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[S390] cleanup ftrace backend functions

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Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2011-01-05 12:48:11 +01:00 committed by Martin Schwidefsky
parent 5e9a26928f
commit 4cc9bed034
4 changed files with 135 additions and 171 deletions
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11
arch/s390/include/asm/ftrace.h
View File

@ -4,20 +4,17 @@
#ifndef __ASSEMBLY__
extern void _mcount(void);
extern unsigned long ftrace_dyn_func;
struct dyn_arch_ftrace { };
#define MCOUNT_ADDR ((long)_mcount)
#ifdef CONFIG_64BIT
#define MCOUNT_OFFSET_RET 18
#define MCOUNT_INSN_SIZE 24
#define MCOUNT_OFFSET 14
#else
#define MCOUNT_OFFSET_RET 26
#define MCOUNT_INSN_SIZE 30
#define MCOUNT_INSN_SIZE 12
#define MCOUNT_OFFSET 8
#else
#define MCOUNT_INSN_SIZE 20
#define MCOUNT_OFFSET 4
#endif
static inline unsigned long ftrace_call_adjust(unsigned long addr)

238
arch/s390/kernel/ftrace.c
View File

@ -4,7 +4,7 @@
* Copyright IBM Corp. 2009
*
* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>,
*
* Martin Schwidefsky <schwidefsky@de.ibm.com>
*/
#include <linux/hardirq.h>
@ -12,176 +12,144 @@
#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/kprobes.h>
#include <trace/syscall.h>
#include <asm/asm-offsets.h>
#ifdef CONFIG_64BIT
#define MCOUNT_OFFSET_RET 12
#else
#define MCOUNT_OFFSET_RET 22
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
void ftrace_disable_code(void);
void ftrace_disable_return(void);
void ftrace_call_code(void);
void ftrace_nop_code(void);
#define FTRACE_INSN_SIZE 4
void ftrace_enable_insn(void);
#ifdef CONFIG_64BIT
/*
* The 64-bit mcount code looks like this:
* 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
* 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
* > 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
* > lgr %r0,%r0 # offset 12
* > basr %r14,%r1 # offset 16
* lg %r14,8(%15) # offset 18
* The jg instruction branches to offset 24 to skip as many instructions
* as possible.
*/
asm(
" .align 4\n"
"ftrace_disable_code:\n"
" j 0f\n"
" .word 0x0024\n"
" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
" basr %r14,%r1\n"
"ftrace_disable_return:\n"
" lg %r14,8(15)\n"
" jg 0f\n"
" lgr %r0,%r0\n"
"0:\n");
asm(
" basr %r14,%r1\n"
"0:\n"
" .align 4\n"
"ftrace_nop_code:\n"
" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
"ftrace_enable_insn:\n"
" lg %r1,"__stringify(__LC_FTRACE_FUNC)"\n");
asm(
" .align 4\n"
"ftrace_call_code:\n"
" stg %r14,8(%r15)\n");
#define FTRACE_INSN_SIZE 6
#else /* CONFIG_64BIT */
/*
* The 31-bit mcount code looks like this:
* st %r14,4(%r15) # offset 0
* > bras %r1,0f # offset 4
* > .long _mcount # offset 8
* > .long <&counter> # offset 12
* > 0: l %r14,0(%r1) # offset 16
* > l %r1,4(%r1) # offset 20
* basr %r14,%r14 # offset 24
* l %r14,4(%r15) # offset 26
* Total length is 30 bytes. The twenty bytes starting from offset 4
* to offset 24 get overwritten by ftrace_make_nop / ftrace_make_call.
* The 31-bit enabled ftrace code block looks like this:
* st %r14,4(%r15) # offset 0
* > l %r14,__LC_FTRACE_FUNC # offset 4
* > j 0f # offset 8
* > .fill 12,1,0x07 # offset 12
* 0: basr %r14,%r14 # offset 24
* l %r14,4(%r14) # offset 26
* The return points of the mcount/ftrace function have the same offset 26.
* The 31-bit disabled ftrace code block looks like this:
* st %r14,4(%r15) # offset 0
* > j .+26 # offset 4
* > j 0f # offset 8
* > .fill 12,1,0x07 # offset 12
* 0: basr %r14,%r14 # offset 24
* l %r14,4(%r14) # offset 26
* The j instruction branches to offset 30 to skip as many instructions
* as possible.
*/
asm(
" .align 4\n"
"ftrace_disable_code:\n"
" j 1f\n"
" j 0f\n"
" l %r1,"__stringify(__LC_FTRACE_FUNC)"\n"
" basr %r14,%r1\n"
"ftrace_disable_return:\n"
" l %r14,4(%r15)\n"
" j 0f\n"
" bcr 0,%r7\n"
" bcr 0,%r7\n"
" bcr 0,%r7\n"
" bcr 0,%r7\n"
" bcr 0,%r7\n"
" bcr 0,%r7\n"
"0:\n");
asm(
" .fill 12,1,0x07\n"
"0: basr %r14,%r14\n"
"1:\n"
" .align 4\n"
"ftrace_nop_code:\n"
" j .+"__stringify(MCOUNT_INSN_SIZE)"\n");
"ftrace_enable_insn:\n"
" l %r14,"__stringify(__LC_FTRACE_FUNC)"\n");
asm(
" .align 4\n"
"ftrace_call_code:\n"
" st %r14,4(%r15)\n");
#define FTRACE_INSN_SIZE 4
#endif /* CONFIG_64BIT */
static int ftrace_modify_code(unsigned long ip,
void *old_code, int old_size,
void *new_code, int new_size)
{
unsigned char replaced[MCOUNT_INSN_SIZE];
/*
* Note: Due to modules code can disappear and change.
* We need to protect against faulting as well as code
