem_rsv(fdt, i);
+				if (ret) {
+					pr_err("Error deleting fdt reservation.\n");
+					ret = -EINVAL;
+					goto out;
+				}
+				pr_debug("Removed old initrd reservation.\n");
+
+				/* fdt was modified, offsets may have changed. */
+				chosen_node = fdt_path_offset(fdt, "/chosen");
+				if (chosen_node < 0) {
+					pr_err("Malformed device tree.\n");
+					ret = -EINVAL;
+					goto out;
+				}
+
+				break;
+			}
+		}
+
+		/* If there's no new initrd, delete the old initrd's info. */
+		if (initrd == NULL) {
+			ret = fdt_delprop(fdt, chosen_node, "linux,initrd-start");
+			if (ret) {
+				pr_err("Error deleting linux,initrd-start.\n");
+				ret = -EINVAL;
+				goto out;
+			}
+
+			ret = fdt_delprop(fdt, chosen_node, "linux,initrd-end");
+			if (ret) {
+				pr_err("Error deleting linux,initrd-end.\n");
+				ret = -EINVAL;
+				goto out;
+			}
+		}
+	}
+
+	if (initrd != NULL) {
+		ret = kexec_add_buffer(image, initrd, initrd_len, initrd_len,
+				       PAGE_SIZE, 0, ppc64_rma_size, false,
+				       &initrd_load_addr);
+		if (ret)
+			goto out;
+
+		pr_debug("Loaded initrd at 0x%lx\n", initrd_load_addr);
+
+		ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-start",
+				      initrd_load_addr);
+		if (ret < 0) {
+			pr_err("Error setting up the new device tree.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+		/* initrd-end is the first address after the initrd image. */
+		ret = fdt_setprop_u64(fdt, chosen_node, "linux,initrd-end",
+				      initrd_load_addr + initrd_len);
+		if (ret < 0) {
+			pr_err("Error setting up the new device tree.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
+		if (ret) {
+			pr_err("Error reserving initrd memory: %s\n",
+			       fdt_strerror(ret));
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (cmdline_len) {
+		ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline);
+		if (ret < 0) {
+			pr_err("Error setting up the new device tree.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+	} else {
+		ret = fdt_delprop(fdt, chosen_node, "bootargs");
+		if (ret && ret != -FDT_ERR_NOTFOUND) {
+			pr_err("Error deleting bootargs.\n");
+			ret = -EINVAL;
+			goto out;
+		}
+	}
+
+	ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
+	if (ret) {
+		pr_err("Error setting up the new device tree.\n");
+		ret = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * Documentation/devicetree/booting-without-of.txt says we need to
+	 * add a reservation entry for the device tree block, but
+	 * early_init_fdt_reserve_self reserves the memory even if there's no
+	 * such entry. We'll add a reservation entry anyway, to be safe and
+	 * compliant.
+	 *
+	 * Use dummy values, we will correct them in a moment.
+	 */
+	ret = fdt_add_mem_rsv(fdt, 1, 1);
+	if (ret) {
+		pr_err("Error reserving device tree memory: %s\n",
+		       fdt_strerror(ret));
+		ret = -EINVAL;
+		goto out;
+	}
+	fdt_pack(fdt);
+
+	ret = kexec_add_buffer(image, fdt, fdt_size, fdt_size, PAGE_SIZE, 0,
+			       ppc64_rma_size, true, &fdt_load_addr);
+	if (ret)
+		goto out;
+
+	/*
+	 * Fix fdt reservation, now that we now where it will be loaded
+	 * and how big it is.
+	 */
+	rsvmap = fdt + fdt_off_mem_rsvmap(fdt);
+	i = fdt_num_mem_rsv(fdt) - 1;
+	rsvmap[i].address = cpu_to_fdt64(fdt_load_addr);
+	rsvmap[i].size = cpu_to_fdt64(fdt_totalsize(fdt));
+
+	pr_debug("Loaded device tree at 0x%lx\n", fdt_load_addr);
+
+	ret = kexec_locate_mem_hole(image, PURGATORY_STACK_SIZE, PAGE_SIZE, 0,
+				    ppc64_rma_size, true, &stack_top);
+	if (ret) {
+		pr_err("Couldn't find free memory for the purgatory stack.\n");
+		ret = -ENOMEM;
+		goto out;
+	}
+	stack_top = stack_top + PURGATORY_STACK_SIZE - 1;
+	pr_debug("Purgatory stack is at 0x%lx\n", stack_top);
+
+	ret = setup_purgatory(image, &elf_info, fdt, kernel_load_addr,
+			      fdt_load_addr, stack_top,
+			      find_debug_console(fdt, chosen_node));
+	if (ret)
+		pr_err("Error setting up the purgatory.\n");
+
+out:
+	elf_free_info(&elf_info);
+
+	/* Make kimage_file_post_load_cleanup free the fdt buffer for us. */
+	return ret ? ERR_PTR(ret) : fdt;
+}
+
+struct kexec_file_ops kexec_elf64_ops = {
+	.probe = elf64_probe,
+	.load = elf64_load,
+};
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index b242f2293a6e..b96e420b43bb 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -18,6 +18,7 @@
 #include <linux/kernel.h>
 #include <linux/cpu.h>
 #include <linux/hardirq.h>
+#include <linux/memblock.h>
 
 #include <asm/page.h>
 #include <asm/current.h>
@@ -30,9 +31,12 @@
 #include <asm/smp.h>
 #include <asm/hw_breakpoint.h>
 #include <asm/asm-prototypes.h>
+#include <asm/kexec_elf_64.h>
 
 #ifdef CONFIG_KEXEC_FILE
-static struct kexec_file_ops *kexec_file_loaders[] = { };
+static struct kexec_file_ops *kexec_file_loaders[] = {
+	&kexec_elf64_ops,
+};
 #endif
 
 #ifdef CONFIG_PPC_BOOK3E
@@ -476,4 +480,84 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image)
 
 	return image->fops->cleanup(image->image_loader_data);
 }
+
+/**
+ * arch_kexec_walk_mem - call func(data) for each unreserved memory block
+ * @kbuf:	Context info for the search. Also passed to @func.
+ * @func:	Function to call for each memory block.
+ *
+ * This function is used by kexec_add_buffer and kexec_locate_mem_hole
+ * to find unreserved memory to load kexec segments into.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int arch_kexec_walk_mem(struct kexec_buf *kbuf, int (*func)(u64, u64, void *))
+{
+	int ret = 0;
+	u64 i;
+	phys_addr_t mstart, mend;
+
+	if (kbuf->top_down) {
+		for_each_free_mem_range_reverse(i, NUMA_NO_NODE, 0,
+						&mstart, &mend, NULL) {
+			ret = func(mstart, mend, kbuf);
+			if (ret)
+				break;
+		}
+	} else {
+		for_each_free_mem_range(i, NUMA_NO_NODE, 0, &mstart, &mend,
+					NULL) {
+			ret = func(mstart, mend, kbuf);
+			if (ret)
+				break;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * arch_kexec_apply_relocations_add - apply purgatory relocations
+ * @ehdr:	Pointer to ELF headers.
+ * @sechdrs:	Pointer to section headers.
+ * @relsec:	Section index of SHT_RELA section.
+ *
+ * Elf64_Shdr.sh_offset has been modified to keep the pointer to the section
+ * contents, while Elf64_Shdr.sh_addr points to the final address of the
+ * section in memory.
+ */
+int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
+				     Elf64_Shdr *sechdrs, unsigned int relsec)
+{
+	/* Section containing the relocation entries. */
+	Elf64_Shdr *rel_section = &sechdrs[relsec];
+	const Elf64_Rela *rela = (const Elf64_Rela *) rel_section->sh_offset;
+	unsigned int num_rela = rel_section->sh_size / sizeof(Elf64_Rela);
+	/* Section to which relocations apply. */
+	Elf64_Shdr *target_section = &sechdrs[rel_section->sh_info];
+	/* Associated symbol table. */
+	Elf64_Shdr *symtabsec = &sechdrs[rel_section->sh_link];
+	void *syms_base = (void *) symtabsec->sh_offset;
+	void *loc_base = (void *) target_section->sh_offset;
+	Elf64_Addr addr_base = target_section->sh_addr;
+	struct elf_info elf_info;
+	const char *strtab;
+
+	if (symtabsec->sh_link >= ehdr->e_shnum) {
+		/* Invalid strtab section number */
+		pr_err("Invalid string table section index %d\n",
+		       symtabsec->sh_link);
+		return -ENOEXEC;
+	}
+	/* String table for the associated symbol table. */
+	strtab = (const char *) sechdrs[symtabsec->sh_link].sh_offset;
+
+	elf_init_elf_info(ehdr, sechdrs, &elf_info);
+
+	return elf64_apply_relocate_add(&elf_info, strtab, rela, num_rela,
+					syms_base, loc_base, addr_base,
+					true, true, "kexec purgatory");
+}
 #endif /* CONFIG_KEXEC_FILE */
diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c
index 7f3b17bcac05..f486f8eded24 100644
--- a/arch/powerpc/kernel/module_64.c
+++ b/arch/powerpc/kernel/module_64.c
@@ -442,6 +442,9 @@ int restore_r2(u32 *instruction, const char *obj_name)
  * When this function is called, the module is already at its final location in
  * memory, so Elf64_Shdr.sh_addr can be used for accessing the section
  * contents as well as the base address for relocations.
+ *
+ * Also, simplify_symbols already changed all symbols' st_value members
+ * to absolute addresses.
  */
 int apply_relocate_add(Elf64_Shdr *sechdrs,
 		       const char *strtab,
@@ -471,7 +474,7 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
 
 	return elf64_apply_relocate_add(&me->arch.elf_info, strtab, rela,
 					num_rela, syms_base, (void *) addr_base,
-					addr_base, me->name);
+					addr_base, false, false, me->name);
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
-- 
1.9.1

[PATCH v3 9/9] powerpc: Add purgatory for kexec_file_load implementation.

[Thiago Jung Bauermann]

This purgatory implementation comes from kexec-tools, almost unchanged.

The only changes were that the sha256_regions global variable was
renamed to sha_regions to match what kexec_file_load expects, and to
use the sha256.c file from x86's purgatory to avoid adding yet another
SHA-256 implementation.

Also, some formatting warnings found by checkpatch.pl were fixed.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 arch/powerpc/Makefile                     |   4 +
 arch/powerpc/purgatory/.gitignore         |   2 +
 arch/powerpc/purgatory/Makefile           |  36 +++++++
 arch/powerpc/purgatory/console-ppc64.c    |  38 +++++++
 arch/powerpc/purgatory/crashdump-ppc64.h  |  42 ++++++++
 arch/powerpc/purgatory/crashdump_backup.c |  36 +++++++
 arch/powerpc/purgatory/crtsavres.S        |   5 +
 arch/powerpc/purgatory/hvCall.S           |  27 +++++
 arch/powerpc/purgatory/hvCall.h           |   8 ++
 arch/powerpc/purgatory/kexec-sha256.h     |  11 ++
 arch/powerpc/purgatory/ppc64_asm.h        |  20 ++++
 arch/powerpc/purgatory/printf.c           | 164 ++++++++++++++++++++++++++++++
 arch/powerpc/purgatory/purgatory-ppc64.c  |  41 ++++++++
 arch/powerpc/purgatory/purgatory-ppc64.h  |   6 ++
 arch/powerpc/purgatory/purgatory.c        |  62 +++++++++++
 arch/powerpc/purgatory/purgatory.h        |  11 ++
 arch/powerpc/purgatory/sha256.c           |   6 ++
 arch/powerpc/purgatory/sha256.h           |   1 +
 arch/powerpc/purgatory/string.S           |   1 +
 arch/powerpc/purgatory/v2wrap.S           | 134 ++++++++++++++++++++++++
 20 files changed, 655 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 709a22a3e824..293322855cce 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -249,6 +249,7 @@ core-y				+= arch/powerpc/kernel/ \
 core-$(CONFIG_XMON)		+= arch/powerpc/xmon/
 core-$(CONFIG_KVM) 		+= arch/powerpc/kvm/
 core-$(CONFIG_PERF_EVENTS)	+= arch/powerpc/perf/
+core-$(CONFIG_KEXEC_FILE)	+= arch/powerpc/purgatory/
 
 drivers-$(CONFIG_OPROFILE)	+= arch/powerpc/oprofile/
 
@@ -370,6 +371,9 @@ archclean:
 	$(Q)$(MAKE) $(clean)=$(boot)
 
 archprepare: checkbin
+ifeq ($(CONFIG_KEXEC_FILE),y)
+	$(Q)$(MAKE) $(build)=arch/powerpc/purgatory arch/powerpc/purgatory/kexec-purgatory.c
+endif
 
