Le 12/09/2022 à 10:20, Sathvika Vasireddy a écrit :
> This patch enables objtool --mcount on powerpc, and adds implementation
> specific to powerpc.
>
> Signed-off-by: Sathvika Vasireddy <s...@linux.ibm.com>
> ---
> arch/powerpc/Kconfig | 1 +
> tools/objtool/arch/powerpc/decode.c | 16 ++++++++++++++++
> tools/objtool/arch/powerpc/include/arch/elf.h | 2 ++
> 3 files changed, 19 insertions(+)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index dc05cd23c233..6be2e68fa9eb 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -238,6 +238,7 @@ config PPC
> select HAVE_NMI if PERF_EVENTS || (PPC64 &&
> PPC_BOOK3S)
> select HAVE_OPTPROBES
> select HAVE_OBJTOOL if PPC32 || MPROFILE_KERNEL
> + select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
> select HAVE_PERF_EVENTS
> select HAVE_PERF_EVENTS_NMI if PPC64
> select HAVE_PERF_REGS
> diff --git a/tools/objtool/arch/powerpc/decode.c
> b/tools/objtool/arch/powerpc/decode.c
> index dcd0975cad6b..ea2b1968f0ee 100644
> --- a/tools/objtool/arch/powerpc/decode.c
> +++ b/tools/objtool/arch/powerpc/decode.c
> @@ -9,6 +9,11 @@
> #include <objtool/builtin.h>
> #include <objtool/endianness.h>
>
> +int arch_ftrace_match(char *name)
> +{
> + return !strcmp(name, "_mcount");
> +}
> +
> unsigned long arch_dest_reloc_offset(int addend)
> {
> return addend;
> @@ -50,6 +55,17 @@ int arch_decode_instruction(struct objtool_file *file,
> const struct section *sec
> typ = INSN_OTHER;
> imm = 0;
>
> + switch (opcode) {
> + case 18: /* b[l][a] */
> + if (insn & 1) /* bl[a] */
> + typ = INSN_CALL;
If you also handle bla, you need to take it into account in the address
calculation. When second AA bit is set you must calculate the address
accordingly. See
https://patchwork.ozlabs.org/project/linuxppc-dev/patch/ebe11b73d1015a17034a2c4bedf093fa57f5d29f.1662032631.git.christophe.le...@csgroup.eu/
> +
> + imm = insn & 0x3fffffc;
> + if (imm & 0x2000000)
> + imm -= 0x4000000;
> + break;
> + }
> +
> if (opcode == 1)
> *len = 8;
> else
> diff --git a/tools/objtool/arch/powerpc/include/arch/elf.h
> b/tools/objtool/arch/powerpc/include/arch/elf.h
> index 3c8ebb7d2a6b..73f9ae172fe5 100644
> --- a/tools/objtool/arch/powerpc/include/arch/elf.h
> +++ b/tools/objtool/arch/powerpc/include/arch/elf.h
> @@ -4,5 +4,7 @@
> #define _OBJTOOL_ARCH_ELF
>
> #define R_NONE R_PPC_NONE
> +#define R_ABS64 R_PPC64_ADDR64
> +#define R_ABS32 R_PPC_ADDR32
>
> #endif /* _OBJTOOL_ARCH_ELF */
