Re: [PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

Re: [PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
In-Reply-To: <24d93c713f6faeaee6105f57c3d94ac17f12405f.1626266516.git.geert+renesas@glider.be>
References: <24d93c713f6faeaee6105f57c3d94ac17f12405f.1626266516.git.geert+renesas@glider.be>
TO: Geert Uytterhoeven <geert+renesas@glider.be>
TO: Rob Herring <robh+dt@kernel.org>
TO: Russell King <linux@armlinux.org.uk>
TO: Nicolas Pitre <nico@fluxnic.net>
TO: Ard Biesheuvel <ardb@kernel.org>
TO: Linus Walleij <linus.walleij@linaro.org>
TO: Catalin Marinas <catalin.marinas@arm.com>
TO: Will Deacon <will@kernel.org>
TO: Nick Kossifidis <mick@ics.forth.gr>
TO: Paul Walmsley <paul.walmsley@sifive.com>
TO: Palmer Dabbelt <palmer@dabbelt.com>

Hi Geert,

I love your patch! Perhaps something to improve:

[auto build test WARNING on robh/for-next]
[also build test WARNING on arm64/for-next/core arm/for-next linus/master v5.14-rc1 next-20210714]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Geert-Uytterhoeven/Add-generic-support-for-kdump-DT-properties/20210714-205223
base:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux.git for-next
:::::: branch date: 12 hours ago
:::::: commit date: 12 hours ago
config: x86_64-randconfig-b001-20210714 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8d69635ed9ecf36fd0ca85906bfde17949671cbe)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # apt-get install iwyu # include-what-you-use
        # https://github.com/0day-ci/linux/commit/3b97a030801ac122756ae95f428bf673ed5b3857
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Geert-Uytterhoeven/Add-generic-support-for-kdump-DT-properties/20210714-205223
        git checkout 3b97a030801ac122756ae95f428bf673ed5b3857
        # save the attached .config to linux build tree
        mkdir build_dir
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross C=1 CHECK=iwyu O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/of/

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


iwyu warnings: (new ones prefixed by >>)
   drivers/of/fdt.c:31:1: iwyu: warning: superfluous #include <asm/page.h>
   drivers/of/fdt.c:30:1: iwyu: warning: superfluous #include <asm/setup.h>
>> drivers/of/fdt.c:11:1: iwyu: warning: superfluous #include <linux/crash_dump.h>
   drivers/of/fdt.c:12:1: iwyu: warning: superfluous #include <linux/crc32.h>
   drivers/of/fdt.c:25:1: iwyu: warning: superfluous #include <linux/debugfs.h>
   drivers/of/fdt.c:22:1: iwyu: warning: superfluous #include <linux/errno.h>
   drivers/of/fdt.c:14:1: iwyu: warning: superfluous #include <linux/initrd.h>
   drivers/of/fdt.c:13:1: iwyu: warning: superfluous #include <linux/kernel.h>
   drivers/of/fdt.c:24:1: iwyu: warning: superfluous #include <linux/libfdt.h>
   drivers/of/fdt.c:15:1: iwyu: warning: superfluous #include <linux/memblock.h>
   drivers/of/fdt.c:19:1: iwyu: warning: superfluous #include <linux/of_reserved_mem.h>
   drivers/of/fdt.c:28:1: iwyu: warning: superfluous #include <linux/random.h>
   drivers/of/fdt.c:26:1: iwyu: warning: superfluous #include <linux/serial_core.h>
   drivers/of/fdt.c:20:1: iwyu: warning: superfluous #include <linux/sizes.h>
   drivers/of/fdt.c:27:1: iwyu: warning: superfluous #include <linux/sysfs.h>

