[PATCH v6 18/21] arm64:ilp32: add vdso-ilp32 and use for signal return

[Yury Norov <ynorov@caviumnetworks.com>]

From: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

ILP32 VDSO exports next symbols:
 __kernel_rt_sigreturn;
 __kernel_gettimeofday;
 __kernel_clock_gettime;
 __kernel_clock_getres;

What shared object to use, kernel selects depending on result of
is_ilp32_compat_task() in arch/arm64/kernel/vdso.c, so it substitutes
correct pages and spec.

Adjusted to move the move data page before code pages in sync with
commit 601255ae3c98fdeeee3a8bb4696425e4f868b4f1

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
---
 arch/arm64/include/asm/vdso.h                 |  6 ++
 arch/arm64/kernel/Makefile                    |  5 ++
 arch/arm64/kernel/signal.c                    |  2 +
 arch/arm64/kernel/vdso-ilp32/.gitignore       |  2 +
 arch/arm64/kernel/vdso-ilp32/Makefile         | 72 ++++++++++++++++++++
 arch/arm64/kernel/vdso-ilp32/vdso-ilp32.S     | 33 ++++++++++
 arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S | 95 +++++++++++++++++++++++++++
 arch/arm64/kernel/vdso.c                      | 61 ++++++++++++++---
 8 files changed, 266 insertions(+), 10 deletions(-)
 create mode 100644 arch/arm64/kernel/vdso-ilp32/.gitignore
 create mode 100644 arch/arm64/kernel/vdso-ilp32/Makefile
 create mode 100644 arch/arm64/kernel/vdso-ilp32/vdso-ilp32.S
 create mode 100644 arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S

diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h
index 839ce00..649a9a4 100644
--- a/arch/arm64/include/asm/vdso.h
+++ b/arch/arm64/include/asm/vdso.h
@@ -29,6 +29,12 @@
 
 #include <generated/vdso-offsets.h>
 
+#ifdef CONFIG_ARM64_ILP32
+#include <generated/vdso-ilp32-offsets.h>
+#else
+#define vdso_offset_sigtramp_ilp32
+#endif
+
 #define VDSO_SYMBOL(base, name)						   \
 ({									   \
 	(void *)(vdso_offset_##name - VDSO_LBASE + (unsigned long)(base)); \
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index c846626..19d7e17 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -46,6 +46,7 @@ arm64-obj-$(CONFIG_ARMV8_DEPRECATED)	+= armv8_deprecated.o
 arm64-obj-$(CONFIG_ACPI)		+= acpi.o
 
 obj-y					+= $(arm64-obj-y) vdso/
+obj-$(CONFIG_ARM64_ILP32)		+= vdso-ilp32/
 obj-m					+= $(arm64-obj-m)
 head-y					:= head.o
 extra-y					+= $(head-y) vmlinux.lds
@@ -53,3 +54,7 @@ extra-y					+= $(head-y) vmlinux.lds
 # vDSO - this must be built first to generate the symbol offsets
 $(call objectify,$(arm64-obj-y)): $(obj)/vdso/vdso-offsets.h
 $(obj)/vdso/vdso-offsets.h: $(obj)/vdso
+
+# vDSO - this must be built first to generate the symbol offsets
+$(call objectify,$(arm64-obj-y)): $(obj)/vdso-ilp32/vdso-ilp32-offsets.h
+$(obj)/vdso-ilp32/vdso-ilp32-offsets.h: $(obj)/vdso-ilp32
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index f8d4c92..0648aa5 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -241,6 +241,8 @@ void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 
 	if (ka->sa.sa_flags & SA_RESTORER)
 		sigtramp = ka->sa.sa_restorer;
+	else if (is_ilp32_compat_task())
+		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp_ilp32);
 	else
 		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
 
