csky/ftrace: Add dynamic function tracer (include graph tracer)

Support dynamic ftrace including dynamic graph tracer. Gcc-csky with -pg
will produce call site in every function prologue and we can use these
call site to hook trace function.

gcc with -pg origin call site:
	push	lr
	jbsr	_mcount
	nop32
	nop32

If the (callee - caller)'s offset is in range of bsr instruction, we'll
modify code with:
	push	lr
	bsr	_mcount
	nop32
	nop32
Else if the (callee - caller)'s offset is out of bsr instrunction, we'll
modify code with:
	push	lr
	movih	r26, ...
	ori	r26, ...
	jsr	r26

(r26 is reserved for jsr link reg in csky abiv2 spec.)

Signed-off-by: Guo Ren <ren_guo@c-sky.com>
This commit is contained in:
Guo Ren 2019-03-01 08:50:36 +08:00
parent 3dfc242f11
commit 28bb030f93
5 changed files with 205 additions and 6 deletions

View File

@ -29,13 +29,14 @@ config CSKY
select GENERIC_SCHED_CLOCK
select GENERIC_SMP_IDLE_THREAD
select HAVE_ARCH_TRACEHOOK
select HAVE_DYNAMIC_FTRACE
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_KERNEL_GZIP
select HAVE_KERNEL_LZO
select HAVE_KERNEL_LZMA
select HAVE_PERF_EVENTS
select HAVE_C_RECORDMCOUNT
select HAVE_DMA_API_DEBUG
select HAVE_DMA_CONTIGUOUS
select MAY_HAVE_SPARSE_IRQ

View File

@ -61,10 +61,17 @@
addi sp, 16
.endm
.macro nop32_stub
nop32
nop32
nop32
.endm
ENTRY(ftrace_stub)
jmp lr
END(ftrace_stub)
#ifndef CONFIG_DYNAMIC_FTRACE
ENTRY(_mcount)
mcount_enter
@ -76,7 +83,7 @@ ENTRY(_mcount)
bf skip_ftrace
mov a0, lr
subi a0, MCOUNT_INSN_SIZE
subi a0, 4
ldw a1, (sp, 24)
jsr r26
@ -101,13 +108,41 @@ skip_ftrace:
mcount_exit
#endif
END(_mcount)
#else /* CONFIG_DYNAMIC_FTRACE */
ENTRY(_mcount)
mov t1, lr
ldw lr, (sp, 0)
addi sp, 4
jmp t1
ENDPROC(_mcount)
ENTRY(ftrace_caller)
mcount_enter
ldw a0, (sp, 16)
subi a0, 4
ldw a1, (sp, 24)
nop
GLOBAL(ftrace_call)
nop32_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
nop
GLOBAL(ftrace_graph_call)
nop32_stub
#endif
mcount_exit
ENDPROC(ftrace_caller)
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
ENTRY(ftrace_graph_caller)
mov a0, sp
addi a0, 24
ldw a1, (sp, 16)
subi a1, MCOUNT_INSN_SIZE
subi a1, 4
mov a2, r8
lrw r26, prepare_ftrace_return
jsr r26

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@ -4,10 +4,26 @@
#ifndef __ASM_CSKY_FTRACE_H
#define __ASM_CSKY_FTRACE_H
#define MCOUNT_INSN_SIZE 4
#define MCOUNT_INSN_SIZE 14
#define HAVE_FUNCTION_GRAPH_FP_TEST
#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
#define MCOUNT_ADDR ((unsigned long)_mcount)
#ifndef __ASSEMBLY__
extern void _mcount(unsigned long);
extern void ftrace_graph_call(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
return addr;
}
struct dyn_arch_ftrace {
};
#endif /* !__ASSEMBLY__ */
#endif /* __ASM_CSKY_FTRACE_H */