vim +11 drivers/of/fdt.c

606ad42aa3b1fe Rob Herring          2016-06-15  10  
3b97a030801ac1 Geert Uytterhoeven   2021-07-14 @11  #include <linux/crash_dump.h>
08d53aa58cb162 Ard Biesheuvel       2014-11-14  12  #include <linux/crc32.h>
41f880091c15b0 Grant Likely         2009-11-23  13  #include <linux/kernel.h>
f7b3a8355ba6ca Grant Likely         2009-11-24  14  #include <linux/initrd.h>
a1727da599ad03 Grant Likely         2013-08-28  15  #include <linux/memblock.h>
f8062386671a59 Guenter Roeck        2015-12-05  16  #include <linux/mutex.h>
e169cfbef46d62 Grant Likely         2009-11-23  17  #include <linux/of.h>
e169cfbef46d62 Grant Likely         2009-11-23  18  #include <linux/of_fdt.h>
3f0c8206644836 Marek Szyprowski     2014-02-28  19  #include <linux/of_reserved_mem.h>
e8d9d1f5485b52 Marek Szyprowski     2014-02-28  20  #include <linux/sizes.h>
4ef7b373df330b Jeremy Kerr          2010-02-14  21  #include <linux/string.h>
4ef7b373df330b Jeremy Kerr          2010-02-14  22  #include <linux/errno.h>
fe14042358fac0 Stephen Neuendorffer 2010-11-18  23  #include <linux/slab.h>
e6a6928c3ea1d0 Rob Herring          2014-04-02  24  #include <linux/libfdt.h>
b0a6fb36a49f72 Rob Herring          2014-04-02  25  #include <linux/debugfs.h>
fb11ffe74c794a Rob Herring          2014-03-27  26  #include <linux/serial_core.h>
08d53aa58cb162 Ard Biesheuvel       2014-11-14  27  #include <linux/sysfs.h>
428826f5358c92 Hsin-Yi Wang         2019-08-23  28  #include <linux/random.h>
51975db0b7333c Grant Likely         2010-02-01  29  

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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[PATCH v4 00/10] Add generic support for kdump DT properties

[Geert Uytterhoeven]

	Hi all,

This patch series adds generic support for parsing DT properties related
to crash dump kernels ("linux,elfcorehdr" and "linux,elfcorehdr" under
the "/chosen" node), makes use of it on arm64, arm32, and (partially)
riscv, and performs a few cleanups.  It is an evolution of the
combination of [1] and [2].

The series consists of 5 parts:
  1. Patches 1-2 prepare (the visibility of) variables used to hold
     information retrieved from the DT properties.
  2. Patches 3-5 add support to the FDT core for parsing the properties.
     This can co-exist safely with architecture-specific parsing, until
     the latter has been removed.
  3. Patch 6 removes the non-standard handling of "linux,elfcorehdr" on
     riscv.
     I think this can be applied independently, as the non-standard
     handling is in v5.13, but upstream riscv kdump support is still
     incomplete.
  4. Patches 7-9 convert arm64 to use the generic handling instead of
     its own implementation.
  5. Patch 10 adds support for kdump properties to arm32.
     The corresponding patch for kexec-tools is "[PATCH] arm: kdump: Add
     DT properties to crash dump kernel's DTB"[3], which is still valid.

Changes compared to the previous versions:
  - Make elfcorehdr_{addr,size} always visible,
  - Add variables for usable memory limitation,
  - Use IS_ENABLED() instead of #ifdef (incl. initrd and arm64),
  - Clarify what architecture-specific code is still responsible for,
  - Add generic support for parsing linux,usable-memory-range,
  - Remove custom linux,usable-memory-range parsing on arm64,
  - Use generic handling on ARM.
  
This has been tested on arm32 and arm64, and compile-tested on riscv64.

Thanks for your comments!