 # Use the file '.tmp_gas_check' for binutils tests, as gas won't output
 # to stdout and these checks are run even on install targets.
diff --git a/arch/powerpc/purgatory/.gitignore b/arch/powerpc/purgatory/.gitignore
new file mode 100644
index 000000000000..e9e66f178a6d
--- /dev/null
+++ b/arch/powerpc/purgatory/.gitignore
@@ -0,0 +1,2 @@
+kexec-purgatory.c
+purgatory.ro
diff --git a/arch/powerpc/purgatory/Makefile b/arch/powerpc/purgatory/Makefile
new file mode 100644
index 000000000000..63daf95e5703
--- /dev/null
+++ b/arch/powerpc/purgatory/Makefile
@@ -0,0 +1,36 @@
+purgatory-y := purgatory.o printf.o string.o v2wrap.o hvCall.o \
+		purgatory-ppc64.o console-ppc64.o crashdump_backup.o \
+		crtsavres.o sha256.o
+
+targets += $(purgatory-y)
+PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y))
+
+LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostartfiles \
+			-nostdlib -nodefaultlibs
+targets += purgatory.ro
+
+# Default KBUILD_CFLAGS can have -pg option set when FTRACE is enabled. That
+# in turn leaves some undefined symbols like __fentry__ in purgatory and not
+# sure how to relocate those. Like kexec-tools, use custom flags.
+
+KBUILD_CFLAGS := -Wall -Wstrict-prototypes -fno-strict-aliasing \
+		-fno-zero-initialized-in-bss -fno-builtin -ffreestanding \
+		-fno-PIC -fno-PIE -fno-stack-protector  -fno-exceptions \
+		-msoft-float -MD -Os
+KBUILD_CFLAGS += -m$(CONFIG_WORD_SIZE)
+
+$(obj)/purgatory.ro: $(PURGATORY_OBJS) FORCE
+		$(call if_changed,ld)
+
+targets += kexec-purgatory.c
+
+CMD_BIN2C = $(objtree)/scripts/basic/bin2c
+quiet_cmd_bin2c = BIN2C   $@
+      cmd_bin2c = $(CMD_BIN2C) kexec_purgatory < $< > $@
+
+$(obj)/kexec-purgatory.c: $(obj)/purgatory.ro FORCE
+	$(call if_changed,bin2c)
+	@:
+
+
+obj-$(CONFIG_KEXEC_FILE)	+= kexec-purgatory.o
diff --git a/arch/powerpc/purgatory/console-ppc64.c b/arch/powerpc/purgatory/console-ppc64.c
new file mode 100644
index 000000000000..3d07be0b5d08
--- /dev/null
+++ b/arch/powerpc/purgatory/console-ppc64.c
@@ -0,0 +1,38 @@
+/*
+ * kexec: Linux boots Linux
+ *
+ * Created by: Mohan Kumar M (mohan@in.ibm.com)
+ *
+ * Copyright (C) IBM Corporation, 2005. All rights reserved
+ *
+ * Code taken from kexec-tools.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "hvCall.h"
+#include <asm/byteorder.h>
+
+extern int debug;
+
+void putchar(int c)
+{
+	char buff[8];
+	unsigned long *lbuf = (unsigned long *)buff;
+
+	if (!debug) /* running on non pseries */
+		return;
+
+	if (c == '\n')
+		putchar('\r');
+
+	buff[0] = c;
+	plpar_hcall_norets(H_PUT_TERM_CHAR, 0, 1, __cpu_to_be64(*lbuf), 0);
+}
diff --git a/arch/powerpc/purgatory/crashdump-ppc64.h b/arch/powerpc/purgatory/crashdump-ppc64.h
new file mode 100644
index 000000000000..90064b49ebfe
--- /dev/null
+++ b/arch/powerpc/purgatory/crashdump-ppc64.h
@@ -0,0 +1,42 @@
+#ifndef CRASHDUMP_PPC64_H
+#define CRASHDUMP_PPC64_H
+
+#include <linux/types.h>
+
+struct kexec_info;
+int load_crashdump_segments(struct kexec_info *info, char *mod_cmdline,
+				uint64_t max_addr, unsigned long min_base);
+void add_usable_mem_rgns(unsigned long long base, unsigned long long size);
+
+#define PAGE_OFFSET     0xC000000000000000ULL
+#define KERNELBASE      PAGE_OFFSET
+#define VMALLOCBASE     0xD000000000000000ULL
+
+#define __pa(x)         ((unsigned long)(x)-PAGE_OFFSET)
+#define MAXMEM          (-KERNELBASE-VMALLOCBASE)
+
+#define COMMAND_LINE_SIZE       512 /* from kernel */
+/* Backup Region, First 64K of System RAM. */
+#define BACKUP_SRC_START    0x0000
+#define BACKUP_SRC_END      0xffff
+#define BACKUP_SRC_SIZE     (BACKUP_SRC_END - BACKUP_SRC_START + 1)
+
+#define KDUMP_BACKUP_LIMIT	BACKUP_SRC_SIZE
+
+#define KERNEL_RUN_AT_ZERO_MAGIC 0x72756e30	/* "run0" */
+
+extern uint64_t crash_base;
+extern uint64_t crash_size;
+extern uint64_t memory_limit;
+extern unsigned int rtas_base;
+extern unsigned int rtas_size;
+extern uint64_t opal_base;
+extern uint64_t opal_size;
+
+uint64_t lmb_size;
+unsigned int num_of_lmbs;
+
+#define DRCONF_ADDR	0
+#define DRCONF_FLAGS	20
+
+#endif /* CRASHDUMP_PPC64_H */
diff --git a/arch/powerpc/purgatory/crashdump_backup.c b/arch/powerpc/purgatory/crashdump_backup.c
new file mode 100644
index 000000000000..11ccafdcc9ad
--- /dev/null
+++ b/arch/powerpc/purgatory/crashdump_backup.c
@@ -0,0 +1,36 @@
+/*
+ * kexec: Linux boots Linux
+ *
+ * Created by: Mohan Kumar M (mohan@in.ibm.com)
+ *
+ * Copyright (C) IBM Corporation, 2005. All rights reserved
+ *
+ * Code taken from kexec-tools.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "../boot/string.h"
+#include "crashdump-ppc64.h"
+
+extern unsigned long backup_start;
+
+/* Backup first 32KB of memory to backup region reserved by kexec */
+void crashdump_backup_memory(void)
+{
+	void *dest, *src;
+
+	src = (void *)BACKUP_SRC_START;
+
+	if (backup_start) {
+		dest = (void *)(backup_start);
+		memcpy(dest, src, BACKUP_SRC_SIZE);
+	}
+}
diff --git a/arch/powerpc/purgatory/crtsavres.S b/arch/powerpc/purgatory/crtsavres.S
new file mode 100644
index 000000000000..5d17e1c0d575
--- /dev/null
+++ b/arch/powerpc/purgatory/crtsavres.S
@@ -0,0 +1,5 @@
+#ifndef CONFIG_CC_OPTIMIZE_FOR_SIZE
+#define CONFIG_CC_OPTIMIZE_FOR_SIZE 1
+#endif
+
+#include "../lib/crtsavres.S"
diff --git a/arch/powerpc/purgatory/hvCall.S b/arch/powerpc/purgatory/hvCall.S
new file mode 100644
index 000000000000..a96c4898f1d8
--- /dev/null
+++ b/arch/powerpc/purgatory/hvCall.S
@@ -0,0 +1,27 @@
+/*
+ * This file contains the generic function to perform a call to the
+ * pSeries LPAR hypervisor.
+ *
+ * Taken from linux/arch/powerpc/platforms/pseries/hvCall.S
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+#include "ppc64_asm.h"
+
+#define HVSC	.long 0x44000022
+.text
+	.machine ppc64
+.globl DOTSYM(plpar_hcall_norets)
+DOTSYM(plpar_hcall_norets):
+	or	6,6,6			# medium low priority
+        mfcr	0
+        stw	0,8(1)
+
+        HVSC 				/* invoke the hypervisor */
+
+        lwz	0,8(1)
+        mtcrf	0xff,0
+        blr                             /* return r3 = status */
diff --git a/arch/powerpc/purgatory/hvCall.h b/arch/powerpc/purgatory/hvCall.h
new file mode 100644
index 000000000000..187e24d8b964
--- /dev/null
+++ b/arch/powerpc/purgatory/hvCall.h
@@ -0,0 +1,8 @@
+#ifndef HVCALL_H
+#define HVCALL_H
+
+#define H_PUT_TERM_CHAR	0x58
+
+long plpar_hcall_norets(unsigned long opcode, ...);
+
+#endif
diff --git a/arch/powerpc/purgatory/kexec-sha256.h b/arch/powerpc/purgatory/kexec-sha256.h
new file mode 100644
index 000000000000..4418ed02c052
--- /dev/null
+++ b/arch/powerpc/purgatory/kexec-sha256.h
@@ -0,0 +1,11 @@
+#ifndef KEXEC_SHA256_H
+#define KEXEC_SHA256_H
+
+struct kexec_sha_region {
+	unsigned long start;
+	unsigned long len;
+};
+
+#define SHA256_REGIONS 16
+
+#endif /* KEXEC_SHA256_H */
diff --git a/arch/powerpc/purgatory/ppc64_asm.h b/arch/powerpc/purgatory/ppc64_asm.h
new file mode 100644
index 000000000000..95d721718237
--- /dev/null
+++ b/arch/powerpc/purgatory/ppc64_asm.h
@@ -0,0 +1,20 @@
+/*
+ * ppc64_asm.h - common defines for PPC64 assembly parts
+ *
+ * Code taken from kexec-tools.
+ *
+ * This source code is licensed under the GNU General Public License,
+ * Version 2.  See the file COPYING for more details.
+ */
+
+#include <asm/types.h>
+
+/*
+ * ABIv1 requires dot symbol while ABIv2 does not.
+ */
+#ifdef PPC64_ELF_ABI_v2
+#define DOTSYM(a)	a
+#else
+#define GLUE(a, b)	a##b
+#define DOTSYM(a)	GLUE(., a)
+#endif
diff --git a/arch/powerpc/purgatory/printf.c b/arch/powerpc/purgatory/printf.c
new file mode 100644
index 000000000000..c5f425b55fd5
--- /dev/null
+++ b/arch/powerpc/purgatory/printf.c
@@ -0,0 +1,164 @@
+/*
+ * Code taken from kexec-tools.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdarg.h>
+#include "purgatory.h"
+#include "../boot/string.h"
+
+#define CHAR_BIT 8
+
+/*
+ * Output
+ * =============================================================================
+ */
+
+#define LONG_LONG_SHIFT  ((int)((sizeof(unsigned long long)*CHAR_BIT) - 4))
+#define LONG_SHIFT  ((int)((sizeof(unsigned long)*CHAR_BIT) - 4))
+#define INT_SHIFT   ((int)((sizeof(unsigned int)*CHAR_BIT) - 4))
+#define SHRT_SHIFT  ((int)((sizeof(unsigned short)*CHAR_BIT) - 4))
+#define CHAR_SHIFT  ((int)((sizeof(unsigned char)*CHAR_BIT) - 4))
+
+/**************************************************************************
+PRINTF and friends
+
+	Formats:
+		%x	- 4 bytes int (8 hex digits, lower case)
+		%X	- 4 bytes int (8 hex digits, upper case)
+		%lx     - 8 bytes long (16 hex digits, lower case)
+		%lX     - 8 bytes long (16 hex digits, upper case)
+		%hx	- 2 bytes int (4 hex digits, lower case)
+		%hX	- 2 bytes int (4 hex digits, upper case)
+		%hhx	- 1 byte int (2 hex digits, lower case)
+		%hhX	- 1 byte int (2 hex digits, upper case)
+			- optional # prefixes 0x or 0X
+		%d	- decimal int
+		%c	- char
+		%s	- string
+	Note: width specification not supported
+**************************************************************************/
+void vsprintf(char *buffer, const char *fmt, va_list args)
+{
+	char *p;
+
+	for ( ; *fmt != '\0'; ++fmt) {
+		if (*fmt != '%') {
+			if (buffer)
+				*buffer++ = *fmt;
+			else
+				putchar(*fmt);
+			continue;
+		}
+		if (*++fmt == 's') {
+			for (p = va_arg(args, char *); *p != '\0'; p++)
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
+		} else {	/* Length of item is bounded */
+			char tmp[40], *q = tmp;
+			int shift = INT_SHIFT;
+
+			if (*fmt == 'L') {
+				shift = LONG_LONG_SHIFT;
+				fmt++;
+			} else if (*fmt == 'l') {
+				shift = LONG_SHIFT;
+				fmt++;
+			} else if (*fmt == 'h') {
+				shift = SHRT_SHIFT;
+				fmt++;
+				if (*fmt == 'h') {
+					shift = CHAR_SHIFT;
+					fmt++;
+				}
+			}
+
+			/*
+			 * Before each format q points to tmp buffer
+			 * After each format q points past end of item
+			 */
+			if ((*fmt | 0x20) == 'x') {
+				/* With x86 gcc, sizeof(long) == sizeof(int) */
+				unsigned long long h;
+				int ncase;
+
+				if (shift > LONG_SHIFT)
+					h = va_arg(args, unsigned long long);
+				else if (shift > INT_SHIFT)
+					h = va_arg(args, unsigned long);
+				else
+					h = va_arg(args, unsigned int);
+
+				ncase = (*fmt & 0x20);
+				for ( ; shift >= 0; shift -= 4)
+					*q++ = "0123456789ABCDEF"[(h >> shift) & 0xF] | ncase;
+			} else if (*fmt == 'd') {
+				char *r;
+				long i;
+
+				if (shift > LONG_SHIFT)
+					i = va_arg(args, long long);
+				else if (shift > INT_SHIFT)
+					i = va_arg(args, long);
+				else
+					i = va_arg(args, int);
+
+				if (i < 0) {
+					*q++ = '-';
+					i = -i;
+				}
+				p = q;		/* save beginning of digits */
+				do {
+					*q++ = '0' + (i % 10);
+					i /= 10;
+				} while (i);
+				/* reverse digits, stop in middle */
+				r = q;		/* don't alter q */
+				while (--r > p) {
+					i = *r;
+					*r = *p;
+					*p++ = i;
+				}
+			} else if (*fmt == 'c')
+				*q++ = va_arg(args, int);
+			else
+				*q++ = *fmt;
+			/* now output the saved string */
+			for (p = tmp; p < q; ++p)
+				if (buffer)
+					*buffer++ = *p;
+				else
+					putchar(*p);
+		}
+	}
+	if (buffer)
+		*buffer = '\0';
+}
+
+void sprintf(char *buffer, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(buffer, fmt, args);
+	va_end(args);
+}
+
+void printf(const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	vsprintf(0, fmt, args);
+	va_end(args);
+}
diff --git a/arch/powerpc/purgatory/purgatory-ppc64.c b/arch/powerpc/purgatory/purgatory-ppc64.c
new file mode 100644
index 000000000000..0be65a424ab1
--- /dev/null
+++ b/arch/powerpc/purgatory/purgatory-ppc64.c
@@ -0,0 +1,41 @@
+/*
+ * kexec: Linux boots Linux
+ *
+ * Created by: Mohan Kumar M (mohan@in.ibm.com)
+ *
+ * Copyright (C) IBM Corporation, 2005. All rights reserved
+ *
+ * Code taken from kexec-tools.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "purgatory.h"
+#include "purgatory-ppc64.h"
+
+unsigned int panic_kernel = 0;
+unsigned long backup_start = 0;
+unsigned long stack = 0;
+unsigned long dt_offset = 0;
+unsigned long my_toc = 0;
+unsigned long kernel = 0;
+unsigned int debug = 0;
+unsigned long opal_base = 0;
+unsigned long opal_entry = 0;
+
+void setup_arch(void)
+{
+}
+
+void post_verification_setup_arch(void)
+{
+	if (panic_kernel)
+		crashdump_backup_memory();
+}
diff --git a/arch/powerpc/purgatory/purgatory-ppc64.h b/arch/powerpc/purgatory/purgatory-ppc64.h
new file mode 100644
index 000000000000..52eaf4394c48
--- /dev/null
+++ b/arch/powerpc/purgatory/purgatory-ppc64.h
@@ -0,0 +1,6 @@
+#ifndef PURGATORY_PPC64_H
+#define PURGATORY_PPC64_H
+
+void crashdump_backup_memory(void);
+
+#endif /* PURGATORY_PPC64_H */
diff --git a/arch/powerpc/purgatory/purgatory.c b/arch/powerpc/purgatory/purgatory.c
new file mode 100644
index 000000000000..5b006d685cf2
--- /dev/null
+++ b/arch/powerpc/purgatory/purgatory.c
@@ -0,0 +1,62 @@
+/*
+ * Code taken from kexec-tools.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation (version 2 of the License).
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include "purgatory.h"
+#include "sha256.h"
+#include "../boot/string.h"
+#include "kexec-sha256.h"
+
+struct kexec_sha_region sha_regions[SHA256_REGIONS] = {};
+u8 sha256_digest[SHA256_DIGEST_SIZE] = { 0 };
+
+int verify_sha256_digest(void)
+{
+	struct kexec_sha_region *ptr, *end;
+	u8 digest[SHA256_DIGEST_SIZE];
+	size_t i;
+	struct sha256_state sctx;
+
+	sha256_init(&sctx);
+	end = &sha_regions[sizeof(sha_regions)/sizeof(sha_regions[0])];
+	for (ptr = sha_regions; ptr < end; ptr++)
+		sha256_update(&sctx, (uint8_t *)(ptr->start), ptr->len);
+	sha256_final(&sctx, digest);
+
+	if (memcmp(digest, sha256_digest, sizeof(digest)) != 0) {
+		printf("sha256 digests do not match :(\n");
+		printf("       digest: ");
+		for (i = 0; i < sizeof(digest); i++)
+			printf("%hhx ", digest[i]);
+		printf("\n");
+
+		printf("sha256_digest: ");
+		for (i = 0; i < sizeof(sha256_digest); i++)
+			printf("%hhx ", sha256_digest[i]);
+
+		printf("\n");
+		return 1;
+	}
+	return 0;
+}
+
+void purgatory(void)
+{
+	printf("I'm in purgatory\n");
+	setup_arch();
+	if (verify_sha256_digest()) {
+		/* loop forever */
+		for (;;)
+			;
+	}
+	post_verification_setup_arch();
+}
diff --git a/arch/powerpc/purgatory/purgatory.h b/arch/powerpc/purgatory/purgatory.h
new file mode 100644
index 000000000000..788ce4930a30
--- /dev/null
+++ b/arch/powerpc/purgatory/purgatory.h
@@ -0,0 +1,11 @@
+#ifndef PURGATORY_H
+#define PURGATORY_H
+
+void putchar(int ch);
+void sprintf(char *buffer, const char *fmt, ...)
+	__attribute__ ((format (printf, 2, 3)));
+void printf(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
+void setup_arch(void);
+void post_verification_setup_arch(void);
+
+#endif /* PURGATORY_H */
diff --git a/arch/powerpc/purgatory/sha256.c b/arch/powerpc/purgatory/sha256.c
new file mode 100644
index 000000000000..6abee1877d56
--- /dev/null
+++ b/arch/powerpc/purgatory/sha256.c
@@ -0,0 +1,6 @@
+#include "../boot/string.h"
+
+/* Avoid including x86's boot/string.h in sha256.c. */
+#define BOOT_STRING_H
+
+#include "../../x86/purgatory/sha256.c"
diff --git a/arch/powerpc/purgatory/sha256.h b/arch/powerpc/purgatory/sha256.h
new file mode 100644
index 000000000000..72818f3a207e
--- /dev/null
+++ b/arch/powerpc/purgatory/sha256.h
@@ -0,0 +1 @@
+#include "../../x86/purgatory/sha256.h"
diff --git a/arch/powerpc/purgatory/string.S b/arch/powerpc/purgatory/string.S
new file mode 100644
index 000000000000..3a1e23ff4017
--- /dev/null
+++ b/arch/powerpc/purgatory/string.S
@@ -0,0 +1 @@
+#include "../boot/string.S"
diff --git a/arch/powerpc/purgatory/v2wrap.S b/arch/powerpc/purgatory/v2wrap.S
new file mode 100644
index 000000000000..c9a981c39a78
--- /dev/null
+++ b/arch/powerpc/purgatory/v2wrap.S
@@ -0,0 +1,134 @@
+#
+#  kexec: Linux boots Linux
+#
+#  Copyright (C) 2004 - 2005, Milton D Miller II, IBM Corporation
+#  Copyright (C) 2006, Mohan Kumar M (mohan@in.ibm.com), IBM Corporation
+#
+# Code taken from kexec-tools.
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License as published by
+#  the Free Software Foundation (version 2 of the License).
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+
+#include "ppc64_asm.h"
+
+# v2wrap.S
+# a wrapper to call purgatory code to backup first
+# 32kB of first kernel into the backup region
+# reserved by kexec-tools.
+# Invokes ppc64 kernel with the expected arguments
+# of kernel(device-tree, phys-offset, 0)
+
+#
+# calling convention:
+#   r3 = physical number of this cpu (all cpus)
+#   r4 = address of this chunk (master only)
+# master enters at purgatory_start (aka first byte of this chunk)
+# slaves (additional cpus), if any, enter a copy of the
+# first 0x100 bytes of this code relocated to 0x0
+#
+# in other words,
+#   a copy of the first 0x100 bytes of this code is copied to 0
+#   and the slaves are sent to address 0x60
+#   with r3 = their physical cpu number.
+
+#define LOADADDR(rn,name) \
+	lis     rn,name##@highest;      \
+	ori     rn,rn,name##@higher;    \
+	rldicr  rn,rn,32,31;            \
+	oris    rn,rn,name##@h;         \
+	ori     rn,rn,name##@l
+
+	.machine ppc64
+	.align 8
+	.globl purgatory_start
+purgatory_start:	b	master
+	.org purgatory_start + 0x5c     # ABI: possible run_at_load flag at 0x5c
+	.globl run_at_load
+run_at_load:
+	.long 0
+	.size run_at_load, . - run_at_load
+	.org purgatory_start + 0x60     # ABI: slaves start at 60 with r3=phys
+slave:	b $
+	.org purgatory_start + 0x100    # ABI: end of copied region
+	.size purgatory_start, . - purgatory_start
+
+#
+# The above 0x100 bytes at purgatory_start are replaced with the
+# code from the kernel (or next stage) by kexec/arch/ppc64/kexec-elf-ppc64.c
+#
+
+master:
+	or	1,1,1		# low priority to let other threads catchup
+	isync
+	mr      17,3            # save cpu id to r17
+	mr      15,4            # save physical address in reg15
+
+	LOADADDR(6,my_toc)
+	ld      2,0(6)          #setup toc
+
+	LOADADDR(6,stack)
+	ld      1,0(6)          #setup stack
+
+	subi    1,1,112
+	bl      DOTSYM(purgatory)
+	nop
+
+	or	3,3,3		# ok now to high priority, lets boot
+	lis	6,0x1
+	mtctr	6		# delay a bit for slaves to catch up
+83:	bdnz	83b		# before we overwrite 0-100 again
+
+	LOADADDR(16, dt_offset)
+	ld      3,0(16)         # load device-tree address
+	mr      16,3            # save dt address in reg16
+#ifdef __BIG_ENDIAN__
+	lwz     6,20(3)         # fetch version number
+#else
+	li	4,20
+	lwbrx	6,3,4		# fetch BE version number
+#endif
+	cmpwi   0,6,2           # v2 ?
+	blt     80f
+#ifdef __BIG_ENDIAN__
+	stw     17,28(3)        # save my cpu number as boot_cpu_phys
+#else
+	li	4,28
+	stwbrx	17,3,4		# Store my cpu as BE value
+#endif
+80:
+	LOADADDR(6,opal_base)	# For OPAL early debug
+	ld      8,0(6)          # load the OPAL base address in r8
+	LOADADDR(6,opal_entry)	# For OPAL early debug
+	ld      9,0(6)          # load the OPAL entry address in r9
+	LOADADDR(6,kernel)
+	ld      4,0(6)          # load the kernel address
+	LOADADDR(6,run_at_load) # the load flag
+	lwz	7,0(6)		# possibly patched by kexec-elf-ppc64
+	stw	7,0x5c(4)	# and patch it into the kernel
+	mr      3,16            # restore dt address
+
+	mfmsr	5
+	andi.	10,5,1		# test MSR_LE
+	bne	little_endian
+
+	li	5,0		# r5 will be 0 for kernel
+	mtctr	4		# prepare branch to
+	bctr			# start kernel
+
+little_endian:			# book3s-only
+	mtsrr0	4		# prepare branch to
+
+	clrrdi	5,5,1		# clear MSR_LE
+	mtsrr1	5
+
+	li	5,0		# r5 will be 0 for kernel
+
+				# skip cache flush, do we care?
+
+	rfid			# update MSR and start kernel
-- 
1.9.1