diff --git a/arch/arm64/kernel/vdso-ilp32/.gitignore b/arch/arm64/kernel/vdso-ilp32/.gitignore
new file mode 100644
index 0000000..61806c3
--- /dev/null
+++ b/arch/arm64/kernel/vdso-ilp32/.gitignore
@@ -0,0 +1,2 @@
+vdso-ilp32.lds
+vdso-ilp32-offsets.h
diff --git a/arch/arm64/kernel/vdso-ilp32/Makefile b/arch/arm64/kernel/vdso-ilp32/Makefile
new file mode 100644
index 0000000..c8f5472
--- /dev/null
+++ b/arch/arm64/kernel/vdso-ilp32/Makefile
@@ -0,0 +1,72 @@
+#
+# Building a vDSO image for AArch64.
+#
+# Author: Will Deacon <will.deacon@arm.com>
+# Heavily based on the vDSO Makefiles for other archs.
+#
+
+obj-ilp32-vdso := gettimeofday-ilp32.o note-ilp32.o sigreturn-ilp32.o
+
+# Build rules
+targets := $(obj-ilp32-vdso) vdso-ilp32.so vdso-ilp32.so.dbg
+obj-ilp32-vdso := $(addprefix $(obj)/, $(obj-ilp32-vdso))
+
+ccflags-y := -shared -fno-common -fno-builtin
+ccflags-y += -nostdlib -Wl,-soname=linux-ilp32-vdso.so.1 \
+		$(call cc-ldoption, -Wl$(comma)--hash-style=sysv)
+
+obj-y += vdso-ilp32.o
+extra-y += vdso-ilp32.lds vdso-ilp32-offsets.h
+CPPFLAGS_vdso-ilp32.lds += -P -C -U$(ARCH) -mabi=ilp32
+
+# Force dependency (incbin is bad)
+$(obj)/vdso-ilp32.o : $(obj)/vdso-ilp32.so
+
+# Link rule for the .so file, .lds has to be first
+$(obj)/vdso-ilp32.so.dbg: $(src)/vdso-ilp32.lds $(obj-ilp32-vdso)
+	$(call if_changed,vdso-ilp32ld)
+
+# Strip rule for the .so file
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+	$(call if_changed,objcopy)
+
+# Generate VDSO offsets using helper script
+gen-vdsosym := $(srctree)/$(src)/../vdso/gen_vdso_offsets.sh
+quiet_cmd_vdsosym = VDSOSYM $@
+define cmd_vdsosym
+	$(NM) $< | $(gen-vdsosym) | LC_ALL=C sort > $@ && \
+	cp $@ include/generated/
+endef
+
+$(obj)/vdso-ilp32-offsets.h: $(obj)/vdso-ilp32.so.dbg FORCE
+	$(call if_changed,vdsosym)
+
+# Assembly rules for the .S files
+#$(obj-ilp32-vdso): %.o: $(src)/../vdso/$(subst -ilp32,,%.S)
+#	$(call if_changed_dep,vdso-ilp32as)
+
+$(obj)/gettimeofday-ilp32.o: $(src)/../vdso/gettimeofday.S
+	$(call if_changed_dep,vdso-ilp32as)
+
+$(obj)/note-ilp32.o: $(src)/../vdso/note.S
+	$(call if_changed_dep,vdso-ilp32as)
+
+$(obj)/sigreturn-ilp32.o: $(src)/../vdso/sigreturn.S
+	$(call if_changed_dep,vdso-ilp32as)
+
+# Actual build commands
+quiet_cmd_vdso-ilp32ld = VDSOILP32L $@
+      cmd_vdso-ilp32ld = $(CC) $(c_flags) -mabi=ilp32  -Wl,-n -Wl,-T $^ -o $@
+quiet_cmd_vdso-ilp32as = VDSOILP32A $@
+      cmd_vdso-ilp32as = $(CC) $(a_flags) -mabi=ilp32 -c -o $@ $<
+
+# Install commands for the unstripped file
+quiet_cmd_vdso_install = INSTALL $@
+      cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
+
+vdso-ilp32.so: $(obj)/vdso-ilp32.so.dbg
+	@mkdir -p $(MODLIB)/vdso
+	$(call cmd,vdso_install)
+
+vdso_install: vdso-ilp32.so