[1] "[PATCH v3] ARM: Parse kdump DT properties"
    https://lore.kernel.org/r/20210317113130.2554368-1-geert+renesas@glider.be/
[2] "[PATCH 0/3] Add generic-support for linux,elfcorehdr and fix riscv"
    https://lore.kernel.org/r/cover.1623780059.git.geert+renesas@glider.be/
[3] "[PATCH] arm: kdump: Add DT properties to crash dump kernel's DTB"
    https://lore.kernel.org/linux-arm-kernel/20200902154129.6358-1-geert+renesas@glider.be/


Geert Uytterhoeven (10):
  crash_dump: Make elfcorehdr_{addr,size} always visible
  memblock: Add variables for usable memory limitation
  of: fdt: Add generic support for parsing elf core headers property
  of: fdt: Add generic support for parsing usable memory range property
  of: fdt: Use IS_ENABLED(CONFIG_BLK_DEV_INITRD) instead of #ifdef
  riscv: Remove non-standard linux,elfcorehdr handling
  arm64: kdump: Remove custom linux,elfcorehdr parsing
  arm64: kdump: Remove custom linux,usable-memory-range parsing
  arm64: kdump: Use IS_ENABLED(CONFIG_CRASH_DUMP) instead of #ifdef
  ARM: Parse kdump DT properties

 Documentation/devicetree/bindings/chosen.txt  | 12 ++--
 .../arm/boot/compressed/fdt_check_mem_start.c | 48 ++++++++++++--
 arch/arm/mm/init.c                            | 30 +++++++++
 arch/arm64/mm/init.c                          | 63 +------------------
 arch/riscv/mm/init.c                          | 20 ------
 drivers/of/fdt.c                              | 63 ++++++++++++++++---
 include/linux/crash_dump.h                    |  7 ++-
 include/linux/memblock.h                      |  6 ++
 mm/memblock.c                                 |  2 +
 9 files changed, 148 insertions(+), 103 deletions(-)

-- 
2.25.1

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds

[PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

[Geert Uytterhoeven]

There are two methods to specify the location of the elf core headers:
using the "elfcorehdr=" kernel parameter, as handled by generic code in
kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the
"/chosen" node in the Device Tree, as handled by architecture-specific
code in arch/arm64/mm/init.c.

Extend support for "linux,elfcorehdr" to all platforms supporting DT by
adding platform-agnostic handling for parsing this property to the FDT
core code.  This can co-exist safely with the architecture-specific
parsing, until the latter has been removed.

This requires moving the call to of_scan_flat_dt() up, as the code
scanning the "/chosen" node now needs to be aware of the values of
"#address-cells" and "#size-cells".

Architecture-specific code still has to reserve the memory used by the
elf core headers, if present.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
About the change to chosen.txt: I have a similar change for
schemas/chosen.yaml in dt-schema.

v4:
  - Use IS_ENABLED() instead of #ifdef,
  - Clarify what architecture-specific code is still responsible for.
---
 Documentation/devicetree/bindings/chosen.txt |  6 ++--
 drivers/of/fdt.c                             | 34 ++++++++++++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 45e79172a646c537..5b0b94eb2d04e79d 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -106,9 +106,9 @@ respectively, of the root node.
 linux,elfcorehdr
 ----------------
 
-This property (currently used only on arm64) holds the memory range,
-the address and the size, of the elf core header which mainly describes
-the panicked kernel's memory layout as PT_LOAD segments of elf format.
+This property holds the memory range, the address and the size, of the elf
+core header which mainly describes the panicked kernel's memory layout as
+PT_LOAD segments of elf format.
 e.g.
 
