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of: fdt: Add generic support for handling elf core headers property

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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 handling this property to the FDT
core code.  This can co-exist safely with the architecture-specific
handling, 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".

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/c7e46e50aaf87ef49bdaa61358d25b122f32b7df.1628670468.git.geert+renesas@glider.be
This commit is contained in:
Geert Uytterhoeven 2021-08-11 10:51:01 +02:00 committed by Rob Herring
parent 3370941301
commit f7e7ce93aa
2 changed files with 59 additions and 6 deletions
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6
Documentation/devicetree/bindings/chosen.txt
View File

@ -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.
/ {

59
drivers/of/fdt.c
View File

@ -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>
@ -597,6 +598,30 @@ static int __init __fdt_scan_reserved_mem(unsigned long node, const char *uname,
return 0;
}
/*
* reserve_elfcorehdr() - reserves memory for elf core header
*
* This function reserves the memory occupied by an elf core header
* described in the device tree. This region contains all the
* information about primary kernel's core image and is used by a dump
* capture kernel to access the system memory on primary kernel.
*/
static void __init reserve_elfcorehdr(void)
{
if (!IS_ENABLED(CONFIG_CRASH_DUMP) || !elfcorehdr_size)
return;
if (memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)) {
pr_warn("elfcorehdr is overlapped\n");
return;
}
memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
pr_info("Reserving %llu KiB of memory at 0x%llx for elfcorehdr\n",
elfcorehdr_size >> 10, elfcorehdr_addr);
}
/**
* early_init_fdt_scan_reserved_mem() - create reserved memory regions
*
@ -622,6 +647,7 @@ void __init early_init_fdt_scan_reserved_mem(void)
of_scan_flat_dt(__fdt_scan_reserved_mem, NULL);
fdt_init_reserved_mem();
reserve_elfcorehdr();
}
/**
@ -920,6 +946,32 @@ 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)
@ -1067,6 +1119,7 @@ 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);
@ -1190,14 +1243,14 @@ 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);
}