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h |  4 ++++
>  kernel/kexec_file.c   | 66 ++++++++++++++++++++++++++++++++++++++-------------
>  2 files changed, 53 insertions(+), 17 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..4ca6f5f95d66 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -227,6 +227,10 @@ extern asmlinkage long sys_kexec_load(unsigned long entry,
>  					struct kexec_segment __user *segments,
>  					unsigned long flags);
>  extern int kernel_kexec(void);
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +			  unsigned long align, unsigned long min_addr,
> +			  unsigned long max_addr, bool top_down,
> +			  unsigned long *addr);
>  extern int kexec_add_buffer(struct kimage *image, char *buffer,
>  			    unsigned long bufsz, unsigned long memsz,
>  			    unsigned long buf_align, unsigned long buf_min,
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..85a515511925 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,46 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
> + * @image:	kexec image being updated.
> + * @size:	Memory size.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down	Find the highest free memory region?
> + * @addr	On success, will have start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> +			  unsigned long align, unsigned long min_addr,
> +			  unsigned long max_addr, bool top_down,
> +			  unsigned long *addr)
> +{
> +	int ret;
> +	struct kexec_buf buf;
> +
> +	memset(&buf, 0, sizeof(struct kexec_buf));
> +	buf.image = image;
> +
> +	buf.memsz = size;
> +	buf.buf_align = align;
> +	buf.buf_min = min_addr;
> +	buf.buf_max = max_addr;
> +	buf.top_down = top_down;

Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
will be natural to passing a kexec_buf pointer intead of passing all
these arguments in kexec_locate_mem_hole.

kbuf.mem can be used for addr.

> +
> +	ret = arch_kexec_walk_mem(&buf, locate_mem_hole_callback);
> +	if (ret != 1) {
> +		/* A suitable memory range could not be found for buffer */
> +		return -EADDRNOTAVAIL;
> +	}
> +
> +	*addr = buf.mem;
> +
> +	return 0;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -460,8 +500,8 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  {
>  
>  	struct kexec_segment *ksegment;
> -	struct kexec_buf buf, *kbuf;
>  	int ret;
> +	unsigned long addr, align, size;
>  
>  	/* Currently adding segment this way is allowed only in file mode */
>  	if (!image->file_mode)
> @@ -482,29 +522,21 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  		return -EINVAL;
>  	}
>  
> -	memset(&buf, 0, sizeof(struct kexec_buf));
> -	kbuf = &buf;
> -	kbuf->image = image;
> -
> -	kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
> -	kbuf->buf_align = max(buf_align, PAGE_SIZE);
> -	kbuf->buf_min = buf_min;
> -	kbuf->buf_max = buf_max;
> -	kbuf->top_down = top_down;
> +	size = ALIGN(memsz, PAGE_SIZE);
> +	align = max(buf_align, PAGE_SIZE);
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -	if (ret != 1) {
> -		/* A suitable memory range could not be found for buffer */
> -		return -EADDRNOTAVAIL;
> -	}
> +	ret = kexec_locate_mem_hole(image, size, align, buf_min, buf_max,
> +				    top_down, &addr);
> +	if (ret)
> +		return ret;
>  
>  	/* Found a suitable memory range */
>  	ksegment = &image->segment[image->nr_segments];
>  	ksegment->kbuf = buffer;
>  	ksegment->bufsz = bufsz;
> -	ksegment->mem = kbuf->mem;
> -	ksegment->memsz = kbuf->memsz;
> +	ksegment->mem = addr;
> +	ksegment->memsz = size;
>  	image->nr_segments++;
>  	*load_addr = ksegment->mem;
>  	return 0;

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

The patch looks good, but could the subject be more specific?

For example just like the first sentence of the patch descriotion:
Allow architectures to specify their own memory walking function

On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> Allow architectures to specify different memory walking functions for
> kexec_add_buffer. Intel uses iomem to track reserved memory ranges,
> but PowerPC uses the memblock subsystem.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h   | 19 ++++++++++++++++++-
>  kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
>  kernel/kexec_internal.h | 14 --------------
>  3 files changed, 40 insertions(+), 23 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..3d91bcfc180d 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,24 @@ struct kexec_file_ops {
>  	kexec_verify_sig_t *verify_sig;
>  #endif
>  };
> -#endif
> +
> +/*
> + * Keeps track of buffer parameters as provided by caller for requesting
> + * memory placement of buffer.
> + */
> +struct kexec_buf {
> +	struct kimage *image;
> +	unsigned long mem;
> +	unsigned long memsz;
> +	unsigned long buf_align;
> +	unsigned long buf_min;
> +	unsigned long buf_max;
> +	bool top_down;		/* allocate from top of memory hole */
> +};
> +
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *));
> +#endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
>  	kimage_entry_t head;
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b6eec7527e9f..b1f1f6402518 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
>  	return locate_mem_hole_bottom_up(start, end, kbuf);
>  }
>  
> +/**
> + * arch_kexec_walk_mem - call func(data) on free memory regions
> + * @kbuf:	Context info for the search. Also passed to @func.
> + * @func:	Function to call for each memory region.
> + *
> + * Return: The memory walk will stop when func returns a non-zero value
> + * and that value will be returned. If all free regions are visited without
> + * func returning non-zero, then zero will be returned.
> + */
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *))
> +{
> +	if (kbuf->image->type == KEXEC_TYPE_CRASH)
> +		return walk_iomem_res_desc(crashk_res.desc,
> +					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> +					   crashk_res.start, crashk_res.end,
> +					   kbuf, func);
> +	else
> +		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	if (image->type == KEXEC_TYPE_CRASH)
> -		ret = walk_iomem_res_desc(crashk_res.desc,
> -				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> -				crashk_res.start, crashk_res.end, kbuf,
> -				locate_mem_hole_callback);
> -	else
> -		ret = walk_system_ram_res(0, -1, kbuf,
> -					  locate_mem_hole_callback);
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
>  	if (ret != 1) {
>  		/* A suitable memory range could not be found for buffer */
>  		return -EADDRNOTAVAIL;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index eefd5bf960c2..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,20 +20,6 @@ struct kexec_sha_region {
>  	unsigned long len;
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> - */
> -struct kexec_buf {
> -	struct kimage *image;
> -	unsigned long mem;
> -	unsigned long memsz;
> -	unsigned long buf_align;
> -	unsigned long buf_min;
> -	unsigned long buf_max;
> -	bool top_down;		/* allocate from top of memory hole */
> -};
> -
>  void kimage_file_post_load_cleanup(struct kimage *image);
>  #else /* CONFIG_KEXEC_FILE */
>  static inline void kimage_file_post_load_cleanup(struct kimage *image) { }

Thanks
Dave

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Balbir Singh]

On Tue, 21 Jun 2016 16:48:32 -0300
Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> wrote:

> Hello,
> 
> This patch series implements the kexec_file_load system call on
> PowerPC.
> 
> This system call moves the reading of the kernel, initrd and the
> device tree from the userspace kexec tool to the kernel. This is
> needed if you want to do one or both of the following:
> 
> 1. only allow loading of signed kernels.
> 2. "measure" (i.e., record the hashes of) the kernel, initrd, kernel
>    command line and other boot inputs for the Integrity Measurement
>    Architecture subsystem.
> 
> The above are the functions kexec already has built into
> kexec_file_load. Yesterday I posted a set of patches which allows a
> third feature:
> 
> 3. have IMA pass-on its event log (where integrity measurements are
>    registered) accross kexec to the second kernel, so that the event
>    history is preserved.

OK.. and this is safe? Do both the kernels need to be signed by the
same certificate?


Balbir Singh

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Thiago Jung Bauermann]

Hello Balbir,

Am Mittwoch, 22 Juni 2016, 23:29:46 schrieb Balbir Singh:
> On Tue, 21 Jun 2016 16:48:32 -0300
> Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> wrote:
> > This patch series implements the kexec_file_load system call on
> > PowerPC.
> > 
> > This system call moves the reading of the kernel, initrd and the
> > device tree from the userspace kexec tool to the kernel. This is
> > needed if you want to do one or both of the following:
> > 
> > 1. only allow loading of signed kernels.
> > 2. "measure" (i.e., record the hashes of) the kernel, initrd, kernel
> > 
> >    command line and other boot inputs for the Integrity Measurement
> >    Architecture subsystem.
> > 
> > The above are the functions kexec already has built into
> > kexec_file_load. Yesterday I posted a set of patches which allows a
> > third feature:
> > 
> > 3. have IMA pass-on its event log (where integrity measurements are
> > 
> >    registered) accross kexec to the second kernel, so that the event
> >    history is preserved.
> 
> OK.. and this is safe? Do both the kernels need to be signed by the
> same certificate?

They don't. The integrity of the event log (assuming that is what you mean 
by "this" in "this is safe") is guaranteed by the TPM device. Each event in 
the measurement list extends a PCR and records its PCR value. It is 
cryptographically guaranteed that if you replay the PCR extends recorded in 
the event log and in the end of the process they match the current PCR 
values in the TPM device, then that event log is correct.

The kernel signature serves to ensure that you only run kernels from an 
authorized provider. It doesn't play a role in integrity assurance, which 
aims to verify that the machine is really running the code it says it is 
running. As I understand it, at least. It's a bit subtle and I could be 
missing something...