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@ -3,6 +3,137 @@
#include <linux/ftrace.h>
#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#ifdef CONFIG_DYNAMIC_FTRACE
#define NOP 0x4000
#define NOP32_HI 0xc400
#define NOP32_LO 0x4820
#define PUSH_LR 0x14d0
#define MOVIH_LINK 0xea3a
#define ORI_LINK 0xef5a
#define JSR_LINK 0xe8fa
#define BSR_LINK 0xe000
/*
* Gcc-csky with -pg will insert stub in function prologue:
* push lr
* jbsr _mcount
* nop32
* nop32
*
* If the (callee - current_pc) is less then 64MB, we'll use bsr:
* push lr
* bsr _mcount
* nop32
* nop32
* else we'll use (movih + ori + jsr):
* push lr
* movih r26, ...
* ori r26, ...
* jsr r26
*
* (r26 is our reserved link-reg)
*
*/
static inline void make_jbsr(unsigned long callee, unsigned long pc,
uint16_t *call, bool nolr)
{
long offset;
call[0] = nolr ? NOP : PUSH_LR;
offset = (long) callee - (long) pc;
if (unlikely(offset < -67108864 || offset > 67108864)) {
call[1] = MOVIH_LINK;
call[2] = callee >> 16;
call[3] = ORI_LINK;
call[4] = callee & 0xffff;
call[5] = JSR_LINK;
call[6] = 0;
} else {
offset = offset >> 1;
call[1] = BSR_LINK |
((uint16_t)((unsigned long) offset >> 16) & 0x3ff);
call[2] = (uint16_t)((unsigned long) offset & 0xffff);
call[3] = call[5] = NOP32_HI;
call[4] = call[6] = NOP32_LO;
}
}
static uint16_t nops[7] = {NOP, NOP32_HI, NOP32_LO, NOP32_HI, NOP32_LO,
NOP32_HI, NOP32_LO};
static int ftrace_check_current_nop(unsigned long hook)
{
uint16_t olds[7];
unsigned long hook_pos = hook - 2;
if (probe_kernel_read((void *)olds, (void *)hook_pos, sizeof(nops)))
return -EFAULT;
if (memcmp((void *)nops, (void *)olds, sizeof(nops))) {
pr_err("%p: nop but get (%04x %04x %04x %04x %04x %04x %04x)\n",
(void *)hook_pos,
olds[0], olds[1], olds[2], olds[3], olds[4], olds[5],
olds[6]);
return -EINVAL;
}
return 0;
}
static int ftrace_modify_code(unsigned long hook, unsigned long target,
bool enable, bool nolr)
{
uint16_t call[7];
unsigned long hook_pos = hook - 2;
int ret = 0;
make_jbsr(target, hook, call, nolr);
ret = probe_kernel_write((void *)hook_pos, enable ? call : nops,
sizeof(nops));
if (ret)
return -EPERM;
flush_icache_range(hook_pos, hook_pos + MCOUNT_INSN_SIZE);
return 0;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
int ret = ftrace_check_current_nop(rec->ip);
if (ret)
return ret;
return ftrace_modify_code(rec->ip, addr, true, false);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
return ftrace_modify_code(rec->ip, addr, false, false);
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
int ret = ftrace_modify_code((unsigned long)&ftrace_call,
(unsigned long)func, true, true);
return ret;
}
int __init ftrace_dyn_arch_init(void)
{
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
@ -43,8 +174,21 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
*(unsigned long *)frame_pointer = return_hooker;
}
}
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
int ftrace_enable_ftrace_graph_caller(void)
{
return ftrace_modify_code((unsigned long)&ftrace_graph_call,
(unsigned long)&ftrace_graph_caller, true, true);
}
int ftrace_disable_ftrace_graph_caller(void)
{
return ftrace_modify_code((unsigned long)&ftrace_graph_call,
(unsigned long)&ftrace_graph_caller, false, true);
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
/* _mcount is defined in abi's mcount.S */
extern void _mcount(void);
EXPORT_SYMBOL(_mcount);

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@ -397,6 +397,9 @@ if ($arch eq "x86_64") {
} elsif ($arch eq "nds32") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_NDS32_HI20_RELA\\s+_mcount\$";
$alignment = 2;
} elsif ($arch eq "csky") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):\\s*R_CKCORE_PCREL_JSR_IMM26BY2\\s+_mcount\$";
$alignment = 2;
} else {
die "Arch $arch is not supported with CONFIG_FTRACE_MCOUNT_RECORD";
}