Re: [PATCH v4 2/5] ia64: reuse append_elf_note() and final_note() functions

From: Dave Young
Date: Thu Jan 05 2017 - 21:03:43 EST


On 01/05/17 at 11:01pm, Hari Bathini wrote:
> Get rid of multiple definitions of append_elf_note() & final_note()
> functions. Reuse these functions compiled under CONFIG_CRASH_CORE
> Also, define Elf_Word and use it instead of generic u32 or the more
> specific Elf64_Word.
>
> Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxxxxxxx>
> ---
>
> Changes from v3:
> * Dropped hard-coded values and used DIV_ROUND_UP().
>
> Changes from v2:
> * Added a definition for Elf_Word.
> * Used IA64 version of append_elf_note() and final_note() functions.
>
>
> arch/ia64/kernel/crash.c | 22 ----------------------
> include/linux/crash_core.h | 4 ++++
> include/linux/elf.h | 2 ++
> kernel/crash_core.c | 34 ++++++++++++++--------------------
> kernel/kexec_core.c | 28 ----------------------------
> 5 files changed, 20 insertions(+), 70 deletions(-)
>
> diff --git a/arch/ia64/kernel/crash.c b/arch/ia64/kernel/crash.c
> index 2955f35..75859a0 100644
> --- a/arch/ia64/kernel/crash.c
> +++ b/arch/ia64/kernel/crash.c
> @@ -27,28 +27,6 @@ static int kdump_freeze_monarch;
> static int kdump_on_init = 1;
> static int kdump_on_fatal_mca = 1;
>
> -static inline Elf64_Word
> -*append_elf_note(Elf64_Word *buf, char *name, unsigned type, void *data,
> - size_t data_len)
> -{
> - struct elf_note *note = (struct elf_note *)buf;
> - note->n_namesz = strlen(name) + 1;
> - note->n_descsz = data_len;
> - note->n_type = type;
> - buf += (sizeof(*note) + 3)/4;
> - memcpy(buf, name, note->n_namesz);
> - buf += (note->n_namesz + 3)/4;
> - memcpy(buf, data, data_len);
> - buf += (data_len + 3)/4;
> - return buf;
> -}
> -
> -static void
> -final_note(void *buf)
> -{
> - memset(buf, 0, sizeof(struct elf_note));
> -}
> -
> extern void ia64_dump_cpu_regs(void *);
>
> static DEFINE_PER_CPU(struct elf_prstatus, elf_prstatus);
> diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
> index 18d0f94..541a197 100644
> --- a/include/linux/crash_core.h
> +++ b/include/linux/crash_core.h
> @@ -55,6 +55,10 @@ extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
> extern size_t vmcoreinfo_size;
> extern size_t vmcoreinfo_max_size;
>
> +Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> + void *data, size_t data_len);
> +void final_note(Elf_Word *buf);
> +
> int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
> unsigned long long *crash_size, unsigned long long *crash_base);
> int parse_crashkernel_high(char *cmdline, unsigned long long system_ram,
> diff --git a/include/linux/elf.h b/include/linux/elf.h
> index 20fa8d8..ba069e8 100644
> --- a/include/linux/elf.h
> +++ b/include/linux/elf.h
> @@ -29,6 +29,7 @@ extern Elf32_Dyn _DYNAMIC [];
> #define elf_note elf32_note
> #define elf_addr_t Elf32_Off
> #define Elf_Half Elf32_Half
> +#define Elf_Word Elf32_Word
>
> #else
>
> @@ -39,6 +40,7 @@ extern Elf64_Dyn _DYNAMIC [];
> #define elf_note elf64_note
> #define elf_addr_t Elf64_Off
> #define Elf_Half Elf64_Half
> +#define Elf_Word Elf64_Word
>
> #endif
>
> diff --git a/kernel/crash_core.c b/kernel/crash_core.c
> index 80b441d..362dace 100644
> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -291,32 +291,26 @@ int __init parse_crashkernel_low(char *cmdline,
> "crashkernel=", suffix_tbl[SUFFIX_LOW]);
> }
>
> -static u32 *append_elf_note(u32 *buf, char *name, unsigned int type,
> - void *data, size_t data_len)
> +Elf_Word *append_elf_note(Elf_Word *buf, char *name, unsigned int type,
> + void *data, size_t data_len)
> {
> - struct elf_note note;
> -
> - note.n_namesz = strlen(name) + 1;
> - note.n_descsz = data_len;
> - note.n_type = type;
> - memcpy(buf, &note, sizeof(note));
> - buf += (sizeof(note) + 3)/4;
> - memcpy(buf, name, note.n_namesz);
> - buf += (note.n_namesz + 3)/4;
> - memcpy(buf, data, note.n_descsz);
> - buf += (note.n_descsz + 3)/4;
> + struct elf_note *note = (struct elf_note *)buf;
> +
> + note->n_namesz = strlen(name) + 1;
> + note->n_descsz = data_len;
> + note->n_type = type;
> + buf += DIV_ROUND_UP(sizeof(*note), sizeof(Elf_Word));
> + memcpy(buf, name, note->n_namesz);
> + buf += DIV_ROUND_UP(note->n_namesz, sizeof(Elf_Word));
> + memcpy(buf, data, data_len);
> + buf += DIV_ROUND_UP(data_len, sizeof(Elf_Word));
>
> return buf;
> }
>
> -static void final_note(u32 *buf)
> +void final_note(Elf_Word *buf)
> {
> - struct elf_note note;
> -
> - note.n_namesz = 0;
> - note.n_descsz = 0;
> - note.n_type = 0;
> - memcpy(buf, &note, sizeof(note));
> + memset(buf, 0, sizeof(struct elf_note));
> }
>
> static void update_vmcoreinfo_note(void)
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index 2179a16..263d764 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -990,34 +990,6 @@ int crash_shrink_memory(unsigned long new_size)
> return ret;
> }
>
> -static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
> - size_t data_len)
> -{
> - struct elf_note note;
> -
> - note.n_namesz = strlen(name) + 1;
> - note.n_descsz = data_len;
> - note.n_type = type;
> - memcpy(buf, &note, sizeof(note));
> - buf += (sizeof(note) + 3)/4;
> - memcpy(buf, name, note.n_namesz);
> - buf += (note.n_namesz + 3)/4;
> - memcpy(buf, data, note.n_descsz);
> - buf += (note.n_descsz + 3)/4;
> -
> - return buf;
> -}
> -
> -static void final_note(u32 *buf)
> -{
> - struct elf_note note;
> -
> - note.n_namesz = 0;
> - note.n_descsz = 0;
> - note.n_type = 0;
> - memcpy(buf, &note, sizeof(note));
> -}
> -
> void crash_save_cpu(struct pt_regs *regs, int cpu)
> {
> struct elf_prstatus prstatus;
>

It looks good to me. But better to have words from IA64 people as well.

Acked-by: Dave Young <dyoung@xxxxxxxxxx>

Thanks
Dave