 / {
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 344f16bb04ccf081..f797d52c5b492cb7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt)	"OF: fdt: " fmt
 
+#include <linux/crash_dump.h>
 #include <linux/crc32.h>
 #include <linux/kernel.h>
 #include <linux/initrd.h>
@@ -908,6 +909,32 @@ static inline void early_init_dt_check_for_initrd(unsigned long node)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+/**
+ * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat
+ * tree
+ * @node: reference to node containing elfcorehdr location ('chosen')
+ */
+static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
+{
+	const __be32 *prop;
+	int len;
+
+	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
+		return;
+
+	pr_debug("Looking for elfcorehdr property... ");
+
+	prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+	if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
+		return;
+
+	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n",
+		 elfcorehdr_addr, elfcorehdr_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1055,6 +1082,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 		return 0;
 
 	early_init_dt_check_for_initrd(node);
+	early_init_dt_check_for_elfcorehdr(node);
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
@@ -1199,14 +1227,14 @@ void __init early_init_dt_scan_nodes(void)
 {
 	int rc = 0;
 
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
 	/* Retrieve various information from the /chosen node */
 	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
 	if (!rc)
 		pr_warn("No chosen node found, continuing without\n");
 
-	/* Initialize {size,address}-cells info */
-	of_scan_flat_dt(early_init_dt_scan_root, NULL);
-
 	/* Setup memory, calling early_init_dt_add_memory_arch */
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 }
-- 
2.25.1

[PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

[Geert Uytterhoeven]

There are two methods to specify the location of the elf core headers:
using the "elfcorehdr=" kernel parameter, as handled by generic code in
kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the
"/chosen" node in the Device Tree, as handled by architecture-specific
code in arch/arm64/mm/init.c.

Extend support for "linux,elfcorehdr" to all platforms supporting DT by
adding platform-agnostic handling for parsing this property to the FDT
core code.  This can co-exist safely with the architecture-specific
parsing, until the latter has been removed.

This requires moving the call to of_scan_flat_dt() up, as the code
scanning the "/chosen" node now needs to be aware of the values of
"#address-cells" and "#size-cells".

Architecture-specific code still has to reserve the memory used by the
elf core headers, if present.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
About the change to chosen.txt: I have a similar change for
schemas/chosen.yaml in dt-schema.

v4:
  - Use IS_ENABLED() instead of #ifdef,
  - Clarify what architecture-specific code is still responsible for.
---
 Documentation/devicetree/bindings/chosen.txt |  6 ++--
 drivers/of/fdt.c                             | 34 ++++++++++++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 45e79172a646c537..5b0b94eb2d04e79d 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -106,9 +106,9 @@ respectively, of the root node.
 linux,elfcorehdr
 ----------------
 
-This property (currently used only on arm64) holds the memory range,
-the address and the size, of the elf core header which mainly describes
-the panicked kernel's memory layout as PT_LOAD segments of elf format.
+This property holds the memory range, the address and the size, of the elf
+core header which mainly describes the panicked kernel's memory layout as
+PT_LOAD segments of elf format.
 e.g.
 
 / {
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 344f16bb04ccf081..f797d52c5b492cb7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt)	"OF: fdt: " fmt
 
+#include <linux/crash_dump.h>
 #include <linux/crc32.h>
 #include <linux/kernel.h>
 #include <linux/initrd.h>
@@ -908,6 +909,32 @@ static inline void early_init_dt_check_for_initrd(unsigned long node)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+/**
+ * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat
+ * tree
+ * @node: reference to node containing elfcorehdr location ('chosen')
+ */
+static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
+{
+	const __be32 *prop;
+	int len;
+
+	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
+		return;
+
+	pr_debug("Looking for elfcorehdr property... ");
+
+	prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+	if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
+		return;
+
+	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n",
+		 elfcorehdr_addr, elfcorehdr_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1055,6 +1082,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 		return 0;
 
 	early_init_dt_check_for_initrd(node);
+	early_init_dt_check_for_elfcorehdr(node);
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
@@ -1199,14 +1227,14 @@ void __init early_init_dt_scan_nodes(void)
 {
 	int rc = 0;
 
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
 	/* Retrieve various information from the /chosen node */
 	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
 	if (!rc)
 		pr_warn("No chosen node found, continuing without\n");
 
-	/* Initialize {size,address}-cells info */
-	of_scan_flat_dt(early_init_dt_scan_root, NULL);
-
 	/* Setup memory, calling early_init_dt_add_memory_arch */
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 }
-- 
2.25.1


_______________________________________________
kexec mailing list
kexec@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/kexec

[PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

[Geert Uytterhoeven]

There are two methods to specify the location of the elf core headers:
using the "elfcorehdr=" kernel parameter, as handled by generic code in
kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the
"/chosen" node in the Device Tree, as handled by architecture-specific
code in arch/arm64/mm/init.c.

