The changes are absolutely not specific to powerpc. You should adjust
the subject accordingly, and copy linux-arch and tracing and probably
also ia64 and parisc.
Le 12/12/2022 à 22:21, Michael Jeanson a écrit :
> In ad050d2390fccb22aa3e6f65e11757ce7a5a7ca5 we fixed ftrace syscall
> tracing on PPC64_ELF_ABI_V1 by looking for the non-dot prefixed symbol
> of a syscall.
Should be written as:
Commit ad050d2390fc ("powerpc/ftrace: fix syscall tracing on
PPC64_ELF_ABI_V1") fixed ....
>
> Ftrace uses kallsyms to locate syscall symbols and those non-dot
> prefixed symbols reside in a separate '.opd' section which is not
> included by kallsyms.
>
> So we either need to have FTRACE_SYSCALLS select KALLSYMS_ALL on
> PPC64_ELF_ABI_V1 or add the '.opd' section symbols to kallsyms.
>
> This patch does the minimum to achieve the latter, it's tested on a
> corenet64_smp_defconfig with KALLSYMS_ALL turned off.
>
> I'm unsure which of the alternatives would be better.
>
> ---
> In 'kernel/module/kallsyms.c' the 'is_core_symbol' function might also
> require some tweaking to make all opd symbols available to kallsyms but
> that doesn't impact ftrace syscall tracing.
>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
> Signed-off-by: Michael Jeanson <mjeanson@xxxxxxxxxxxx>
> ---
> include/asm-generic/sections.h | 14 ++++++++++++++
> include/linux/kallsyms.h | 3 +++
> kernel/kallsyms.c | 2 ++
> scripts/kallsyms.c | 1 +
> 4 files changed, 20 insertions(+)
>
> diff --git a/include/asm-generic/sections.h b/include/asm-generic/sections.h
> index db13bb620f52..1410566957e5 100644
> --- a/include/asm-generic/sections.h
> +++ b/include/asm-generic/sections.h
> @@ -180,6 +180,20 @@ static inline bool is_kernel_rodata(unsigned long addr)
> addr < (unsigned long)__end_rodata;
> }
>
> +/**
> + * is_kernel_opd - checks if the pointer address is located in the
> + * .opd section
> + *
> + * @addr: address to check
> + *
> + * Returns: true if the address is located in .opd, false otherwise.
> + */
> +static inline bool is_kernel_opd(unsigned long addr)
> +{
I would add a check of CONFIG_HAVE_FUNCTION_DESCRIPTORS:
if (!IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS))
return false;
> + return addr >= (unsigned long)__start_opd &&
> + addr < (unsigned long)__end_opd;
> +}
> +
> /**
> * is_kernel_inittext - checks if the pointer address is located in the
> * .init.text section
> diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h
> index 649faac31ddb..9bfb4d8d41a5 100644
> --- a/include/linux/kallsyms.h
> +++ b/include/linux/kallsyms.h
> @@ -43,6 +43,9 @@ static inline int is_ksym_addr(unsigned long addr)
> if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
> return is_kernel(addr);
>
> + if (IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS))
> + return is_kernel_text(addr) || is_kernel_inittext(addr) || is_kernel_opd(addr);
> +
With the check inside is_kernel_opd(), you can make it simpler:
return is_kernel_text(addr) || is_kernel_inittext(addr) ||
is_kernel_opd(addr);
> return is_kernel_text(addr) || is_kernel_inittext(addr);
> }
>
> diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c
> index 60c20f301a6b..009b1ca21618 100644
> --- a/kernel/kallsyms.c
> +++ b/kernel/kallsyms.c
> @@ -281,6 +281,8 @@ static unsigned long get_symbol_pos(unsigned long addr,
> symbol_end = (unsigned long)_einittext;
> else if (IS_ENABLED(CONFIG_KALLSYMS_ALL))
> symbol_end = (unsigned long)_end;
> + else if (IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS) && is_kernel_opd(addr))
> + symbol_end = (unsigned long)__end_opd;
Same, with the check included inside is_kernel_opd() you don't need the
IS_ENABLED(CONFIG_HAVE_FUNCTION_DESCRIPTORS) here.
> else
> symbol_end = (unsigned long)_etext;
> }
> diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
> index 03fa07ad45d9..decf31c497f5 100644
> --- a/scripts/kallsyms.c
> +++ b/scripts/kallsyms.c
> @@ -64,6 +64,7 @@ static unsigned long long relative_base;
> static struct addr_range text_ranges[] = {
> { "_stext", "_etext" },
> { "_sinittext", "_einittext" },
> + { "__start_opd", "__end_opd" },
> };
> #define text_range_text (&text_ranges[0])
> #define text_range_inittext (&text_ranges[1])
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