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Mittwoch, 22 Juni 2016, 18:20:47 schrieb Dave Young:
> The patch looks good, but could the subject be more specific?
> 
> For example just like the first sentence of the patch descriotion:
> Allow architectures to specify their own memory walking function

Ok, What about this? I also changed the description to refer to x86 arch
instead of Intel arch.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


Subject: [PATCH 2/9] kexec_file: Allow arch-specific memory walking for
 kexec_add_buffer

Allow architectures to specify a different memory walking function for
kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
PowerPC uses the memblock subsystem.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h   | 19 ++++++++++++++++++-
 kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
 kernel/kexec_internal.h | 14 --------------
 3 files changed, 40 insertions(+), 23 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e8acb2b43dd9..3d91bcfc180d 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -146,7 +146,24 @@ struct kexec_file_ops {
 	kexec_verify_sig_t *verify_sig;
 #endif
 };
-#endif
+
+/*
+ * Keeps track of buffer parameters as provided by caller for requesting
+ * memory placement of buffer.
+ */
+struct kexec_buf {
+	struct kimage *image;
+	unsigned long mem;
+	unsigned long memsz;
+	unsigned long buf_align;
+	unsigned long buf_min;
+	unsigned long buf_max;
+	bool top_down;		/* allocate from top of memory hole */
+};
+
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *));
+#endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
 	kimage_entry_t head;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b6eec7527e9f..b1f1f6402518 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 	return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
+/**
+ * arch_kexec_walk_mem - call func(data) on free memory regions
+ * @kbuf:	Context info for the search. Also passed to @func.
+ * @func:	Function to call for each memory region.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *))
+{
+	if (kbuf->image->type == KEXEC_TYPE_CRASH)
+		return walk_iomem_res_desc(crashk_res.desc,
+					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+					   crashk_res.start, crashk_res.end,
+					   kbuf, func);
+	else
+		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	if (image->type == KEXEC_TYPE_CRASH)
-		ret = walk_iomem_res_desc(crashk_res.desc,
-				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
-				crashk_res.start, crashk_res.end, kbuf,
-				locate_mem_hole_callback);
-	else
-		ret = walk_system_ram_res(0, -1, kbuf,
-					  locate_mem_hole_callback);
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
 	if (ret != 1) {
 		/* A suitable memory range could not be found for buffer */
 		return -EADDRNOTAVAIL;
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index eefd5bf960c2..4cef7e4706b0 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -20,20 +20,6 @@ struct kexec_sha_region {
 	unsigned long len;
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
- */
-struct kexec_buf {
-	struct kimage *image;
-	unsigned long mem;
-	unsigned long memsz;
-	unsigned long buf_align;
-	unsigned long buf_min;
-	unsigned long buf_max;
-	bool top_down;		/* allocate from top of memory hole */
-};
-
 void kimage_file_post_load_cleanup(struct kimage *image);
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
-- 
1.9.1

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > +/**
> > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > purgatory + * @image:	kexec image being updated.
> > + * @size:	Memory size.
> > + * @align:	Minimum alignment needed.
> > + * @min_addr:	Minimum starting address.
> > + * @max_addr:	Maximum end address.
> > + * @top_down	Find the highest free memory region?
> > + * @addr	On success, will have start address of the memory region
> > found.
> > + *
> > + * Return: 0 on success, negative errno on error.
> > + */
> > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > +			  unsigned long align, unsigned long min_addr,
> > +			  unsigned long max_addr, bool top_down,
> > +			  unsigned long *addr)
> > +{
> > +	int ret;
> > +	struct kexec_buf buf;
> > +
> > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > +	buf.image = image;
> > +
> > +	buf.memsz = size;
> > +	buf.buf_align = align;
> > +	buf.buf_min = min_addr;
> > +	buf.buf_max = max_addr;
> > +	buf.top_down = top_down;
> 
> Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> will be natural to passing a kexec_buf pointer intead of passing all
> these arguments in kexec_locate_mem_hole.
> 
> kbuf.mem can be used for addr.

Ok. What about this version?
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
 kexec_add_buffer.

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h | 12 +++++++++---
 kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
 2 files changed, 29 insertions(+), 8 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 3d91bcfc180d..e8b099da47f5 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -147,9 +147,14 @@ struct kexec_file_ops {
 #endif
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
+/**
+ * struct kexec_buf - parameters for finding a place for a buffer in memory
+ * @image:	kexec image in which memory to search.
+ * @size:	Memory size for the buffer.
+ * @align:	Minimum alignment needed.
+ * @min_addr:	Minimum starting address.
+ * @max_addr:	Maximum end address.
+ * @top_down:	Find the highest free memory region?
  */
 struct kexec_buf {
 	struct kimage *image;
@@ -163,6 +168,7 @@ struct kexec_buf {
 
 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 			       int (*func)(u64, u64, void *));
+int kexec_locate_mem_hole(struct kexec_buf *kbuf);
 #endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b1f1f6402518..445d66add8ca 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @kbuf:	Parameters for the memory search.
+ *
+ * On success, kbuf->mem will have the start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kexec_buf *kbuf)
+{
+	int ret;
+
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
+
+	return ret == 1 ? 0 : -EADDRNOTAVAIL;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(kbuf);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
-- 
1.9.1

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Balbir Singh]

On 23/06/16 03:02, Thiago Jung Bauermann wrote:
> Hello Balbir,
>
Hi Thiago
 
>>> 3. have IMA pass-on its event log (where integrity measurements are
>>>
>>>    registered) accross kexec to the second kernel, so that the event
>>>    history is preserved.
>>
>> OK.. and this is safe? Do both the kernels need to be signed by the
>> same certificate?
> 
> They don't. The integrity of the event log (assuming that is what you mean 
> by "this" in "this is safe") is guaranteed by the TPM device. Each event in 
> the measurement list extends a PCR and records its PCR value. It is 
> cryptographically guaranteed that if you replay the PCR extends recorded in 
> the event log and in the end of the process they match the current PCR 
> values in the TPM device, then that event log is correct.


What I meant was how does the new kernel know that the old kernel did not
cheat while passing on the values? I presume because we trust that kernel
via a signature.


and

How do we know the new kernel is safe to load - I guess via a signature that
the new kernel is signed with (assuming it is present in the key ring).

Balbir Singh

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 06/22/16 at 08:30pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 22 Juni 2016, 18:20:47 schrieb Dave Young:
> > The patch looks good, but could the subject be more specific?
> > 
> > For example just like the first sentence of the patch descriotion:
> > Allow architectures to specify their own memory walking function
> 
> Ok, What about this? I also changed the description to refer to x86 arch
> instead of Intel arch.

It looks good to me.

Thanks
Dave

> 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 2/9] kexec_file: Allow arch-specific memory walking for
>  kexec_add_buffer
> 
> Allow architectures to specify a different memory walking function for
> kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
> PowerPC uses the memblock subsystem.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h   | 19 ++++++++++++++++++-
>  kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
>  kernel/kexec_internal.h | 14 --------------
>  3 files changed, 40 insertions(+), 23 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..3d91bcfc180d 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,24 @@ struct kexec_file_ops {
>  	kexec_verify_sig_t *verify_sig;
>  #endif
>  };
> -#endif
> +
> +/*
> + * Keeps track of buffer parameters as provided by caller for requesting
> + * memory placement of buffer.
> + */
> +struct kexec_buf {
> +	struct kimage *image;
> +	unsigned long mem;
> +	unsigned long memsz;
> +	unsigned long buf_align;
> +	unsigned long buf_min;
> +	unsigned long buf_max;
> +	bool top_down;		/* allocate from top of memory hole */
> +};
> +
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *));
> +#endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
>  	kimage_entry_t head;
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b6eec7527e9f..b1f1f6402518 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
>  	return locate_mem_hole_bottom_up(start, end, kbuf);
>  }
>  
> +/**
> + * arch_kexec_walk_mem - call func(data) on free memory regions
> + * @kbuf:	Context info for the search. Also passed to @func.
> + * @func:	Function to call for each memory region.
> + *
> + * Return: The memory walk will stop when func returns a non-zero value
> + * and that value will be returned. If all free regions are visited without
> + * func returning non-zero, then zero will be returned.
> + */
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *))
> +{
> +	if (kbuf->image->type == KEXEC_TYPE_CRASH)
> +		return walk_iomem_res_desc(crashk_res.desc,
> +					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> +					   crashk_res.start, crashk_res.end,
> +					   kbuf, func);
> +	else
> +		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	if (image->type == KEXEC_TYPE_CRASH)
> -		ret = walk_iomem_res_desc(crashk_res.desc,
> -				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> -				crashk_res.start, crashk_res.end, kbuf,
> -				locate_mem_hole_callback);
> -	else
> -		ret = walk_system_ram_res(0, -1, kbuf,
> -					  locate_mem_hole_callback);
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
>  	if (ret != 1) {
>  		/* A suitable memory range could not be found for buffer */
>  		return -EADDRNOTAVAIL;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index eefd5bf960c2..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,20 +20,6 @@ struct kexec_sha_region {
>  	unsigned long len;
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> - */
> -struct kexec_buf {
> -	struct kimage *image;
> -	unsigned long mem;
> -	unsigned long memsz;
> -	unsigned long buf_align;
> -	unsigned long buf_min;
> -	unsigned long buf_max;
> -	bool top_down;		/* allocate from top of memory hole */
> -};
> -
>  void kimage_file_post_load_cleanup(struct kimage *image);
>  #else /* CONFIG_KEXEC_FILE */
>  static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
> -- 
> 1.9.1
> 
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 
> 

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/22/16 at 08:34pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> > On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > > +/**
> > > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > > purgatory + * @image:	kexec image being updated.
> > > + * @size:	Memory size.
> > > + * @align:	Minimum alignment needed.
> > > + * @min_addr:	Minimum starting address.
> > > + * @max_addr:	Maximum end address.
> > > + * @top_down	Find the highest free memory region?
> > > + * @addr	On success, will have start address of the memory region
> > > found.
> > > + *
> > > + * Return: 0 on success, negative errno on error.
> > > + */
> > > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > > +			  unsigned long align, unsigned long min_addr,
> > > +			  unsigned long max_addr, bool top_down,
> > > +			  unsigned long *addr)
> > > +{
> > > +	int ret;
> > > +	struct kexec_buf buf;
> > > +
> > > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > > +	buf.image = image;
> > > +
> > > +	buf.memsz = size;
> > > +	buf.buf_align = align;
> > > +	buf.buf_min = min_addr;
> > > +	buf.buf_max = max_addr;
> > > +	buf.top_down = top_down;
> > 
> > Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> > will be natural to passing a kexec_buf pointer intead of passing all
> > these arguments in kexec_locate_mem_hole.
> > 
> > kbuf.mem can be used for addr.
> 
> Ok. What about this version?
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
>  kexec_add_buffer.
> 
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h | 12 +++++++++---
>  kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
>  2 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..e8b099da47f5 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -147,9 +147,14 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @size:	Memory size for the buffer.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down:	Find the highest free memory region?

Above parameter comments should go to previous patch.
Other than that it looks good.

Thanks
Dave
>   */
>  struct kexec_buf {
>  	struct kimage *image;
> @@ -163,6 +168,7 @@ struct kexec_buf {
>  
>  int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  			       int (*func)(u64, u64, void *));
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf);
>  #endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..445d66add8ca 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
> + * @kbuf:	Parameters for the memory search.
> + *
> + * On success, kbuf->mem will have the start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf)
> +{
> +	int ret;
> +
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> +
> +	return ret == 1 ? 0 : -EADDRNOTAVAIL;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -	if (ret != 1) {
> -		/* A suitable memory range could not be found for buffer */
> -		return -EADDRNOTAVAIL;
> -	}
> +	ret = kexec_locate_mem_hole(kbuf);
> +	if (ret)
> +		return ret;
>  
>  	/* Found a suitable memory range */
>  	ksegment = &image->segment[image->nr_segments];
> -- 
> 1.9.1
> 
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
> 
> 

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

----- Original Message -----
From: "Dave Young" <dyoung@redhat.com>
To: "Thiago Jung Bauermann" <bauerman@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, "Eric Biederman" <ebiederm@xmission.com>
Sent: Thursday, June 23, 2016 10:30:52 AM
Subject: Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

On 06/22/16 at 08:34pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 22 Juni 2016, 18:18:01 schrieb Dave Young:
> > On 06/21/16 at 04:48pm, Thiago Jung Bauermann wrote:
> > > +/**
> > > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > > purgatory + * @image:	kexec image being updated.
> > > + * @size:	Memory size.
> > > + * @align:	Minimum alignment needed.
> > > + * @min_addr:	Minimum starting address.
> > > + * @max_addr:	Maximum end address.
> > > + * @top_down	Find the highest free memory region?
> > > + * @addr	On success, will have start address of the memory region
> > > found.
> > > + *
> > > + * Return: 0 on success, negative errno on error.
> > > + */
> > > +int kexec_locate_mem_hole(struct kimage *image, unsigned long size,
> > > +			  unsigned long align, unsigned long min_addr,
> > > +			  unsigned long max_addr, bool top_down,
> > > +			  unsigned long *addr)
> > > +{
> > > +	int ret;
> > > +	struct kexec_buf buf;
> > > +
> > > +	memset(&buf, 0, sizeof(struct kexec_buf));
> > > +	buf.image = image;
> > > +
> > > +	buf.memsz = size;
> > > +	buf.buf_align = align;
> > > +	buf.buf_min = min_addr;
> > > +	buf.buf_max = max_addr;
> > > +	buf.top_down = top_down;
> > 
> > Since patch 2/9 moved kexec_buf from internal header file to kexec.h it
> > will be natural to passing a kexec_buf pointer intead of passing all
> > these arguments in kexec_locate_mem_hole.
> > 
> > kbuf.mem can be used for addr.
> 
> Ok. What about this version?
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
>  kexec_add_buffer.
> 
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h | 12 +++++++++---
>  kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
>  2 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index 3d91bcfc180d..e8b099da47f5 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -147,9 +147,14 @@ struct kexec_file_ops {
>  #endif
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @size:	Memory size for the buffer.
> + * @align:	Minimum alignment needed.
> + * @min_addr:	Minimum starting address.
> + * @max_addr:	Maximum end address.
> + * @top_down:	Find the highest free memory region?

Hmm, hold on. For declaring a struct in a header file, comment should be
just after each fields, like below, your format is for a function instead:
struct pci_slot {
        struct pci_bus *bus;            /* The bus this slot is on */
        struct list_head list;          /* node in list of slots on this bus */
        struct hotplug_slot *hotplug;   /* Hotplug info (migrate over time) */
        unsigned char number;           /* PCI_SLOT(pci_dev->devfn) */
        struct kobject kobj;
};

BTW, what is @size? there's no size field in kexec_buf. I think it is not
necessary to add these comment, they are easy to understand. If you really
want, please rewrite them correctly, for example "image" description is wrong.
It is not only for searching memory only, top_down description is also bad.

Thanks
Dave

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> Hmm, hold on. For declaring a struct in a header file, comment should be
> just after each fields, like below, your format is for a function instead:
> struct pci_slot {
>         struct pci_bus *bus;            /* The bus this slot is on */
>         struct list_head list;          /* node in list of slots on this
> bus */ struct hotplug_slot *hotplug;   /* Hotplug info (migrate over
> time) */ unsigned char number;           /* PCI_SLOT(pci_dev->devfn) */
> struct kobject kobj;
> };

The comment style you mention above is not extractable documentation. The 
style I used is what is described in section "kernel-doc for structs, 
unions, enums, and typedefs" in Documentation/kernel-doc-nano-HOWTO.txt.
 
> BTW, what is @size? there's no size field in kexec_buf. I think it is not
> necessary to add these comment, they are easy to understand. If you really
> want, please rewrite them correctly, for example "image" description is
> wrong. It is not only for searching memory only, top_down description is
> also bad.

Sorry, I moved these comments from kexec_locate_mem_hole but forgot to 
rename the parameters to what they are called in struct kexec_buf. @size 
should have been @memsz (other fields also have wrong names, I'll fix them 
as well). The image description is correct in the context of where struct 
kexec_buf is used and explains what it will be used for in the function 
taking kexec_buf as an argument. It is not meant as a general description of 
the purpose of struct kimage. What is bad about the description of top_down?

I decided to add these comments because struct kexec_buf is now part of the 
kernel API for kexec. kernel-doc-nano-HOWTO.txt says:

> We definitely need kernel-doc formatted documentation for functions
> that are exported to loadable modules using EXPORT_SYMBOL.
> 
> We also look to provide kernel-doc formatted documentation for
> functions externally visible to other kernel files (not marked
> "static").
> 
> We also recommend providing kernel-doc formatted documentation
> for private (file "static") routines, for consistency of kernel
> source code layout.  But this is lower priority and at the
> discretion of the MAINTAINER of that kernel source file.

If you think they are not necessary or just add clutter I can leave them 
out.