diff --git a/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.S b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.S
new file mode 100644
index 0000000..46ac072
--- /dev/null
+++ b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.S
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ */
+
+#include <linux/init.h>
+#include <linux/linkage.h>
+#include <linux/const.h>
+#include <asm/page.h>
+
+	__PAGE_ALIGNED_DATA
+
+	.globl vdso_ilp32_start, vdso_ilp32_end
+	.balign PAGE_SIZE
+vdso_ilp32_start:
+	.incbin "arch/arm64/kernel/vdso-ilp32/vdso-ilp32.so"
+	.balign PAGE_SIZE
+vdso_ilp32_end:
+
+	.previous
diff --git a/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S
new file mode 100644
index 0000000..ddc63fd
--- /dev/null
+++ b/arch/arm64/kernel/vdso-ilp32/vdso-ilp32.lds.S
@@ -0,0 +1,95 @@
+/*
+ * GNU linker script for the VDSO library.
+ *
+ * Copyright (C) 2012 ARM Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
+ * Heavily based on the vDSO linker scripts for other archs.
+ */
+
+#include <linux/const.h>
+#include <asm/page.h>
+#include <asm/vdso.h>
+
+SECTIONS
+{
+	PROVIDE(_vdso_data = . - PAGE_SIZE);
+	. = VDSO_LBASE + SIZEOF_HEADERS;
+
+	.hash		: { *(.hash) }			:text
+	.gnu.hash	: { *(.gnu.hash) }
+	.dynsym		: { *(.dynsym) }
+	.dynstr		: { *(.dynstr) }
+	.gnu.version	: { *(.gnu.version) }
+	.gnu.version_d	: { *(.gnu.version_d) }
+	.gnu.version_r	: { *(.gnu.version_r) }
+
+	.note		: { *(.note.*) }		:text	:note
+
+	. = ALIGN(16);
+
+	.text		: { *(.text*) }			:text	=0xd503201f
+	PROVIDE (__etext = .);
+	PROVIDE (_etext = .);
+	PROVIDE (etext = .);
+
+	.eh_frame_hdr	: { *(.eh_frame_hdr) }		:text	:eh_frame_hdr
+	.eh_frame	: { KEEP (*(.eh_frame)) }	:text
+
+	.dynamic	: { *(.dynamic) }		:text	:dynamic
+
+	.rodata		: { *(.rodata*) }		:text
+
+	_end = .;
+	PROVIDE(end = .);
+
+	/DISCARD/	: {
+		*(.note.GNU-stack)
+		*(.data .data.* .gnu.linkonce.d.* .sdata*)
+		*(.bss .sbss .dynbss .dynsbss)
+	}
+}
+
+/*
+ * We must supply the ELF program headers explicitly to get just one
+ * PT_LOAD segment, and set the flags explicitly to make segments read-only.
+ */
+PHDRS
+{
+	text		PT_LOAD		FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */
+	note		PT_NOTE		FLAGS(4);		/* PF_R */
+	eh_frame_hdr	PT_GNU_EH_FRAME;
+}
+
+/*
+ * This controls what symbols we export from the DSO.
+ */
+VERSION
+{
+	LINUX_2.6 {
+	global:
+		__kernel_rt_sigreturn;
+		__kernel_gettimeofday;
+		__kernel_clock_gettime;
+		__kernel_clock_getres;
+	local: *;
+	};
+}
+
+/*
+ * Make the sigreturn code visible to the kernel.
+ */
+VDSO_sigtramp_ilp32		= __kernel_rt_sigreturn;
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 26352a6..521a8e4 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -40,6 +40,12 @@ extern char vdso_start, vdso_end;
 static unsigned long vdso_pages;
 static struct page **vdso_pagelist;
 