Extend support for "linux,elfcorehdr" to all platforms supporting DT by
adding platform-agnostic handling for parsing this property to the FDT
core code.  This can co-exist safely with the architecture-specific
parsing, until the latter has been removed.

This requires moving the call to of_scan_flat_dt() up, as the code
scanning the "/chosen" node now needs to be aware of the values of
"#address-cells" and "#size-cells".

Architecture-specific code still has to reserve the memory used by the
elf core headers, if present.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
About the change to chosen.txt: I have a similar change for
schemas/chosen.yaml in dt-schema.

v4:
  - Use IS_ENABLED() instead of #ifdef,
  - Clarify what architecture-specific code is still responsible for.
---
 Documentation/devicetree/bindings/chosen.txt |  6 ++--
 drivers/of/fdt.c                             | 34 ++++++++++++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 45e79172a646c537..5b0b94eb2d04e79d 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -106,9 +106,9 @@ respectively, of the root node.
 linux,elfcorehdr
 ----------------
 
-This property (currently used only on arm64) holds the memory range,
-the address and the size, of the elf core header which mainly describes
-the panicked kernel's memory layout as PT_LOAD segments of elf format.
+This property holds the memory range, the address and the size, of the elf
+core header which mainly describes the panicked kernel's memory layout as
+PT_LOAD segments of elf format.
 e.g.
 
 / {
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 344f16bb04ccf081..f797d52c5b492cb7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt)	"OF: fdt: " fmt
 
+#include <linux/crash_dump.h>
 #include <linux/crc32.h>
 #include <linux/kernel.h>
 #include <linux/initrd.h>
@@ -908,6 +909,32 @@ static inline void early_init_dt_check_for_initrd(unsigned long node)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+/**
+ * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat
+ * tree
+ * @node: reference to node containing elfcorehdr location ('chosen')
+ */
+static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
+{
+	const __be32 *prop;
+	int len;
+
+	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
+		return;
+
+	pr_debug("Looking for elfcorehdr property... ");
+
+	prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+	if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
+		return;
+
+	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n",
+		 elfcorehdr_addr, elfcorehdr_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1055,6 +1082,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 		return 0;
 
 	early_init_dt_check_for_initrd(node);
+	early_init_dt_check_for_elfcorehdr(node);
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
@@ -1199,14 +1227,14 @@ void __init early_init_dt_scan_nodes(void)
 {
 	int rc = 0;
 
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
 	/* Retrieve various information from the /chosen node */
 	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
 	if (!rc)
 		pr_warn("No chosen node found, continuing without\n");
 
-	/* Initialize {size,address}-cells info */
-	of_scan_flat_dt(early_init_dt_scan_root, NULL);
-
 	/* Setup memory, calling early_init_dt_add_memory_arch */
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 }
-- 
2.25.1


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[PATCH v4 03/10] of: fdt: Add generic support for parsing elf core headers property

[Geert Uytterhoeven]

There are two methods to specify the location of the elf core headers:
using the "elfcorehdr=" kernel parameter, as handled by generic code in
kernel/crash_dump.c, or using the "linux,elfcorehdr" property under the
"/chosen" node in the Device Tree, as handled by architecture-specific
code in arch/arm64/mm/init.c.

Extend support for "linux,elfcorehdr" to all platforms supporting DT by
adding platform-agnostic handling for parsing this property to the FDT
core code.  This can co-exist safely with the architecture-specific
parsing, until the latter has been removed.