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Thiago Jung Bauermann]

Am Donnerstag, 23 Juni 2016, 09:57:51 schrieb Balbir Singh:
> On 23/06/16 03:02, Thiago Jung Bauermann wrote:
> >>> 3. have IMA pass-on its event log (where integrity measurements are
> >>> 
> >>>    registered) accross kexec to the second kernel, so that the event
> >>>    history is preserved.
> >> 
> >> OK.. and this is safe? Do both the kernels need to be signed by the
> >> same certificate?
> > 
> > They don't. The integrity of the event log (assuming that is what you
> > mean by "this" in "this is safe") is guaranteed by the TPM device. Each
> > event in the measurement list extends a PCR and records its PCR value.
> > It is cryptographically guaranteed that if you replay the PCR extends
> > recorded in the event log and in the end of the process they match the
> > current PCR values in the TPM device, then that event log is correct.
> 
> What I meant was how does the new kernel know that the old kernel did not
> cheat while passing on the values? I presume because we trust that kernel
> via a signature.

Sorry, I still don't understand your concern. What kind of cheating? Which 
values? If it's the values in the event log, there's no need to trust the 
old kernel. The new kernel knows that the old kernel didn't pass wrong 
measurement values in the event log because it can recalculate the PCR 
extend operations recorded in the log and compare the results of the replay 
with the current PCR values stored in the TPM device. If they match, then 
the event log is guaranteed to be correct. If they don't match, either the 
memory was corrupted somehow during the kexec process, or the old kernel 
tried to pass a falsified event log.

There's no known way to construct an alternative series of PCR extend 
operations that will result in the same final value in the PCR register of 
the TPM device. If you can do that, you discovered a hash collision attack 
on the SHA-1 or SHA-256 algorithms (depending on which algorithm is being 
used by IMA in the event log). Or a bug in the TPM device implementation.

> and
> 
> How do we know the new kernel is safe to load - I guess via a signature
> that the new kernel is signed with (assuming it is present in the key
> ring).

Correct. That goal is met by signature verification, not by integrity 
assurance.

I'll note that even with both of my patch series there's still code missing 
for kernel signature verification in PowerPC. I believe there's not a file 
format defined yet for how to store a signature in a PowerPC kernel image.

Integrity assurance doesn't depend on kernel signature verification though. 
There's value in both my patch series even without kernel signature 
verification support. They're complementary features.
 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Balbir Singh]

On 24/06/16 02:44, Thiago Jung Bauermann wrote:
> Am Donnerstag, 23 Juni 2016, 09:57:51 schrieb Balbir Singh:
>> On 23/06/16 03:02, Thiago Jung Bauermann wrote:
>>>>> 3. have IMA pass-on its event log (where integrity measurements are
>>>>>
>>>>>    registered) accross kexec to the second kernel, so that the event
>>>>>    history is preserved.
>>>>
>>>> OK.. and this is safe? Do both the kernels need to be signed by the
>>>> same certificate?
>>>
>>> They don't. The integrity of the event log (assuming that is what you
>>> mean by "this" in "this is safe") is guaranteed by the TPM device. Each
>>> event in the measurement list extends a PCR and records its PCR value.
>>> It is cryptographically guaranteed that if you replay the PCR extends
>>> recorded in the event log and in the end of the process they match the
>>> current PCR values in the TPM device, then that event log is correct.
>>
>> What I meant was how does the new kernel know that the old kernel did not
>> cheat while passing on the values? I presume because we trust that kernel
>> via a signature.
> 
> Sorry, I still don't understand your concern. What kind of cheating? Which 
> values? If it's the values in the event log, there's no need to trust the 
> old kernel. The new kernel knows that the old kernel didn't pass wrong 
> measurement values in the event log because it can recalculate the PCR 
> extend operations recorded in the log and compare the results of the replay 
> with the current PCR values stored in the TPM device. If they match, then 
> the event log is guaranteed to be correct. If they don't match, either the 
> memory was corrupted somehow during the kexec process, or the old kernel 
> tried to pass a falsified event log.
> 

Yep, get it/got it. My concern was anything using passed on the values should
compare the results with the current PCR values.

BTW, what do we gain by passing the values if we are relying on the PCR registers
anyway, can't we directly read them off from there? Aren't we going to ready anyway
to compare, what does passing the values gain?

[snip]

>> and
>>
>> How do we know the new kernel is safe to load - I guess via a signature
>> that the new kernel is signed with (assuming it is present in the key
>> ring).
> 
> Correct. That goal is met by signature verification, not by integrity 
> assurance.
> 
> I'll note that even with both of my patch series there's still code missing 
> for kernel signature verification in PowerPC. I believe there's not a file 
> format defined yet for how to store a signature in a PowerPC kernel image.
> 
> Integrity assurance doesn't depend on kernel signature verification though. 
> There's value in both my patch series even without kernel signature 
> verification support. They're complementary features.
>  

Thanks for clarifying

Balbir Singh.

Re: [PATCH v3 0/9] kexec_file_load implementation for PowerPC

[Thiago Jung Bauermann]

Am Freitag, 24 Juni 2016, 08:33:24 schrieb Balbir Singh:
> On 24/06/16 02:44, Thiago Jung Bauermann wrote:
> > Sorry, I still don't understand your concern. What kind of cheating?
> > Which values? If it's the values in the event log, there's no need to
> > trust the old kernel. The new kernel knows that the old kernel didn't
> > pass wrong measurement values in the event log because it can
> > recalculate the PCR extend operations recorded in the log and compare
> > the results of the replay with the current PCR values stored in the TPM
> > device. If they match, then the event log is guaranteed to be correct.
> > If they don't match, either the memory was corrupted somehow during the
> > kexec process, or the old kernel tried to pass a falsified event log.
> 
> Yep, get it/got it. My concern was anything using passed on the values
> should compare the results with the current PCR values.
> 
> BTW, what do we gain by passing the values if we are relying on the PCR
> registers anyway, can't we directly read them off from there? Aren't we
> going to ready anyway to compare, what does passing the values gain?

The PCR values themselves change for reasons that the application/user may 
not care about. For example, just changing the order in which measurements 
are made changes the final value of the PCR, even if all the measurements 
themselves don't change. And in current multi-processor machines this order 
does change at each boot, so you can't rely on two boots of the same machine 
with the same software to have the same PCR values.

Also, you may want to verify only the measurement of one of the components 
and not care about the other components.

With an event log, you can verify the checksum of each measured component 
individually, and the PCR value serves to confirm that the event log is 
correct. Just having the final PCR value without the event log, you don't 
know which measurements were made.

> >> and
> >> 
> >> How do we know the new kernel is safe to load - I guess via a signature
> >> that the new kernel is signed with (assuming it is present in the key
> >> ring).
> > 
> > Correct. That goal is met by signature verification, not by integrity
> > assurance.
> > 
> > I'll note that even with both of my patch series there's still code
> > missing for kernel signature verification in PowerPC. I believe there's
> > not a file format defined yet for how to store a signature in a PowerPC
> > kernel image.
> > 
> > Integrity assurance doesn't depend on kernel signature verification
> > though. There's value in both my patch series even without kernel
> > signature verification support. They're complementary features.
> 
> Thanks for clarifying

Thank you for your interest.

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > Hmm, hold on. For declaring a struct in a header file, comment should be
> > just after each fields, like below, your format is for a function instead:
> > struct pci_slot {
> >         struct pci_bus *bus;            /* The bus this slot is on */
> >         struct list_head list;          /* node in list of slots on this
> > bus */ struct hotplug_slot *hotplug;   /* Hotplug info (migrate over
> > time) */ unsigned char number;           /* PCI_SLOT(pci_dev->devfn) */
> > struct kobject kobj;
> > };
> 
> The comment style you mention above is not extractable documentation. The 
> style I used is what is described in section "kernel-doc for structs, 
> unions, enums, and typedefs" in Documentation/kernel-doc-nano-HOWTO.txt.

You are right and I was wrong!

>  
> > BTW, what is @size? there's no size field in kexec_buf. I think it is not
> > necessary to add these comment, they are easy to understand. If you really
> > want, please rewrite them correctly, for example "image" description is
> > wrong. It is not only for searching memory only, top_down description is
> > also bad.
> 
> Sorry, I moved these comments from kexec_locate_mem_hole but forgot to 
> rename the parameters to what they are called in struct kexec_buf. @size 
> should have been @memsz (other fields also have wrong names, I'll fix them 
> as well). The image description is correct in the context of where struct 
> kexec_buf is used and explains what it will be used for in the function 
> taking kexec_buf as an argument. It is not meant as a general description of 
> the purpose of struct kimage. What is bad about the description of top_down?

It is not clear enough to me, I personally think the original one in
source code is better:
/* allocate from top of memory hole */

> 
> I decided to add these comments because struct kexec_buf is now part of the 
> kernel API for kexec. kernel-doc-nano-HOWTO.txt says:
> 
> > We definitely need kernel-doc formatted documentation for functions
> > that are exported to loadable modules using EXPORT_SYMBOL.
> > 
> > We also look to provide kernel-doc formatted documentation for
> > functions externally visible to other kernel files (not marked
> > "static").
> > 
> > We also recommend providing kernel-doc formatted documentation
> > for private (file "static") routines, for consistency of kernel
> > source code layout.  But this is lower priority and at the
> > discretion of the MAINTAINER of that kernel source file.
> 
> If you think they are not necessary or just add clutter I can leave them 
> out.

I'm fine with either way.

THanks
Dave

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > What is bad about the description of top_down?
> It is not clear enough to me, I personally think the original one in
> source code is better:
> /* allocate from top of memory hole */

Actually I realized there's some discrepancy in how the x86 code uses 
top_down and how I need it to work in powerpc. This may be what is confusing 
about my comment and the existing comment.

x86 always walks memory from bottom to top but if top_down is true, in each 
memory region it will allocate the memory hole in the highest address within 
that region. I don't know why it is done that way, though.

On powerpc, the memory walk itself should be from top to bottom, as well as 
the memory hole allocation within each memory region.

Should I add a separate top_down argument to kexec_locate_mem_hole to 
control if the memory walk should be from top to bottom, and then the 
bottom_up member of struct kexec_buf controls where inside each memory 
region the memory hole will be allocated?

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Montag, 27 Juni 2016, 13:37:58 schrieb Thiago Jung Bauermann:
> Should I add a separate top_down argument to kexec_locate_mem_hole to
> control if the memory walk should be from top to bottom, and then the
> bottom_up member of struct kexec_buf controls where inside each memory
> region the memory hole will be allocated?

Er, "...the bottom_up member of struct kexec_buf..." should read "...the 
top_down member of struct kexec buf...".

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

Please ignore previous reply, I mistakenly send a broken mail without
subject, sorry about it. Resend the reply here.

On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote:
> Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > > What is bad about the description of top_down?
> > It is not clear enough to me, I personally think the original one in
> > source code is better:
> > /* allocate from top of memory hole */
> 
> Actually I realized there's some discrepancy in how the x86 code uses 
> top_down and how I need it to work in powerpc. This may be what is confusing 
> about my comment and the existing comment.
> 
> x86 always walks memory from bottom to top but if top_down is true, in each 
> memory region it will allocate the memory hole in the highest address within 
> that region. I don't know why it is done that way, though.

I think we did not meaning to do this, considering kdump we have only
one crashkernel region for searching (crashk_res) so it is fine.
For kexec maybe changing the walking function to accept top_down is
reasonable.
 
Ccing Vivek see if he can remember something..

> 
> On powerpc, the memory walk itself should be from top to bottom, as well as 
> the memory hole allocation within each memory region.
> 
> Should I add a separate top_down argument to kexec_locate_mem_hole to 
> control if the memory walk should be from top to bottom, and then the 
> bottom_up member of struct kexec_buf controls where inside each memory 
> region the memory hole will be allocated?
> 
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/27/16 at 04:21pm, Dave Young wrote:
> Please ignore previous reply, I mistakenly send a broken mail without
> subject, sorry about it. Resend the reply here.
> 
> On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote:
> > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > > > What is bad about the description of top_down?
> > > It is not clear enough to me, I personally think the original one in
> > > source code is better:
> > > /* allocate from top of memory hole */
> > 
> > Actually I realized there's some discrepancy in how the x86 code uses 
> > top_down and how I need it to work in powerpc. This may be what is confusing 
> > about my comment and the existing comment.
> > 
> > x86 always walks memory from bottom to top but if top_down is true, in each 
> > memory region it will allocate the memory hole in the highest address within 
> > that region. I don't know why it is done that way, though.
> 
> I think we did not meaning to do this, considering kdump we have only
> one crashkernel region for searching (crashk_res) so it is fine.
> For kexec maybe changing the walking function to accept top_down is
> reasonable.
>  
> Ccing Vivek see if he can remember something..
> 
> > 
> > On powerpc, the memory walk itself should be from top to bottom, as well as 
> > the memory hole allocation within each memory region.

What is the particular reason in powerpc for a mandatory top to bottom
walking?

> > 
> > Should I add a separate top_down argument to kexec_locate_mem_hole to 
> > control if the memory walk should be from top to bottom, and then the 
> > bottom_up member of struct kexec_buf controls where inside each memory 
> > region the memory hole will be allocated?

Using one argument for both sounds more reasonable than using a separate
argument for memory walk..

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 23 Juni 2016, 10:25:06 schrieb Dave Young:
> On 06/22/16 at 08:30pm, Thiago Jung Bauermann wrote:
> > Am Mittwoch, 22 Juni 2016, 18:20:47 schrieb Dave Young:
> > > The patch looks good, but could the subject be more specific?
> > > 
> > > For example just like the first sentence of the patch descriotion:
> > > Allow architectures to specify their own memory walking function
> > 
> > Ok, What about this? I also changed the description to refer to x86 arch
> > instead of Intel arch.
> 
> It looks good to me.