+#ifdef CONFIG_ARM64_ILP32
+extern char vdso_ilp32_start, vdso_ilp32_end;
+static unsigned long vdso_ilp32_pages;
+static struct page **vdso_ilp32_pagelist;
+#endif
+
 /*
  * The vDSO data page.
  */
@@ -109,24 +115,29 @@ int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
 }
 #endif /* CONFIG_AARCH32_EL0 */
 
-static struct vm_special_mapping vdso_spec[2];
-
-static int __init vdso_init(void)
+static int __init vdso_init_common(char *vdso_start, char *vdso_end,
+					  unsigned long *vdso_pagesp,
+					  struct page ***vdso_pagelistp,
+					  struct vm_special_mapping* vdso_spec)
 {
 	int i;
+	unsigned long vdso_pages;
+	struct page **vdso_pagelist;
 
-	if (memcmp(&vdso_start, "\177ELF", 4)) {
+	if (memcmp(vdso_start, "\177ELF", 4)) {
 		pr_err("vDSO is not a valid ELF object!\n");
 		return -EINVAL;
 	}
 
-	vdso_pages = (&vdso_end - &vdso_start) >> PAGE_SHIFT;
+	vdso_pages = (vdso_end - vdso_start) >> PAGE_SHIFT;
+	*vdso_pagesp = vdso_pages;
 	pr_info("vdso: %ld pages (%ld code @ %p, %ld data @ %p)\n",
-		vdso_pages + 1, vdso_pages, &vdso_start, 1L, vdso_data);
+		vdso_pages + 1, vdso_pages, vdso_start, 1L, vdso_data);
 
 	/* Allocate the vDSO pagelist, plus a page for the data. */
 	vdso_pagelist = kcalloc(vdso_pages + 1, sizeof(struct page *),
 				GFP_KERNEL);
+	*vdso_pagelistp = vdso_pagelist;
 	if (vdso_pagelist == NULL)
 		return -ENOMEM;
 
@@ -135,7 +146,7 @@ static int __init vdso_init(void)
 
 	/* Grab the vDSO code pages. */
 	for (i = 0; i < vdso_pages; i++)
-		vdso_pagelist[i + 1] = virt_to_page(&vdso_start + i * PAGE_SIZE);
+		vdso_pagelist[i + 1] = virt_to_page(vdso_start + i * PAGE_SIZE);
 
 	/* Populate the special mapping structures */
 	vdso_spec[0] = (struct vm_special_mapping) {
@@ -150,16 +161,46 @@ static int __init vdso_init(void)
 
 	return 0;
 }
+
+static struct vm_special_mapping vdso_spec[2];
+
+static int __init vdso_init(void)
+{
+	return vdso_init_common(&vdso_start, &vdso_end,
+				&vdso_pages, &vdso_pagelist,
+				vdso_spec);
+}
 arch_initcall(vdso_init);
 
+#ifdef CONFIG_ARM64_ILP32
+static struct vm_special_mapping vdso_ilp32_spec[2];
+
+static int __init vdso_ilp32_init(void)
+{
+	return vdso_init_common(&vdso_ilp32_start, &vdso_ilp32_end,
+				&vdso_ilp32_pages, &vdso_ilp32_pagelist,
+				vdso_ilp32_spec);
+}
+arch_initcall(vdso_ilp32_init);
+#endif
+
 int arch_setup_additional_pages(struct linux_binprm *bprm,
 				int uses_interp)
 {
 	struct mm_struct *mm = current->mm;
 	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
 	void *ret;
+	unsigned long pages = vdso_pages;
+	struct vm_special_mapping *spec = vdso_spec;
+
+#ifdef CONFIG_ARM64_ILP32
+	if (is_ilp32_compat_task()) {
+	        pages = vdso_ilp32_pages;
+	        spec = vdso_ilp32_spec;
+	}
+#endif
 
-	vdso_text_len = vdso_pages << PAGE_SHIFT;
+	vdso_text_len = pages << PAGE_SHIFT;
 	/* Be sure to map the data page */
 	vdso_mapping_len = vdso_text_len + PAGE_SIZE;
 
@@ -171,7 +212,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
 	}
 	ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE,
 				       VM_READ|VM_MAYREAD,
-				       &vdso_spec[0]);
+				       &spec[0]);
 	if (IS_ERR(ret))
 		goto up_fail;
 
@@ -180,7 +221,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm,
 	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
 				       VM_READ|VM_EXEC|
 				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
-				       &vdso_spec[1]);
+				       &spec[1]);
 	if (IS_ERR(ret))
 		goto up_fail;
 
-- 
2.5.0