This requires moving the call to of_scan_flat_dt() up, as the code
scanning the "/chosen" node now needs to be aware of the values of
"#address-cells" and "#size-cells".

Architecture-specific code still has to reserve the memory used by the
elf core headers, if present.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
About the change to chosen.txt: I have a similar change for
schemas/chosen.yaml in dt-schema.

v4:
  - Use IS_ENABLED() instead of #ifdef,
  - Clarify what architecture-specific code is still responsible for.
---
 Documentation/devicetree/bindings/chosen.txt |  6 ++--
 drivers/of/fdt.c                             | 34 ++++++++++++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/Documentation/devicetree/bindings/chosen.txt b/Documentation/devicetree/bindings/chosen.txt
index 45e79172a646c537..5b0b94eb2d04e79d 100644
--- a/Documentation/devicetree/bindings/chosen.txt
+++ b/Documentation/devicetree/bindings/chosen.txt
@@ -106,9 +106,9 @@ respectively, of the root node.
 linux,elfcorehdr
 ----------------
 
-This property (currently used only on arm64) holds the memory range,
-the address and the size, of the elf core header which mainly describes
-the panicked kernel's memory layout as PT_LOAD segments of elf format.
+This property holds the memory range, the address and the size, of the elf
+core header which mainly describes the panicked kernel's memory layout as
+PT_LOAD segments of elf format.
 e.g.
 
 / {
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 344f16bb04ccf081..f797d52c5b492cb7 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -8,6 +8,7 @@
 
 #define pr_fmt(fmt)	"OF: fdt: " fmt
 
+#include <linux/crash_dump.h>
 #include <linux/crc32.h>
 #include <linux/kernel.h>
 #include <linux/initrd.h>
@@ -908,6 +909,32 @@ static inline void early_init_dt_check_for_initrd(unsigned long node)
 }
 #endif /* CONFIG_BLK_DEV_INITRD */
 
+/**
+ * early_init_dt_check_for_elfcorehdr - Decode elfcorehdr location from flat
+ * tree
+ * @node: reference to node containing elfcorehdr location ('chosen')
+ */
+static void __init early_init_dt_check_for_elfcorehdr(unsigned long node)
+{
+	const __be32 *prop;
+	int len;
+
+	if (!IS_ENABLED(CONFIG_CRASH_DUMP))
+		return;
+
+	pr_debug("Looking for elfcorehdr property... ");
+
+	prop = of_get_flat_dt_prop(node, "linux,elfcorehdr", &len);
+	if (!prop || (len < (dt_root_addr_cells + dt_root_size_cells)))
+		return;
+
+	elfcorehdr_addr = dt_mem_next_cell(dt_root_addr_cells, &prop);
+	elfcorehdr_size = dt_mem_next_cell(dt_root_size_cells, &prop);
+
+	pr_debug("elfcorehdr_start=0x%llx elfcorehdr_size=0x%llx\n",
+		 elfcorehdr_addr, elfcorehdr_size);
+}
+
 #ifdef CONFIG_SERIAL_EARLYCON
 
 int __init early_init_dt_scan_chosen_stdout(void)
@@ -1055,6 +1082,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 		return 0;
 
 	early_init_dt_check_for_initrd(node);
+	early_init_dt_check_for_elfcorehdr(node);
 
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
@@ -1199,14 +1227,14 @@ void __init early_init_dt_scan_nodes(void)
 {
 	int rc = 0;
 
+	/* Initialize {size,address}-cells info */
+	of_scan_flat_dt(early_init_dt_scan_root, NULL);
+
 	/* Retrieve various information from the /chosen node */
 	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
 	if (!rc)
 		pr_warn("No chosen node found, continuing without\n");
 
-	/* Initialize {size,address}-cells info */
-	of_scan_flat_dt(early_init_dt_scan_root, NULL);
-
 	/* Setup memory, calling early_init_dt_add_memory_arch */
 	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
 }
-- 
2.25.1


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