on 2015/10/30 16:31, Li Bin wrote: > By now, the recordmcount only records the function that in > following sections: > .text/.ref.text/.sched.text/.spinlock.text/.irqentry.text/ > .kprobes.text/.text.unlikely > > For the function that not in these sections, the call mcount > will be in place and not be replaced when kernel boot up. And > it will bring performance overhead, such as do_mem_abort (in > .exception.text section). This patch make the call mcount to > nop for this case in recordmcount. > > Cc: <sta...@vger.kernel.org> # 3.18+ > Signed-off-by: Li Bin <huawei.li...@huawei.com>
Acked-by: Will Deacon <will.dea...@arm.com> https://lkml.org/lkml/2015/10/28/301 > --- > scripts/recordmcount.c | 24 +++++++++++++++++++++++- > 1 file changed, 23 insertions(+), 1 deletion(-) > > diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c > index 8cc020b..698768b 100644 > --- a/scripts/recordmcount.c > +++ b/scripts/recordmcount.c > @@ -42,6 +42,7 @@ > > #ifndef EM_AARCH64 > #define EM_AARCH64 183 > +#define R_AARCH64_NONE 0 > #define R_AARCH64_ABS64 257 > #endif > > @@ -160,6 +161,22 @@ static int make_nop_x86(void *map, size_t const offset) > return 0; > } > > +static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5}; > +static int make_nop_arm64(void *map, size_t const offset) > +{ > + uint32_t *ptr; > + > + ptr = map + offset; > + /* bl <_mcount> is 0x94000000 before relocation */ > + if (*ptr != 0x94000000) > + return -1; > + > + /* Convert to nop */ > + ulseek(fd_map, offset, SEEK_SET); > + uwrite(fd_map, ideal_nop, 4); > + return 0; > +} > + > /* > * Get the whole file as a programming convenience in order to avoid > * malloc+lseek+read+free of many pieces. If successful, then mmap > @@ -354,7 +371,12 @@ do_file(char const *const fname) > altmcount = "__gnu_mcount_nc"; > break; > case EM_AARCH64: > - reltype = R_AARCH64_ABS64; gpfx = '_'; break; > + reltype = R_AARCH64_ABS64; > + make_nop = make_nop_arm64; > + rel_type_nop = R_AARCH64_NONE; > + ideal_nop = ideal_nop4_arm64; > + gpfx = '_'; > + break; > case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break; > case EM_METAG: reltype = R_METAG_ADDR32; > altmcount = "_mcount_wrapper"; > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
