Hi Pingfan,
On Tue, 18 Jan 2022 15:48:11 +0800
Pingfan Liu <piliu@xxxxxxxxxx> wrote:
> phys_to_virt() calculates virtual address. As a important factor,
> page_offset is excepted to be accurate.
>
> Since arm64 kernel exposes va_bits through vmcore, using it.
>
> Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
> Cc: Kairui Song <kasong@xxxxxxxxxxx>
> Cc: Simon Horman <horms@xxxxxxxxxxxx>
> Cc: Philipp Rudo <prudo@xxxxxxxxxx>
> To: kexec@xxxxxxxxxxxxxxxxxxx
looks good
Reviewed-by: Philipp Rudo <prudo@xxxxxxxxxx>
> ---
> kexec/arch/arm64/kexec-arm64.c | 34 ++++++++++++++++++++++++++++++----
> util_lib/elf_info.c | 5 +++++
> util_lib/include/elf_info.h | 1 +
> 3 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> index 33cc258..793799b 100644
> --- a/kexec/arch/arm64/kexec-arm64.c
> +++ b/kexec/arch/arm64/kexec-arm64.c
> @@ -54,7 +54,7 @@
> static bool try_read_phys_offset_from_kcore = false;
>
> /* Machine specific details. */
> -static int va_bits;
> +static int va_bits = -1;
> static unsigned long page_offset;
>
> /* Global varables the core kexec routines expect. */
> @@ -876,7 +876,18 @@ static inline void set_phys_offset(int64_t v, char *set_method)
>
> static int get_va_bits(void)
> {
> - unsigned long long stext_sym_addr = get_kernel_sym("_stext");
> + unsigned long long stext_sym_addr;
> +
> + /*
> + * if already got from kcore
> + */
> + if (va_bits != -1)
> + goto out;
> +
> +
> + /* For kernel older than v4.19 */
> + fprintf(stderr, "Warning, can't get the VA_BITS from kcore\n");
> + stext_sym_addr = get_kernel_sym("_stext");
>
> if (stext_sym_addr == 0) {
> fprintf(stderr, "Can't get the symbol of _stext.\n");
> @@ -900,6 +911,7 @@ static int get_va_bits(void)
> return -1;
> }
>
> +out:
> dbgprintf("va_bits : %d\n", va_bits);
>
> return 0;
> @@ -917,14 +929,27 @@ int get_page_offset(unsigned long *page_offset)
> if (ret < 0)
> return ret;
>
> - *page_offset = UINT64_MAX << (va_bits - 1);
> + if (va_bits < 52)
> + *page_offset = UINT64_MAX << (va_bits - 1);
> + else
> + *page_offset = UINT64_MAX << va_bits;
> +
> dbgprintf("page_offset : %lx\n", *page_offset);
>
> return 0;
> }
>
> +static void arm64_scan_vmcoreinfo(char *pos)
> +{
> + const char *str;
> +
> + str = "NUMBER(VA_BITS)=";
> + if (memcmp(str, pos, strlen(str)) == 0)
> + va_bits = strtoul(pos + strlen(str), NULL, 10);
> +}
> +
> /**
> - * get_phys_offset_from_vmcoreinfo_pt_note - Helper for getting PHYS_OFFSET
> + * get_phys_offset_from_vmcoreinfo_pt_note - Helper for getting PHYS_OFFSET (and va_bits)
> * from VMCOREINFO note inside 'kcore'.
> */
>
> @@ -937,6 +962,7 @@ static int get_phys_offset_from_vmcoreinfo_pt_note(long *phys_offset)
> return EFAILED;
> }
>
> + arch_scan_vmcoreinfo = arm64_scan_vmcoreinfo;
> ret = read_phys_offset_elf_kcore(fd, phys_offset);
>
> close(fd);
> diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
> index 5574c7f..d252eff 100644
> --- a/util_lib/elf_info.c
> +++ b/util_lib/elf_info.c
> @@ -310,6 +310,8 @@ int get_pt_load(int idx,
>
> #define NOT_FOUND_LONG_VALUE (-1)
>
> +void (*arch_scan_vmcoreinfo)(char *pos);
> +
> void scan_vmcoreinfo(char *start, size_t size)
> {
> char *last = start + size - 1;
> @@ -551,6 +553,9 @@ void scan_vmcoreinfo(char *start, size_t size)
> }
> }
>
> + if (arch_scan_vmcoreinfo != NULL)
> + (*arch_scan_vmcoreinfo)(pos);
> +
> if (last_line)
> break;
> }
> diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h
> index f550d86..fdf4c3d 100644
> --- a/util_lib/include/elf_info.h
> +++ b/util_lib/include/elf_info.h
> @@ -31,5 +31,6 @@ int get_pt_load(int idx,
> int read_phys_offset_elf_kcore(int fd, long *phys_off);
> int read_elf(int fd);
> void dump_dmesg(int fd, void (*handler)(char*, unsigned int));
> +extern void (*arch_scan_vmcoreinfo)(char *pos);
>
> #endif /* ELF_INFO_H */
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