We can skip executing the first "stg" instruction of the patched and disabled mcount code in function tracer enabled kernels. This saves one instruction per function.
Signed-off-by: Heiko Carstens <[email protected]> --- arch/s390/include/asm/ftrace.h | 2 +- arch/s390/kernel/ftrace.c | 16 ++++++++-------- scripts/recordmcount.c | 2 +- scripts/recordmcount.pl | 2 +- 4 files changed, 11 insertions(+), 11 deletions(-) diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h index bf246dae1367..4b264caa0704 100644 --- a/arch/s390/include/asm/ftrace.h +++ b/arch/s390/include/asm/ftrace.h @@ -18,7 +18,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #endif /* __ASSEMBLY__ */ #ifdef CONFIG_64BIT -#define MCOUNT_INSN_SIZE 12 +#define MCOUNT_INSN_SIZE 18 #else #define MCOUNT_INSN_SIZE 22 #endif diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c index 54d6493c4a56..ae4141fbcb07 100644 --- a/arch/s390/kernel/ftrace.c +++ b/arch/s390/kernel/ftrace.c @@ -25,22 +25,22 @@ void ftrace_enable_insn(void); #ifdef CONFIG_64BIT /* * The 64-bit mcount code looks like this: - * stg %r14,8(%r15) # offset 0 + * > stg %r14,8(%r15) # offset 0 * > larl %r1,<&counter> # offset 6 * > brasl %r14,_mcount # offset 12 * lg %r14,8(%r15) # offset 18 - * Total length is 24 bytes. The middle two instructions of the mcount + * Total length is 24 bytes. The first three instructions of the mcount * block get overwritten by ftrace_make_nop / ftrace_make_call. * The 64-bit enabled ftrace code block looks like this: - * stg %r14,8(%r15) # offset 0 + * > stg %r14,8(%r15) # offset 0 * > lg %r1,__LC_FTRACE_FUNC # offset 6 * > lgr %r0,%r0 # offset 12 * > basr %r14,%r1 # offset 16 * lg %r14,8(%15) # offset 18 * The return points of the mcount/ftrace function have the same offset 18. * The 64-bit disable ftrace code block looks like this: - * stg %r14,8(%r15) # offset 0 - * > jg .+18 # offset 6 + * > jg .+24 # offset 6 + * > lg %r1,__LC_FTRACE_FUNC # offset 6 * > lgr %r0,%r0 # offset 12 * > basr %r14,%r1 # offset 16 * lg %r14,8(%15) # offset 18 @@ -50,13 +50,13 @@ void ftrace_enable_insn(void); asm( " .align 4\n" "ftrace_disable_code:\n" - " jg 0f\n" + " jg .+24\n" + " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n" " lgr %r0,%r0\n" " basr %r14,%r1\n" - "0:\n" " .align 4\n" "ftrace_enable_insn:\n" - " lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"); + " stg %r14,8(%r15)\n"); #define FTRACE_INSN_SIZE 6 diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c index 650ecc83d7d7..efca581d8553 100644 --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -408,7 +408,7 @@ do_file(char const *const fname) } if (w2(ghdr->e_machine) == EM_S390) { reltype = R_390_64; - mcount_adjust_64 = -8; + mcount_adjust_64 = -14; } if (w2(ghdr->e_machine) == EM_MIPS) { reltype = R_MIPS_64; diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl index 397b6b84e8c5..2e260fc27a60 100755 --- a/scripts/recordmcount.pl +++ b/scripts/recordmcount.pl @@ -250,7 +250,7 @@ if ($arch eq "x86_64") { } elsif ($arch eq "s390" && $bits == 64) { $mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_390_(PC|PLT)32DBL\\s+_mcount\\+0x2\$"; - $mcount_adjust = -8; + $mcount_adjust = -14; $alignment = 8; $type = ".quad"; $ld .= " -m elf64_s390"; -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