This version has the struct kexec_buf documentation comments that were
in patch 3/9. I fixed the names of the struct members, and changed their
descriptions to try to be clearer.
-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


Subject: [PATCH 2/9] kexec_file: Allow arch-specific memory walking for
 kexec_add_buffer

Allow architectures to specify a different memory walking function for
kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
PowerPC uses the memblock subsystem.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h   | 25 ++++++++++++++++++++++++-
 kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
 kernel/kexec_internal.h | 14 --------------
 3 files changed, 46 insertions(+), 23 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e8acb2b43dd9..e16d845d587f 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -146,7 +146,30 @@ struct kexec_file_ops {
 	kexec_verify_sig_t *verify_sig;
 #endif
 };
-#endif
+
+/**
+ * struct kexec_buf - parameters for finding a place for a buffer in memory
+ * @image:	kexec image in which memory to search.
+ * @mem:	On return will have address of the buffer in memory.
+ * @memsz:	Size for the buffer in memory.
+ * @buf_align:	Minimum alignment needed.
+ * @buf_min:	The buffer can't be placed below this address.
+ * @buf_max:	The buffer can't be placed above this address.
+ * @top_down:	Allocate from top of memory.
+ */
+struct kexec_buf {
+	struct kimage *image;
+	unsigned long mem;
+	unsigned long memsz;
+	unsigned long buf_align;
+	unsigned long buf_min;
+	unsigned long buf_max;
+	bool top_down;
+};
+
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *));
+#endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
 	kimage_entry_t head;
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b6eec7527e9f..b1f1f6402518 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 	return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
+/**
+ * arch_kexec_walk_mem - call func(data) on free memory regions
+ * @kbuf:	Context info for the search. Also passed to @func.
+ * @func:	Function to call for each memory region.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *))
+{
+	if (kbuf->image->type == KEXEC_TYPE_CRASH)
+		return walk_iomem_res_desc(crashk_res.desc,
+					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+					   crashk_res.start, crashk_res.end,
+					   kbuf, func);
+	else
+		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	if (image->type == KEXEC_TYPE_CRASH)
-		ret = walk_iomem_res_desc(crashk_res.desc,
-				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
-				crashk_res.start, crashk_res.end, kbuf,
-				locate_mem_hole_callback);
-	else
-		ret = walk_system_ram_res(0, -1, kbuf,
-					  locate_mem_hole_callback);
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
 	if (ret != 1) {
 		/* A suitable memory range could not be found for buffer */
 		return -EADDRNOTAVAIL;
diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
index eefd5bf960c2..4cef7e4706b0 100644
--- a/kernel/kexec_internal.h
+++ b/kernel/kexec_internal.h
@@ -20,20 +20,6 @@ struct kexec_sha_region {
 	unsigned long len;
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
- */
-struct kexec_buf {
-	struct kimage *image;
-	unsigned long mem;
-	unsigned long memsz;
-	unsigned long buf_align;
-	unsigned long buf_min;
-	unsigned long buf_max;
-	bool top_down;		/* allocate from top of memory hole */
-};
-
 void kimage_file_post_load_cleanup(struct kimage *image);
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
-- 
1.9.1

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> On 06/27/16 at 04:21pm, Dave Young wrote:
> > Please ignore previous reply, I mistakenly send a broken mail without
> > subject, sorry about it. Resend the reply here.
> > 
> > On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote:
> > > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> > > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > > > > What is bad about the description of top_down?
> > > > 
> > > > It is not clear enough to me, I personally think the original one in
> > > > source code is better:
> > > > /* allocate from top of memory hole */
> > > 
> > > Actually I realized there's some discrepancy in how the x86 code uses
> > > top_down and how I need it to work in powerpc. This may be what is
> > > confusing about my comment and the existing comment.
> > > 
> > > x86 always walks memory from bottom to top but if top_down is true, in
> > > each memory region it will allocate the memory hole in the highest
> > > address within that region. I don't know why it is done that way,
> > > though.
> > 
> > I think we did not meaning to do this, considering kdump we have only
> > one crashkernel region for searching (crashk_res) so it is fine.
> > For kexec maybe changing the walking function to accept top_down is
> > reasonable.
> > 
> > Ccing Vivek see if he can remember something..
> > 
> > > On powerpc, the memory walk itself should be from top to bottom, as
> > > well as the memory hole allocation within each memory region.
> 
> What is the particular reason in powerpc for a mandatory top to bottom
> walking?

I'm walking unreserved memory ranges, so reservations made low in memory 
(such as the reservation for the initrd) may create a memory hole that is a 
lot lower than the true memory limit where I want to allocate from (768 MB). 
In this situation, allocating at the highest address in the lowest free 
memory range will allocate the buffer very low in memory, and in that case 
top_down doesn't mean much.

Walking memory from lowest to highest address but then allocating memory at 
the highest address inside the memory range is peculiar and surprising. Is 
there a particular reason for it?

If it's an accident and doesn't affect x86, I'd suggest that top_down should
have its expected behavior, which (at least for me) is: allocate from the
highest available memory address within the desired range.

In any case, my patch series allows each architecture to define what
top_down should mean. It doesn't change the behavior in x86, since
the default implementation of arch_kexec_walk_mem ignores
kexec_buf.top_down, and allows powerpc to take top_down into account
when walking memory.

> > > Should I add a separate top_down argument to kexec_locate_mem_hole to
> > > control if the memory walk should be from top to bottom, and then the
> > > bottom_up member of struct kexec_buf controls where inside each memory
> > > region the memory hole will be allocated?
> 
> Using one argument for both sounds more reasonable than using a separate
> argument for memory walk..

I agree. This patch doesn't use a separate top_down argument, it's the same
patch I sent earlier except that the comments to struct kexec_buf are in
patch 2/9. What do you think?

-- 
[]'s
Thiago Jung Bauermann
IBM Linux Technology Center


Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
 kexec_add_buffer.

kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
implementation to find free memory for the purgatory stack.

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: kexec@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/kexec.h |  1 +
 kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index e16d845d587f..2b34e69db679 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -169,6 +169,7 @@ struct kexec_buf {
 
 int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 			       int (*func)(u64, u64, void *));
+int kexec_locate_mem_hole(struct kexec_buf *kbuf);
 #endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index b1f1f6402518..445d66add8ca 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
 		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
+/**
+ * kexec_locate_mem_hole - find free memory to load segment or use in purgatory
+ * @kbuf:	Parameters for the memory search.
+ *
+ * On success, kbuf->mem will have the start address of the memory region found.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_locate_mem_hole(struct kexec_buf *kbuf)
+{
+	int ret;
+
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
+
+	return ret == 1 ? 0 : -EADDRNOTAVAIL;
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
-	if (ret != 1) {
-		/* A suitable memory range could not be found for buffer */
-		return -EADDRNOTAVAIL;
-	}
+	ret = kexec_locate_mem_hole(kbuf);
+	if (ret)
+		return ret;
 
 	/* Found a suitable memory range */
 	ksegment = &image->segment[image->nr_segments];
-- 
1.9.1

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> > On 06/27/16 at 04:21pm, Dave Young wrote:
> > > Please ignore previous reply, I mistakenly send a broken mail without
> > > subject, sorry about it. Resend the reply here.
> > > 
> > > On 06/27/16 at 01:37pm, Thiago Jung Bauermann wrote:
> > > > Am Dienstag, 28 Juni 2016, 00:19:48 schrieb Dave Young:
> > > > > On 06/23/16 at 12:37pm, Thiago Jung Bauermann wrote:
> > > > > > Am Donnerstag, 23 Juni 2016, 01:44:07 schrieb Dave Young:
> > > > > > What is bad about the description of top_down?
> > > > > 
> > > > > It is not clear enough to me, I personally think the original one in
> > > > > source code is better:
> > > > > /* allocate from top of memory hole */
> > > > 
> > > > Actually I realized there's some discrepancy in how the x86 code uses
> > > > top_down and how I need it to work in powerpc. This may be what is
> > > > confusing about my comment and the existing comment.
> > > > 
> > > > x86 always walks memory from bottom to top but if top_down is true, in
> > > > each memory region it will allocate the memory hole in the highest
> > > > address within that region. I don't know why it is done that way,
> > > > though.
> > > 
> > > I think we did not meaning to do this, considering kdump we have only
> > > one crashkernel region for searching (crashk_res) so it is fine.
> > > For kexec maybe changing the walking function to accept top_down is
> > > reasonable.
> > > 
> > > Ccing Vivek see if he can remember something..
> > > 
> > > > On powerpc, the memory walk itself should be from top to bottom, as
> > > > well as the memory hole allocation within each memory region.
> > 
> > What is the particular reason in powerpc for a mandatory top to bottom
> > walking?
> 
> I'm walking unreserved memory ranges, so reservations made low in memory 
> (such as the reservation for the initrd) may create a memory hole that is a 
> lot lower than the true memory limit where I want to allocate from (768 MB). 
> In this situation, allocating at the highest address in the lowest free 
> memory range will allocate the buffer very low in memory, and in that case 
> top_down doesn't mean much.
> 
> Walking memory from lowest to highest address but then allocating memory at 
> the highest address inside the memory range is peculiar and surprising. Is 
> there a particular reason for it?

I do not know if there's some historic reason, personally I think it
should be an accident.

> 
> If it's an accident and doesn't affect x86, I'd suggest that top_down should
> have its expected behavior, which (at least for me) is: allocate from the
> highest available memory address within the desired range.

I tend to agree, but we need test it first to see if it breaks something.

> 
> In any case, my patch series allows each architecture to define what
> top_down should mean. It doesn't change the behavior in x86, since
> the default implementation of arch_kexec_walk_mem ignores
> kexec_buf.top_down, and allows powerpc to take top_down into account
> when walking memory.
> 
> > > > Should I add a separate top_down argument to kexec_locate_mem_hole to
> > > > control if the memory walk should be from top to bottom, and then the
> > > > bottom_up member of struct kexec_buf controls where inside each memory
> > > > region the memory hole will be allocated?
> > 
> > Using one argument for both sounds more reasonable than using a separate
> > argument for memory walk..
> 
> I agree. This patch doesn't use a separate top_down argument, it's the same
> patch I sent earlier except that the comments to struct kexec_buf are in
> patch 2/9. What do you think?

It looks good except one nitpick inline..

> 
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 3/9] kexec_file: Factor out kexec_locate_mem_hole from
>  kexec_add_buffer.
> 
> kexec_locate_mem_hole will be used by the PowerPC kexec_file_load
> implementation to find free memory for the purgatory stack.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h |  1 +
>  kernel/kexec_file.c   | 25 ++++++++++++++++++++-----
>  2 files changed, 21 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e16d845d587f..2b34e69db679 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -169,6 +169,7 @@ struct kexec_buf {
>  
>  int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  			       int (*func)(u64, u64, void *));
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf);
>  #endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b1f1f6402518..445d66add8ca 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -449,6 +449,23 @@ int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
>  		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
>  }
>  
> +/**
> + * kexec_locate_mem_hole - find free memory to load segment or use in purgatory

It is not necessary to use only for purgatory load..

> + * @kbuf:	Parameters for the memory search.
> + *
> + * On success, kbuf->mem will have the start address of the memory region found.
> + *
> + * Return: 0 on success, negative errno on error.
> + */
> +int kexec_locate_mem_hole(struct kexec_buf *kbuf)
> +{
> +	int ret;
> +
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> +
> +	return ret == 1 ? 0 : -EADDRNOTAVAIL;
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -493,11 +510,9 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
> -	if (ret != 1) {
> -		/* A suitable memory range could not be found for buffer */
> -		return -EADDRNOTAVAIL;
> -	}
> +	ret = kexec_locate_mem_hole(kbuf);
> +	if (ret)
> +		return ret;
>  
>  	/* Found a suitable memory range */
>  	ksegment = &image->segment[image->nr_segments];
> -- 
> 1.9.1
> 
> 

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 23 Juni 2016, 10:25:06 schrieb Dave Young:
> > On 06/22/16 at 08:30pm, Thiago Jung Bauermann wrote:
> > > Am Mittwoch, 22 Juni 2016, 18:20:47 schrieb Dave Young:
> > > > The patch looks good, but could the subject be more specific?
> > > > 
> > > > For example just like the first sentence of the patch descriotion:
> > > > Allow architectures to specify their own memory walking function
> > > 
> > > Ok, What about this? I also changed the description to refer to x86 arch
> > > instead of Intel arch.
> > 
> > It looks good to me.
> 
> This version has the struct kexec_buf documentation comments that were
> in patch 3/9. I fixed the names of the struct members, and changed their
> descriptions to try to be clearer.
> -- 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 
> 
> Subject: [PATCH 2/9] kexec_file: Allow arch-specific memory walking for
>  kexec_add_buffer
> 
> Allow architectures to specify a different memory walking function for
> kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
> PowerPC uses the memblock subsystem.
> 
> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
> Cc: Eric Biederman <ebiederm@xmission.com>
> Cc: Dave Young <dyoung@redhat.com>
> Cc: kexec@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
>  include/linux/kexec.h   | 25 ++++++++++++++++++++++++-
>  kernel/kexec_file.c     | 30 ++++++++++++++++++++++--------
>  kernel/kexec_internal.h | 14 --------------
>  3 files changed, 46 insertions(+), 23 deletions(-)
> 
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index e8acb2b43dd9..e16d845d587f 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -146,7 +146,30 @@ struct kexec_file_ops {
>  	kexec_verify_sig_t *verify_sig;
>  #endif
>  };
> -#endif
> +
> +/**
> + * struct kexec_buf - parameters for finding a place for a buffer in memory
> + * @image:	kexec image in which memory to search.
> + * @mem:	On return will have address of the buffer in memory.
> + * @memsz:	Size for the buffer in memory.
> + * @buf_align:	Minimum alignment needed.
> + * @buf_min:	The buffer can't be placed below this address.
> + * @buf_max:	The buffer can't be placed above this address.
> + * @top_down:	Allocate from top of memory.
> + */
> +struct kexec_buf {
> +	struct kimage *image;
> +	unsigned long mem;
> +	unsigned long memsz;
> +	unsigned long buf_align;
> +	unsigned long buf_min;
> +	unsigned long buf_max;
> +	bool top_down;
> +};

Rethink about the first patch, you dropped the user buffer in kexec_buf
But later your passing IMA digests buffer patchset may need use it.

So keep it in kexec_buf should be better.

For the IMA buffer patchset I'm still reading and learning the
background, will reply them later.

> +
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *));
> +#endif /* CONFIG_KEXEC_FILE */
>  
>  struct kimage {
>  	kimage_entry_t head;
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index b6eec7527e9f..b1f1f6402518 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
>  	return locate_mem_hole_bottom_up(start, end, kbuf);
>  }
>  
> +/**
> + * arch_kexec_walk_mem - call func(data) on free memory regions
> + * @kbuf:	Context info for the search. Also passed to @func.
> + * @func:	Function to call for each memory region.
> + *
> + * Return: The memory walk will stop when func returns a non-zero value
> + * and that value will be returned. If all free regions are visited without
> + * func returning non-zero, then zero will be returned.
> + */
> +int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
> +			       int (*func)(u64, u64, void *))
> +{
> +	if (kbuf->image->type == KEXEC_TYPE_CRASH)
> +		return walk_iomem_res_desc(crashk_res.desc,
> +					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> +					   crashk_res.start, crashk_res.end,
> +					   kbuf, func);
> +	else
> +		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
> +}
> +
>  /*
>   * Helper function for placing a buffer in a kexec segment. This assumes
>   * that kexec_mutex is held.
> @@ -472,14 +493,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
>  	kbuf->top_down = top_down;
>  
>  	/* Walk the RAM ranges and allocate a suitable range for the buffer */
> -	if (image->type == KEXEC_TYPE_CRASH)
> -		ret = walk_iomem_res_desc(crashk_res.desc,
> -				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
> -				crashk_res.start, crashk_res.end, kbuf,
> -				locate_mem_hole_callback);
> -	else
> -		ret = walk_system_ram_res(0, -1, kbuf,
> -					  locate_mem_hole_callback);
> +	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
>  	if (ret != 1) {
>  		/* A suitable memory range could not be found for buffer */
>  		return -EADDRNOTAVAIL;
> diff --git a/kernel/kexec_internal.h b/kernel/kexec_internal.h
> index eefd5bf960c2..4cef7e4706b0 100644
> --- a/kernel/kexec_internal.h
> +++ b/kernel/kexec_internal.h
> @@ -20,20 +20,6 @@ struct kexec_sha_region {
>  	unsigned long len;
>  };
>  
> -/*
> - * Keeps track of buffer parameters as provided by caller for requesting
> - * memory placement of buffer.
> - */
> -struct kexec_buf {
> -	struct kimage *image;
> -	unsigned long mem;
> -	unsigned long memsz;
> -	unsigned long buf_align;
> -	unsigned long buf_min;
> -	unsigned long buf_max;
> -	bool top_down;		/* allocate from top of memory hole */
> -};
> -
>  void kimage_file_post_load_cleanup(struct kimage *image);
>  #else /* CONFIG_KEXEC_FILE */
>  static inline void kimage_file_post_load_cleanup(struct kimage *image) { }
> -- 
> 1.9.1
> 
> 

Thanks
Dave

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Mittwoch, 29 Juni 2016, 15:45:18 schrieb Dave Young:
> On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> > > On 06/27/16 at 04:21pm, Dave Young wrote:
> > > Using one argument for both sounds more reasonable than using a
> > > separate
> > > argument for memory walk..
> > 
> > I agree. This patch doesn't use a separate top_down argument, it's the
> > same patch I sent earlier except that the comments to struct kexec_buf
> > are in patch 2/9. What do you think?
> 
> It looks good except one nitpick inline..
> 
>
> > +/**
> > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > purgatory
 
> It is not necessary to use only for purgatory load..

Ok, what about this?

/**
 * kexec_locate_mem_hole - find free memory in a given kimage.


