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ARM: ftrace: graph tracer + dynamic ftrace

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Support the graph tracer + dynamic ftrace combination on ARM.

Signed-off-by: Rabin Vincent <rabin@rab.in>
This commit is contained in:
Rabin Vincent 2010-11-06 23:03:21 +05:30
parent 376cfa8730
commit dd686eb139
2 changed files with 76 additions and 5 deletions
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12
arch/arm/kernel/entry-common.S
View file

@ -183,12 +183,24 @@ ENDPROC(ret_from_fork)
ftrace_call\suffix:
bl ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.globl ftrace_graph_call\suffix
ftrace_graph_call\suffix:
mov r0, r0
#endif
mcount_exit
.endm
.macro __ftrace_graph_caller
sub r0, fp, #4 @ &lr of instrumented routine (&parent)
#ifdef CONFIG_DYNAMIC_FTRACE
@ called from __ftrace_caller, saved in mcount_enter
ldr r1, [sp, #16] @ instrumented routine (func)
#else
@ called from __mcount, untouched in lr
mov r1, lr @ instrumented routine (func)
#endif
sub r1, r1, #MCOUNT_INSN_SIZE
mov r2, fp @ frame pointer
bl prepare_ftrace_return

69
arch/arm/kernel/ftrace.c
View file

@ -60,9 +60,9 @@ static unsigned long adjust_address(struct dyn_ftrace *rec, unsigned long addr)
}
#endif
/* construct a branch (BL) instruction to addr */
#ifdef CONFIG_THUMB2_KERNEL
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
bool link)
{
unsigned long s, j1, j2, i1, i2, imm10, imm11;
unsigned long first, second;
@ -84,15 +84,22 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
j2 = (!i2) ^ s;
first = 0xf000 | (s << 10) | imm10;
second = 0xd000 | (j1 << 13) | (j2 << 11) | imm11;
second = 0x9000 | (j1 << 13) | (j2 << 11) | imm11;
if (link)
second |= 1 << 14;
return (second << 16) | first;
}
#else
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
static unsigned long ftrace_gen_branch(unsigned long pc, unsigned long addr,
bool link)
{
unsigned long opcode = 0xea000000;
long offset;
if (link)
opcode |= 1 << 24;
offset = (long)addr - (long)(pc + 8);
if (unlikely(offset < -33554432 || offset > 33554428)) {
/* Can't generate branches that far (from ARM ARM). Ftrace
@ -104,10 +111,15 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
offset = (offset >> 2) & 0x00ffffff;
return 0xeb000000 | offset;
return opcode | offset;
}
#endif
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
return ftrace_gen_branch(pc, addr, true);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
unsigned long new)
{
@ -226,4 +238,51 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
*parent = old;
}
}
#ifdef CONFIG_DYNAMIC_FTRACE
extern unsigned long ftrace_graph_call;
extern unsigned long ftrace_graph_call_old;
extern void ftrace_graph_caller_old(void);
static int __ftrace_modify_caller(unsigned long *callsite,
void (*func) (void), bool enable)
{
unsigned long caller_fn = (unsigned long) func;
unsigned long pc = (unsigned long) callsite;
unsigned long branch = ftrace_gen_branch(pc, caller_fn, false);
unsigned long nop = 0xe1a00000; /* mov r0, r0 */
unsigned long old = enable ? nop : branch;
unsigned long new = enable ? branch : nop;
return ftrace_modify_code(pc, old, new);
}
static int ftrace_modify_graph_caller(bool enable)
{
int ret;
ret = __ftrace_modify_caller(&ftrace_graph_call,
ftrace_graph_caller,
enable);
#ifdef CONFIG_OLD_MCOUNT
if (!ret)
ret = __ftrace_modify_caller(&ftrace_graph_call_old,
ftrace_graph_caller_old,
enable);
#endif
return ret;
}
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_graph_caller(false);
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */