Re: [PATCH] MIPS: Use common way to parse elfcorehdr

[Jinyang He]

On 02/04/2021 11:28 AM, Randy Dunlap wrote:

On 2/3/21 7:07 PM, Jinyang He wrote:

"elfcorehdr" can be parsed at kernel/crash_dump.c

Signed-off-by: Jinyang He <hejiny...@loongson.cn>

Hm, looks like that would require CONFIG_CRASH_DUMP?

Hi,

I don't think so. We expect to generate a /proc/vmcore when we reserved
memory for elfcorehdr. So put it under CONFIG_PROC_VMCORE. If only rely
on CONFIG_CRASH_DUMP and CONFIG_PROC_VMCORE is not enabled, we will
reserve these memory while cannot use these later. And the reason why
kernel/crash_dump.c being under CONFIG_CRASH_DUMP is that it provide
is_kdump_kernel() for others.

Thanks,
Jinyang

---
  arch/mips/kernel/setup.c | 49 +++++++++++++++++++++---------------------------
  1 file changed, 21 insertions(+), 28 deletions(-)

diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 7e1f8e2..4d2f915 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -29,6 +29,7 @@
  #include <linux/of_fdt.h>
  #include <linux/of_reserved_mem.h>
  #include <linux/dmi.h>
+#include <linux/crash_dump.h>

#include <asm/addrspace.h>

  #include <asm/bootinfo.h>
@@ -404,34 +405,32 @@ static int __init early_parse_memmap(char *p)
  }
  early_param("memmap", early_parse_memmap);

-#ifdef CONFIG_PROC_VMCORE

-static unsigned long setup_elfcorehdr, setup_elfcorehdr_size;
-static int __init early_parse_elfcorehdr(char *p)
+static void __init mips_reserve_vmcore(void)
  {
+#ifdef CONFIG_PROC_VMCORE
        phys_addr_t start, end;
        u64 i;

- setup_elfcorehdr = memparse(p, &p);

-
-       for_each_mem_range(i, &start, &end) {
-               if (setup_elfcorehdr >= start && setup_elfcorehdr < end) {
-                       /*
-                        * Reserve from the elf core header to the end of
-                        * the memory segment, that should all be kdump
-                        * reserved memory.
-                        */
-                       setup_elfcorehdr_size = end - setup_elfcorehdr;
-                       break;
+       if (!elfcorehdr_size) {
+               for_each_mem_range(i, &start, &end) {
+                       if (elfcorehdr_addr >= start && elfcorehdr_addr < end) {
+                               /*
+                                * Reserve from the elf core header to the end 
of
+                                * the memory segment, that should all be kdump
+                                * reserved memory.
+                                */
+                               elfcorehdr_size = end - elfcorehdr_addr;
+                               break;
+                       }
                }
        }
-       /*
-        * If we don't find it in the memory map, then we shouldn't
-        * have to worry about it, as the new kernel won't use it.
-        */
-       return 0;
-}
-early_param("elfcorehdr", early_parse_elfcorehdr);
+
+       pr_info("Reserving %ldKB of memory at %ldKB for kdump\n",
+               (unsigned long)elfcorehdr_size >> 10, (unsigned long)elfcorehdr_addr 
>> 10);
+
+       memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
  #endif
+}

#ifdef CONFIG_KEXEC @@ -653,13 +652,7 @@ static void __init arch_mem_init(char **cmdline_p)

         */
        memblock_set_current_limit(PFN_PHYS(max_low_pfn));

-#ifdef CONFIG_PROC_VMCORE

-       if (setup_elfcorehdr && setup_elfcorehdr_size) {
-               printk(KERN_INFO "kdump reserved memory at %lx-%lx\n",
-                      setup_elfcorehdr, setup_elfcorehdr_size);
-               memblock_reserve(setup_elfcorehdr, setup_elfcorehdr_size);
-       }
-#endif
+       mips_reserve_vmcore();

mips_parse_crashkernel();

  #ifdef CONFIG_KEXEC