[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Mittwoch, 29 Juni 2016, 15:47:51 schrieb Dave Young:
> On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > index e8acb2b43dd9..e16d845d587f 100644
> > --- a/include/linux/kexec.h
> > +++ b/include/linux/kexec.h
> > @@ -146,7 +146,30 @@ struct kexec_file_ops {
> > 
> >       kexec_verify_sig_t *verify_sig;
> >  
> >  #endif
> >  };
> > 
> > -#endif
> > +
> > +/**
> > + * struct kexec_buf - parameters for finding a place for a buffer in
> > memory + * @image:   kexec image in which memory to search.
> > + * @mem:     On return will have address of the buffer in memory.
> > + * @memsz:   Size for the buffer in memory.
> > + * @buf_align:       Minimum alignment needed.
> > + * @buf_min: The buffer can't be placed below this address.
> > + * @buf_max: The buffer can't be placed above this address.
> > + * @top_down:        Allocate from top of memory.
> > + */
> > +struct kexec_buf {
> > +     struct kimage *image;
> > +     unsigned long mem;
> > +     unsigned long memsz;
> > +     unsigned long buf_align;
> > +     unsigned long buf_min;
> > +     unsigned long buf_max;
> > +     bool top_down;
> > +};
> 
> Rethink about the first patch, you dropped the user buffer in kexec_buf
> But later your passing IMA digests buffer patchset may need use it.
> 
> So keep it in kexec_buf should be better.

I'm not following. The IMA buffer patchset doesn't use kexec_locate_mem_hole 
nor struct kexec_buf.

> For the IMA buffer patchset I'm still reading and learning the
> background, will reply them later.

Thank you!

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 06/29/16 at 06:18pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 29 Juni 2016, 15:47:51 schrieb Dave Young:
> > On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > > index e8acb2b43dd9..e16d845d587f 100644
> > > --- a/include/linux/kexec.h
> > > +++ b/include/linux/kexec.h
> > > @@ -146,7 +146,30 @@ struct kexec_file_ops {
> > > 
> > >       kexec_verify_sig_t *verify_sig;
> > >  
> > >  #endif
> > >  };
> > > 
> > > -#endif
> > > +
> > > +/**
> > > + * struct kexec_buf - parameters for finding a place for a buffer in
> > > memory + * @image:   kexec image in which memory to search.
> > > + * @mem:     On return will have address of the buffer in memory.
> > > + * @memsz:   Size for the buffer in memory.
> > > + * @buf_align:       Minimum alignment needed.
> > > + * @buf_min: The buffer can't be placed below this address.
> > > + * @buf_max: The buffer can't be placed above this address.
> > > + * @top_down:        Allocate from top of memory.
> > > + */
> > > +struct kexec_buf {
> > > +     struct kimage *image;
> > > +     unsigned long mem;
> > > +     unsigned long memsz;
> > > +     unsigned long buf_align;
> > > +     unsigned long buf_min;
> > > +     unsigned long buf_max;
> > > +     bool top_down;
> > > +};
> > 
> > Rethink about the first patch, you dropped the user buffer in kexec_buf
> > But later your passing IMA digests buffer patchset may need use it.
> > 
> > So keep it in kexec_buf should be better.
> 
> I'm not following. The IMA buffer patchset doesn't use kexec_locate_mem_hole 
> nor struct kexec_buf.

It does not use kexec_locate_mem_hole, but the buffer being passed is
very similar to a kexec_buf struct, no? 

So you may refactor kexec_add_buffer and your new function to pass only kimage
and a kbuf, it will be better than passing all those arguments separately.

> 
> > For the IMA buffer patchset I'm still reading and learning the
> > background, will reply them later.
> 
> Thank you!
> 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
> 

Thanks
Dave

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/29/16 at 06:09pm, Thiago Jung Bauermann wrote:
> Am Mittwoch, 29 Juni 2016, 15:45:18 schrieb Dave Young:
> > On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > > Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> > > > On 06/27/16 at 04:21pm, Dave Young wrote:
> > > > Using one argument for both sounds more reasonable than using a
> > > > separate
> > > > argument for memory walk..
> > > 
> > > I agree. This patch doesn't use a separate top_down argument, it's the
> > > same patch I sent earlier except that the comments to struct kexec_buf
> > > are in patch 2/9. What do you think?
> > 
> > It looks good except one nitpick inline..
> > 
> >
> > > +/**
> > > + * kexec_locate_mem_hole - find free memory to load segment or use in
> > > purgatory
>  
> > It is not necessary to use only for purgatory load..
> 
> Ok, what about this?
> 
> /**
>  * kexec_locate_mem_hole - find free memory in a given kimage.

Hmm, a given kimage sounds not correct, I can not get a better way to
describe it. How about below with a little change to your previous one:

kexec_locate_mem_hole - find a free chunk of memory to load kexec segment.
In powerpc the memory chunk can also be used for the purgatory stack.

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 30 Juni 2016, 11:07:00 schrieb Dave Young:
> On 06/29/16 at 06:18pm, Thiago Jung Bauermann wrote:
> > Am Mittwoch, 29 Juni 2016, 15:47:51 schrieb Dave Young:
> > > On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > > > +/**
> > > > + * struct kexec_buf - parameters for finding a place for a buffer
> > > > in
> > > > memory + * @image:   kexec image in which memory to search.
> > > > + * @mem:     On return will have address of the buffer in memory.
> > > > + * @memsz:   Size for the buffer in memory.
> > > > + * @buf_align:       Minimum alignment needed.
> > > > + * @buf_min: The buffer can't be placed below this address.
> > > > + * @buf_max: The buffer can't be placed above this address.
> > > > + * @top_down:        Allocate from top of memory.
> > > > + */
> > > > +struct kexec_buf {
> > > > +     struct kimage *image;
> > > > +     unsigned long mem;
> > > > +     unsigned long memsz;
> > > > +     unsigned long buf_align;
> > > > +     unsigned long buf_min;
> > > > +     unsigned long buf_max;
> > > > +     bool top_down;
> > > > +};
> > > 
> > > Rethink about the first patch, you dropped the user buffer in
> > > kexec_buf
> > > But later your passing IMA digests buffer patchset may need use it.
> > > 
> > > So keep it in kexec_buf should be better.
> > 
> > I'm not following. The IMA buffer patchset doesn't use
> > kexec_locate_mem_hole nor struct kexec_buf.
> 
> It does not use kexec_locate_mem_hole, but the buffer being passed is
> very similar to a kexec_buf struct, no?

If what you're saying is that the arguments passed to 
kexec_add_handover_buffer in the IMA buffer patchset are very similar to the 
arguments passed to kexec_add_buffer then yes, it's true.

> So you may refactor kexec_add_buffer and your new function to pass only
> kimage and a kbuf, it will be better than passing all those arguments
> separately.

To be honest I think struct kexec_buf is an implementation detail inside 
kexec_locate_mem_hole, made necessary because the callback functions it uses 
need to access its arguments. Callers of kexec_locate_mem_hole, 
kexec_add_handover_buffer and kexec_add_buffer shouldn't need to know it 
exists.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 30 Juni 2016, 11:41:19 schrieb Dave Young:
> On 06/29/16 at 06:09pm, Thiago Jung Bauermann wrote:
> > Am Mittwoch, 29 Juni 2016, 15:45:18 schrieb Dave Young:
> > > On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > > > Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> > > > > On 06/27/16 at 04:21pm, Dave Young wrote:
> > > It looks good except one nitpick inline..
> > > 
> > > > +/**
> > > > + * kexec_locate_mem_hole - find free memory to load segment or use
> > > > in
> > > > purgatory
> > > 
> > > It is not necessary to use only for purgatory load..
> > 
> > Ok, what about this?
> > 
> > /**
> > 
> >  * kexec_locate_mem_hole - find free memory in a given kimage.
> 
> Hmm, a given kimage sounds not correct, I can not get a better way to
> describe it. How about below with a little change to your previous one:
> 
> kexec_locate_mem_hole - find a free chunk of memory to load kexec segment.
> In powerpc the memory chunk can also be used for the purgatory stack.

That describes what the memory currently is used for. If powerpc or any 
other architecture starts to use the memory for something else, this comment 
would need to be updated. :-)

What the function really does is find free memory in the physical address 
space after the currently running kernel hands over control to whatever runs 
next. What that memory is used for is decided by the caller of the function.

Since (at least for now), the only things that run next are the purgatory 
and the next kernel, what about this?

kexec_locate_mem_hole - find free memory for the purgatory or the next 
kernel

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> Am Donnerstag, 30 Juni 2016, 11:07:00 schrieb Dave Young:
> > On 06/29/16 at 06:18pm, Thiago Jung Bauermann wrote:
> > > I'm not following. The IMA buffer patchset doesn't use
> > > kexec_locate_mem_hole nor struct kexec_buf.
> > 
> > It does not use kexec_locate_mem_hole, but the buffer being passed is
> > very similar to a kexec_buf struct, no?
> 
> If what you're saying is that the arguments passed to
> kexec_add_handover_buffer in the IMA buffer patchset are very similar to
> the arguments passed to kexec_add_buffer then yes, it's true.
> 
> > So you may refactor kexec_add_buffer and your new function to pass only
> > kimage and a kbuf, it will be better than passing all those arguments
> > separately.
> 
> To be honest I think struct kexec_buf is an implementation detail inside
> kexec_locate_mem_hole, made necessary because the callback functions it
> uses need to access its arguments. Callers of kexec_locate_mem_hole,
> kexec_add_handover_buffer and kexec_add_buffer shouldn't need to know it
> exists.

Elaborating a bit more: the argument list for these three functions are 
equal or similar because kexec_add_handover_buffer uses kexec_add_buffer, 
which uses kexec_locate_mem_hole.

It could be beneficial to have a struct to collect the arguments to these 
functions if someone using one of them would be likely to use another one 
with the same arguments. In that case, you set up kexec_buf once and then 
just pass it whenever you need to call one of those functions.

But that is unlikely to happen. A user of the kexec API will need to use 
only one of these functions with a given set of arguments, so they don't 
gain anything by setting up a struct.

Syntactically, I also don't think it's clearer to set struct members instead 
of simply passing arguments to a function, even if the argument list is 
long.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 3/9] kexec_file: Factor out kexec_locate_mem_hole from kexec_add_buffer.

[Dave Young]

On 06/30/16 at 01:08pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 30 Juni 2016, 11:41:19 schrieb Dave Young:
> > On 06/29/16 at 06:09pm, Thiago Jung Bauermann wrote:
> > > Am Mittwoch, 29 Juni 2016, 15:45:18 schrieb Dave Young:
> > > > On 06/28/16 at 07:18pm, Thiago Jung Bauermann wrote:
> > > > > Am Dienstag, 28 Juni 2016, 15:20:55 schrieb Dave Young:
> > > > > > On 06/27/16 at 04:21pm, Dave Young wrote:
> > > > It looks good except one nitpick inline..
> > > > 
> > > > > +/**
> > > > > + * kexec_locate_mem_hole - find free memory to load segment or use
> > > > > in
> > > > > purgatory
> > > > 
> > > > It is not necessary to use only for purgatory load..
> > > 
> > > Ok, what about this?
> > > 
> > > /**
> > > 
> > >  * kexec_locate_mem_hole - find free memory in a given kimage.
> > 
> > Hmm, a given kimage sounds not correct, I can not get a better way to
> > describe it. How about below with a little change to your previous one:
> > 
> > kexec_locate_mem_hole - find a free chunk of memory to load kexec segment.
> > In powerpc the memory chunk can also be used for the purgatory stack.
> 
> That describes what the memory currently is used for. If powerpc or any 
> other architecture starts to use the memory for something else, this comment 
> would need to be updated. :-)
> 
> What the function really does is find free memory in the physical address 
> space after the currently running kernel hands over control to whatever runs 
> next. What that memory is used for is decided by the caller of the function.
> 
> Since (at least for now), the only things that run next are the purgatory 
> and the next kernel, what about this?
> 
> kexec_locate_mem_hole - find free memory for the purgatory or the next 
> kernel

Ok, I'm fine with above version.

Thanks
Dave 

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > Am Donnerstag, 30 Juni 2016, 11:07:00 schrieb Dave Young:
> > > On 06/29/16 at 06:18pm, Thiago Jung Bauermann wrote:
> > > > I'm not following. The IMA buffer patchset doesn't use
> > > > kexec_locate_mem_hole nor struct kexec_buf.
> > > 
> > > It does not use kexec_locate_mem_hole, but the buffer being passed is
> > > very similar to a kexec_buf struct, no?
> > 
> > If what you're saying is that the arguments passed to
> > kexec_add_handover_buffer in the IMA buffer patchset are very similar to
> > the arguments passed to kexec_add_buffer then yes, it's true.
> > 
> > > So you may refactor kexec_add_buffer and your new function to pass only
> > > kimage and a kbuf, it will be better than passing all those arguments
> > > separately.
> > 
> > To be honest I think struct kexec_buf is an implementation detail inside
> > kexec_locate_mem_hole, made necessary because the callback functions it
> > uses need to access its arguments. Callers of kexec_locate_mem_hole,
> > kexec_add_handover_buffer and kexec_add_buffer shouldn't need to know it
> > exists.
> 
> Elaborating a bit more: the argument list for these three functions are 
> equal or similar because kexec_add_handover_buffer uses kexec_add_buffer, 
> which uses kexec_locate_mem_hole.
> 
> It could be beneficial to have a struct to collect the arguments to these 
> functions if someone using one of them would be likely to use another one 
> with the same arguments. In that case, you set up kexec_buf once and then 
> just pass it whenever you need to call one of those functions.
> 
> But that is unlikely to happen. A user of the kexec API will need to use 
> only one of these functions with a given set of arguments, so they don't 
> gain anything by setting up a struct.
> 
> Syntactically, I also don't think it's clearer to set struct members instead 
> of simply passing arguments to a function, even if the argument list is 
> long.

Sorry, I'm not sure I get your points but the long argument list really looks ugly,
since you are introducing more callbacks I still think a cleanup is necessary.

kexec_buffer struct is pretty fine to be a abstract of all these buffers.

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > > To be honest I think struct kexec_buf is an implementation detail
> > > inside
> > > kexec_locate_mem_hole, made necessary because the callback functions
> > > it
> > > uses need to access its arguments. Callers of kexec_locate_mem_hole,
> > > kexec_add_handover_buffer and kexec_add_buffer shouldn't need to know
> > > it
> > > exists.
> > 
> > Elaborating a bit more: the argument list for these three functions are
> > equal or similar because kexec_add_handover_buffer uses
> > kexec_add_buffer,
> > which uses kexec_locate_mem_hole.
> > 
> > It could be beneficial to have a struct to collect the arguments to
> > these
> > functions if someone using one of them would be likely to use another
> > one
> > with the same arguments. In that case, you set up kexec_buf once and
> > then
> > just pass it whenever you need to call one of those functions.
> > 
> > But that is unlikely to happen. A user of the kexec API will need to use
> > only one of these functions with a given set of arguments, so they don't
> > gain anything by setting up a struct.
> > 
> > Syntactically, I also don't think it's clearer to set struct members
> > instead of simply passing arguments to a function, even if the argument
> > list is long.
> 
> Sorry, I'm not sure I get your points but the long argument list really
> looks ugly, since you are introducing more callbacks I still think a
> cleanup is necessary.
> 
> kexec_buffer struct is pretty fine to be a abstract of all these buffers.

What I understood from what you said is that making the following change
results in code that is easier to understand:

@@ -650,6 +639,7 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 	const Elf_Shdr *sechdrs_c;
 	Elf_Shdr *sechdrs = NULL;
 	void *purgatory_buf = NULL;
+	struct kexec_buf buf;
 
 	/*
 	 * sechdrs_c points to section headers in purgatory and are read
@@ -757,11 +747,19 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 		buf_align = bss_align;
 
 	/* Add buffer to segment list */
-	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
-				buf_align, min, max, top_down,
-				&pi->purgatory_load_addr);
+	memset(&buf, 0, sizeof(struct kexec_buf));
+	buf.image = image;
+	buf.buffer = purgatory_buf;
+	buf.bufsz = buf_sz,
+	buf.memsz = memsz;
+	buf.buf_align = buf_align;
+	buf.buf_min = min;
+	buf.buf_max = max;
+	buf.top_down = top_down;
+	ret = kexec_add_buffer(&buf);
 	if (ret)
 		goto out;
+	pi->purgatory_load_addr = buf.mem;
 
 	/* Load SHF_ALLOC sections */
 	buf_addr = purgatory_buf;

There are 9 calls to kexec_add_buffer in the kernel (including arch/x86,
arch/powerpc/ and kernel/), plus 1 to kexec_locate_mem_hole
and 1 to kexec_add_handover_buffer, so there would be 11 places in
the code settings up kexec_buf. My opinion is that this change doesn't
improve code readability.

