diff options
Diffstat (limited to 'arch/sh/kernel/ftrace.c')
| -rw-r--r-- | arch/sh/kernel/ftrace.c | 60 |
1 files changed, 30 insertions, 30 deletions
diff --git a/arch/sh/kernel/ftrace.c b/arch/sh/kernel/ftrace.c index 4c3247477aa3..066f37dc32a9 100644 --- a/arch/sh/kernel/ftrace.c +++ b/arch/sh/kernel/ftrace.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2008 Matt Fleming <mjf@gentoo.org> + * Copyright (C) 2008 Matt Fleming <matt@console-pimps.org> * Copyright (C) 2008 Paul Mundt <lethal@linux-sh.org> * * Code for replacing ftrace calls with jumps. @@ -19,30 +19,37 @@ #include <asm/ftrace.h> #include <asm/cacheflush.h> -static unsigned char ftrace_nop[] = { - 0x09, 0x00, /* nop */ - 0x09, 0x00, /* nop */ -}; - static unsigned char ftrace_replaced_code[MCOUNT_INSN_SIZE]; -unsigned char *ftrace_nop_replace(void) +static unsigned char ftrace_nop[4]; +/* + * If we're trying to nop out a call to a function, we instead + * place a call to the address after the memory table. + * + * 8c011060 <a>: + * 8c011060: 02 d1 mov.l 8c01106c <a+0xc>,r1 + * 8c011062: 22 4f sts.l pr,@-r15 + * 8c011064: 02 c7 mova 8c011070 <a+0x10>,r0 + * 8c011066: 2b 41 jmp @r1 + * 8c011068: 2a 40 lds r0,pr + * 8c01106a: 09 00 nop + * 8c01106c: 68 24 .word 0x2468 <--- ip + * 8c01106e: 1d 8c .word 0x8c1d + * 8c011070: 26 4f lds.l @r15+,pr <--- ip + MCOUNT_INSN_SIZE + * + * We write 0x8c011070 to 0x8c01106c so that on entry to a() we branch + * past the _mcount call and continue executing code like normal. + */ +static unsigned char *ftrace_nop_replace(unsigned long ip) { + __raw_writel(ip + MCOUNT_INSN_SIZE, ftrace_nop); return ftrace_nop; } -static int is_sh_nop(unsigned char *ip) -{ - return strncmp(ip, ftrace_nop, sizeof(ftrace_nop)); -} - -unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) +static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) { /* Place the address in the memory table. */ - if (addr == CALLER_ADDR) - __raw_writel(addr + MCOUNT_INSN_OFFSET, ftrace_replaced_code); - else - __raw_writel(addr, ftrace_replaced_code); + __raw_writel(addr, ftrace_replaced_code); /* * No locking needed, this must be called via kstop_machine @@ -51,7 +58,7 @@ unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) return ftrace_replaced_code; } -int ftrace_modify_code(unsigned long ip, unsigned char *old_code, +static int ftrace_modify_code(unsigned long ip, unsigned char *old_code, unsigned char *new_code) { unsigned char replaced[MCOUNT_INSN_SIZE]; @@ -66,13 +73,6 @@ int ftrace_modify_code(unsigned long ip, unsigned char *old_code, * kstop_machine, or before SMP starts. */ - /* - * If we're trying to nop out a call to a function, we instead - * place a call to the address after the memory table. - */ - if (is_sh_nop(new_code) == 0) - __raw_writel(ip + MCOUNT_INSN_SIZE, (unsigned long)new_code); - /* read the text we want to modify */ if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE)) return -EFAULT; @@ -92,13 +92,13 @@ int ftrace_modify_code(unsigned long ip, unsigned char *old_code, int ftrace_update_ftrace_func(ftrace_func_t func) { - unsigned long ip = (unsigned long)(&ftrace_call); + unsigned long ip = (unsigned long)(&ftrace_call) + MCOUNT_INSN_OFFSET; unsigned char old[MCOUNT_INSN_SIZE], *new; - memcpy(old, (unsigned char *)(ip + MCOUNT_INSN_OFFSET), MCOUNT_INSN_SIZE); + memcpy(old, (unsigned char *)ip, MCOUNT_INSN_SIZE); new = ftrace_call_replace(ip, (unsigned long)func); - return ftrace_modify_code(ip + MCOUNT_INSN_OFFSET, old, new); + return ftrace_modify_code(ip, old, new); } int ftrace_make_nop(struct module *mod, @@ -108,7 +108,7 @@ int ftrace_make_nop(struct module *mod, unsigned long ip = rec->ip; old = ftrace_call_replace(ip, addr); - new = ftrace_nop_replace(); + new = ftrace_nop_replace(ip); return ftrace_modify_code(rec->ip, old, new); } @@ -118,7 +118,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) unsigned char *new, *old; unsigned long ip = rec->ip; - old = ftrace_nop_replace(); + old = ftrace_nop_replace(ip); new = ftrace_call_replace(ip, addr); return ftrace_modify_code(rec->ip, old, new); |