Also, I think that kexec_buf abstracts something that, from the
perspective of the user of the kexec API, lives only for the duration
of a single call to either of kexec_add_buffer, kexec_locate_mem_hole,
or kexec_add_handover_buffer. Because of this, there's no need from the
perspective of the API user to initialize this "object", so this just
adds to their cognitive load without any benefit to them.

I understand that this is all somewhat subjective, so if you still disagree
with my points I can provide a patch set implementing the change above.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 07/01/16 at 02:51pm, Thiago Jung Bauermann wrote:
> Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> > On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > > > To be honest I think struct kexec_buf is an implementation detail
> > > > inside
> > > > kexec_locate_mem_hole, made necessary because the callback functions
> > > > it
> > > > uses need to access its arguments. Callers of kexec_locate_mem_hole,
> > > > kexec_add_handover_buffer and kexec_add_buffer shouldn't need to know
> > > > it
> > > > exists.
> > > 
> > > Elaborating a bit more: the argument list for these three functions are
> > > equal or similar because kexec_add_handover_buffer uses
> > > kexec_add_buffer,
> > > which uses kexec_locate_mem_hole.
> > > 
> > > It could be beneficial to have a struct to collect the arguments to
> > > these
> > > functions if someone using one of them would be likely to use another
> > > one
> > > with the same arguments. In that case, you set up kexec_buf once and
> > > then
> > > just pass it whenever you need to call one of those functions.
> > > 
> > > But that is unlikely to happen. A user of the kexec API will need to use
> > > only one of these functions with a given set of arguments, so they don't
> > > gain anything by setting up a struct.
> > > 
> > > Syntactically, I also don't think it's clearer to set struct members
> > > instead of simply passing arguments to a function, even if the argument
> > > list is long.
> > 
> > Sorry, I'm not sure I get your points but the long argument list really
> > looks ugly, since you are introducing more callbacks I still think a
> > cleanup is necessary.
> > 
> > kexec_buffer struct is pretty fine to be a abstract of all these buffers.
> 
> What I understood from what you said is that making the following change
> results in code that is easier to understand:
> 
> @@ -650,6 +639,7 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  	const Elf_Shdr *sechdrs_c;
>  	Elf_Shdr *sechdrs = NULL;
>  	void *purgatory_buf = NULL;
> +	struct kexec_buf buf;
>  
>  	/*
>  	 * sechdrs_c points to section headers in purgatory and are read
> @@ -757,11 +747,19 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  		buf_align = bss_align;
>  
>  	/* Add buffer to segment list */
> -	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
> -				buf_align, min, max, top_down,
> -				&pi->purgatory_load_addr);
> +	memset(&buf, 0, sizeof(struct kexec_buf));
> +	buf.image = image;
> +	buf.buffer = purgatory_buf;
> +	buf.bufsz = buf_sz,
> +	buf.memsz = memsz;
> +	buf.buf_align = buf_align;
> +	buf.buf_min = min;
> +	buf.buf_max = max;
> +	buf.top_down = top_down;
> +	ret = kexec_add_buffer(&buf);
>  	if (ret)
>  		goto out;
> +	pi->purgatory_load_addr = buf.mem;
>  
>  	/* Load SHF_ALLOC sections */
>  	buf_addr = purgatory_buf;
> 
> There are 9 calls to kexec_add_buffer in the kernel (including arch/x86,
> arch/powerpc/ and kernel/), plus 1 to kexec_locate_mem_hole
> and 1 to kexec_add_handover_buffer, so there would be 11 places in
> the code settings up kexec_buf. My opinion is that this change doesn't
> improve code readability.

But the assignment can be moved to the beginning of the function
__kexec_load_purgatory, and avoid the local variables from the very
beginning. Just use kbuf.member instead.

> 
> Also, I think that kexec_buf abstracts something that, from the
> perspective of the user of the kexec API, lives only for the duration
> of a single call to either of kexec_add_buffer, kexec_locate_mem_hole,
> or kexec_add_handover_buffer. Because of this, there's no need from the
> perspective of the API user to initialize this "object", so this just
> adds to their cognitive load without any benefit to them.
> 
> I understand that this is all somewhat subjective, so if you still disagree
> with my points I can provide a patch set implementing the change above.

I still feel it should be changed if more callbacks being introduced,
though you can regard it is internal api, like above comment we do not
need to assign them seperately, the member values can be assigned
from the beginning.

Thanks
Dave

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Freitag, 01 Juli 2016, 14:36:02 schrieb Dave Young:
> On 07/01/16 at 02:51pm, Thiago Jung Bauermann wrote:
> > Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> > > On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > > > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > I understand that this is all somewhat subjective, so if you still
> > disagree with my points I can provide a patch set implementing the
> > change above.
> I still feel it should be changed if more callbacks being introduced,
> though you can regard it is internal api, like above comment we do not
> need to assign them seperately, the member values can be assigned
> from the beginning.

Ok, I'll implement the changes and submit a v4. Thanks for your review.

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Thiago Jung Bauermann]

Am Freitag, 01 Juli 2016, 17:02:23 schrieb Thiago Jung Bauermann:
> Am Freitag, 01 Juli 2016, 14:36:02 schrieb Dave Young:
> > On 07/01/16 at 02:51pm, Thiago Jung Bauermann wrote:
> > > Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> > > > On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > > > > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > > I understand that this is all somewhat subjective, so if you still
> > > disagree with my points I can provide a patch set implementing the
> > > change above.
> > 
> > I still feel it should be changed if more callbacks being introduced,
> > though you can regard it is internal api, like above comment we do not
> > need to assign them seperately, the member values can be assigned
> > from the beginning.
> 
> Ok, I'll implement the changes and submit a v4. Thanks for your review.

Sorry for creating more email traffic, but it'll be better if I ask this 
before I change all other places in the code. Is the code below what you
have in mind?

In particular, this version doesn't do the memset(&buf, 0, sizeof(buf))
that the previous code I sent earlier did. Is that ok?

@@ -643,13 +632,14 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 				  unsigned long max, int top_down)
 {
 	struct purgatory_info *pi = &image->purgatory_info;
-	unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
-	unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
+	unsigned long align, bss_align, bss_sz, bss_pad;
+	unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
 	unsigned char *buf_addr, *src;
 	int i, ret = 0, entry_sidx = -1;
 	const Elf_Shdr *sechdrs_c;
 	Elf_Shdr *sechdrs = NULL;
-	void *purgatory_buf = NULL;
+	struct kexec_buf buf = { .image = image, .buf_min = min,
+				.buf_max = max, .top_down = top_down };
 
 	/*
 	 * sechdrs_c points to section headers in purgatory and are read
@@ -715,9 +705,9 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 	}
 
 	/* Determine how much memory is needed to load relocatable object. */
-	buf_align = 1;
+	buf.buf_align = 1;
 	bss_align = 1;
-	buf_sz = 0;
+	buf.bufsz = 0;
 	bss_sz = 0;
 
 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
@@ -726,10 +716,10 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 
 		align = sechdrs[i].sh_addralign;
 		if (sechdrs[i].sh_type != SHT_NOBITS) {
-			if (buf_align < align)
-				buf_align = align;
-			buf_sz = ALIGN(buf_sz, align);
-			buf_sz += sechdrs[i].sh_size;
+			if (buf.buf_align < align)
+				buf.buf_align = align;
+			buf.bufsz = ALIGN(buf.bufsz, align);
+			buf.bufsz += sechdrs[i].sh_size;
 		} else {
 			/* bss section */
 			if (bss_align < align)
@@ -741,32 +731,31 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 
 	/* Determine the bss padding required to align bss properly */
 	bss_pad = 0;
-	if (buf_sz & (bss_align - 1))
-		bss_pad = bss_align - (buf_sz & (bss_align - 1));
+	if (buf.bufsz & (bss_align - 1))
+		bss_pad = bss_align - (buf.bufsz & (bss_align - 1));
 
-	memsz = buf_sz + bss_pad + bss_sz;
+	buf.memsz = buf.bufsz + bss_pad + bss_sz;
 
 	/* Allocate buffer for purgatory */
-	purgatory_buf = vzalloc(buf_sz);
-	if (!purgatory_buf) {
+	buf.buffer = vzalloc(buf.bufsz);
+	if (!buf.buffer) {
 		ret = -ENOMEM;
 		goto out;
 	}
 
-	if (buf_align < bss_align)
-		buf_align = bss_align;
+	if (buf.buf_align < bss_align)
+		buf.buf_align = bss_align;
 
 	/* Add buffer to segment list */
-	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
-				buf_align, min, max, top_down,
-				&pi->purgatory_load_addr);
+	ret = kexec_add_buffer(&buf);
 	if (ret)
 		goto out;
+	pi->purgatory_load_addr = buf.mem;
 
 	/* Load SHF_ALLOC sections */
-	buf_addr = purgatory_buf;
+	buf_addr = buf.buffer;
 	load_addr = curr_load_addr = pi->purgatory_load_addr;
-	bss_addr = load_addr + buf_sz + bss_pad;
+	bss_addr = load_addr + buf.bufsz + bss_pad;
 
 	for (i = 0; i < pi->ehdr->e_shnum; i++) {
 		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@@ -812,11 +801,11 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
 	 * Used later to identify which section is purgatory and skip it
 	 * from checksumming.
 	 */
-	pi->purgatory_buf = purgatory_buf;
+	pi->purgatory_buf = buf.buffer;
 	return ret;
 out:
 	vfree(sechdrs);
-	vfree(purgatory_buf);
+	vfree(buf.buffer);
 	return ret;
 }
 

[]'s
Thiago Jung Bauermann
IBM Linux Technology Center

Re: [PATCH v3 2/9] kexec_file: Generalize kexec_add_buffer.

[Dave Young]

On 07/01/16 at 05:31pm, Thiago Jung Bauermann wrote:
> Am Freitag, 01 Juli 2016, 17:02:23 schrieb Thiago Jung Bauermann:
> > Am Freitag, 01 Juli 2016, 14:36:02 schrieb Dave Young:
> > > On 07/01/16 at 02:51pm, Thiago Jung Bauermann wrote:
> > > > Am Donnerstag, 30 Juni 2016, 17:43:57 schrieb Dave Young:
> > > > > On 06/30/16 at 01:42pm, Thiago Jung Bauermann wrote:
> > > > > > Am Donnerstag, 30 Juni 2016, 12:49:44 schrieb Thiago Jung Bauermann:
> > > > I understand that this is all somewhat subjective, so if you still
> > > > disagree with my points I can provide a patch set implementing the
> > > > change above.
> > > 
> > > I still feel it should be changed if more callbacks being introduced,
> > > though you can regard it is internal api, like above comment we do not
> > > need to assign them seperately, the member values can be assigned
> > > from the beginning.
> > 
> > Ok, I'll implement the changes and submit a v4. Thanks for your review.
> 
> Sorry for creating more email traffic, but it'll be better if I ask this 
> before I change all other places in the code. Is the code below what you
> have in mind?

Thanks for the update, almost except a nitpick :)

> 
> In particular, this version doesn't do the memset(&buf, 0, sizeof(buf))
> that the previous code I sent earlier did. Is that ok?
> 
> @@ -643,13 +632,14 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  				  unsigned long max, int top_down)
>  {
>  	struct purgatory_info *pi = &image->purgatory_info;
> -	unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
> -	unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
> +	unsigned long align, bss_align, bss_sz, bss_pad;
> +	unsigned long entry, load_addr, curr_load_addr, bss_addr, offset;
>  	unsigned char *buf_addr, *src;
>  	int i, ret = 0, entry_sidx = -1;
>  	const Elf_Shdr *sechdrs_c;
>  	Elf_Shdr *sechdrs = NULL;
> -	void *purgatory_buf = NULL;
> +	struct kexec_buf buf = { .image = image, .buf_min = min,
> +				.buf_max = max, .top_down = top_down };
>  
>  	/*
>  	 * sechdrs_c points to section headers in purgatory and are read
> @@ -715,9 +705,9 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  	}
>  
>  	/* Determine how much memory is needed to load relocatable object. */
> -	buf_align = 1;
> +	buf.buf_align = 1;
>  	bss_align = 1;
> -	buf_sz = 0;
> +	buf.bufsz = 0;
>  	bss_sz = 0;

Above chunk can go to the initializatioin of struct kexec buf ealier.

>  
>  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
> @@ -726,10 +716,10 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  
>  		align = sechdrs[i].sh_addralign;
>  		if (sechdrs[i].sh_type != SHT_NOBITS) {
> -			if (buf_align < align)
> -				buf_align = align;
> -			buf_sz = ALIGN(buf_sz, align);
> -			buf_sz += sechdrs[i].sh_size;
> +			if (buf.buf_align < align)
> +				buf.buf_align = align;
> +			buf.bufsz = ALIGN(buf.bufsz, align);
> +			buf.bufsz += sechdrs[i].sh_size;
>  		} else {
>  			/* bss section */
>  			if (bss_align < align)
> @@ -741,32 +731,31 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  
>  	/* Determine the bss padding required to align bss properly */
>  	bss_pad = 0;
> -	if (buf_sz & (bss_align - 1))
> -		bss_pad = bss_align - (buf_sz & (bss_align - 1));
> +	if (buf.bufsz & (bss_align - 1))
> +		bss_pad = bss_align - (buf.bufsz & (bss_align - 1));
>  
> -	memsz = buf_sz + bss_pad + bss_sz;
> +	buf.memsz = buf.bufsz + bss_pad + bss_sz;
>  
>  	/* Allocate buffer for purgatory */
> -	purgatory_buf = vzalloc(buf_sz);
> -	if (!purgatory_buf) {
> +	buf.buffer = vzalloc(buf.bufsz);
> +	if (!buf.buffer) {
>  		ret = -ENOMEM;
>  		goto out;
>  	}
>  
> -	if (buf_align < bss_align)
> -		buf_align = bss_align;
> +	if (buf.buf_align < bss_align)
> +		buf.buf_align = bss_align;
>  
>  	/* Add buffer to segment list */
> -	ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
> -				buf_align, min, max, top_down,
> -				&pi->purgatory_load_addr);
> +	ret = kexec_add_buffer(&buf);
>  	if (ret)
>  		goto out;
> +	pi->purgatory_load_addr = buf.mem;
>  
>  	/* Load SHF_ALLOC sections */
> -	buf_addr = purgatory_buf;
> +	buf_addr = buf.buffer;
>  	load_addr = curr_load_addr = pi->purgatory_load_addr;
> -	bss_addr = load_addr + buf_sz + bss_pad;
> +	bss_addr = load_addr + buf.bufsz + bss_pad;
>  
>  	for (i = 0; i < pi->ehdr->e_shnum; i++) {
>  		if (!(sechdrs[i].sh_flags & SHF_ALLOC))
> @@ -812,11 +801,11 @@ static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
>  	 * Used later to identify which section is purgatory and skip it
>  	 * from checksumming.
>  	 */
> -	pi->purgatory_buf = purgatory_buf;
> +	pi->purgatory_buf = buf.buffer;
>  	return ret;
>  out:
>  	vfree(sechdrs);
> -	vfree(purgatory_buf);
> +	vfree(buf.buffer);
>  	return ret;
>  }
>  
> 
> []'s
> Thiago Jung Bauermann
> IBM Linux Technology Center
>