* changing. We do this by using the probe_kernel_*
* functions.
* This however is just a simple sanity check.
*/
if (probe_kernel_read(replaced, (void *)ip, old_size))
return -EFAULT;
if (memcmp(replaced, old_code, old_size) != 0)
return -EINVAL;
if (probe_kernel_write((void *)ip, new_code, new_size))
return -EPERM;
return 0;
}
static int ftrace_make_initial_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
return ftrace_modify_code(rec->ip,
ftrace_call_code, FTRACE_INSN_SIZE,
ftrace_disable_code, MCOUNT_INSN_SIZE);
}
int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
if (addr == MCOUNT_ADDR)
return ftrace_make_initial_nop(mod, rec, addr);
return ftrace_modify_code(rec->ip,
ftrace_call_code, FTRACE_INSN_SIZE,
ftrace_nop_code, FTRACE_INSN_SIZE);
if (probe_kernel_write((void *) rec->ip, ftrace_disable_code,
MCOUNT_INSN_SIZE))
return -EPERM;
return 0;
}
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
return ftrace_modify_code(rec->ip,
ftrace_nop_code, FTRACE_INSN_SIZE,
ftrace_call_code, FTRACE_INSN_SIZE);
if (probe_kernel_write((void *) rec->ip, ftrace_enable_insn,
FTRACE_INSN_SIZE))
return -EPERM;
return 0;
}
int ftrace_update_ftrace_func(ftrace_func_t func)
{
ftrace_dyn_func = (unsigned long)func;
return 0;
}
int __init ftrace_dyn_arch_init(void *data)
{
*(unsigned long *)data = 0;
*(unsigned long *) data = 0;
return 0;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
/*
* Patch the kernel code at ftrace_graph_caller location:
* The instruction there is branch relative on condition. The condition mask
* is either all ones (always branch aka disable ftrace_graph_caller) or all
* zeroes (nop aka enable ftrace_graph_caller).
* Instruction format for brc is a7m4xxxx where m is the condition mask.
*/
int ftrace_enable_ftrace_graph_caller(void)
{
unsigned short opcode = 0xa704;
return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
}
int ftrace_disable_ftrace_graph_caller(void)
{
unsigned short opcode = 0xa7f4;
return probe_kernel_write(ftrace_graph_caller, &opcode, sizeof(opcode));
}
static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
{
return addr - (ftrace_disable_return - ftrace_disable_code);
}
#else /* CONFIG_DYNAMIC_FTRACE */
static inline unsigned long ftrace_mcount_call_adjust(unsigned long addr)
{
return addr - MCOUNT_OFFSET_RET;
}
#endif /* CONFIG_DYNAMIC_FTRACE */
/*
* Hook the return address and push it in the stack of return addresses
* in current thread info.
*/
unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
unsigned long __kprobes prepare_ftrace_return(unsigned long parent,
unsigned long ip)
{
struct ftrace_graph_ent trace;
@ -189,14 +157,42 @@ unsigned long prepare_ftrace_return(unsigned long ip, unsigned long parent)
goto out;
if (ftrace_push_return_trace(parent, ip, &trace.depth, 0) == -EBUSY)
goto out;
trace.func = ftrace_mcount_call_adjust(ip) & PSW_ADDR_INSN;
trace.func = (ip & PSW_ADDR_INSN) - MCOUNT_OFFSET_RET;
/* Only trace if the calling function expects to. */
if (!ftrace_graph_entry(&trace)) {
current->curr_ret_stack--;
goto out;
}
parent = (unsigned long)return_to_handler;
parent = (unsigned long) return_to_handler;
out:
return parent;
}
#ifdef CONFIG_DYNAMIC_FTRACE
/*
* Patch the kernel code at ftrace_graph_caller location. The instruction
* there is branch relative and save to prepare_ftrace_return. To disable
* the call to prepare_ftrace_return we patch the bras offset to point
* directly after the instructions. To enable the call we calculate
* the original offset to prepare_ftrace_return and put it back.
*/
int ftrace_enable_ftrace_graph_caller(void)
{
unsigned short offset;
offset = ((void *) prepare_ftrace_return -
(void *) ftrace_graph_caller) / 2;
return probe_kernel_write(ftrace_graph_caller + 2,
&offset, sizeof(offset));
}
int ftrace_disable_ftrace_graph_caller(void)
{
static unsigned short offset = 0x0002;
return probe_kernel_write(ftrace_graph_caller + 2,
&offset, sizeof(offset));
}
#endif /* CONFIG_DYNAMIC_FTRACE */
#endif /* CONFIG_FUNCTION_GRAPH_TRACER */

30
arch/s390/kernel/mcount.S
View File

@ -18,22 +18,12 @@ _mcount:
#ifdef CONFIG_DYNAMIC_FTRACE
br %r14
.data
.globl ftrace_dyn_func
ftrace_dyn_func:
.long ftrace_stub
.previous
.globl ftrace_caller
ftrace_caller:
#endif
stm %r2,%r5,16(%r15)
bras %r1,2f
#ifdef CONFIG_DYNAMIC_FTRACE
0: .long ftrace_dyn_func
#else
0: .long ftrace_trace_function
#endif
1: .long function_trace_stop
2: l %r2,1b-0b(%r1)
icm %r2,0xf,0(%r2)
@ -49,21 +39,15 @@ ftrace_caller:
l %r14,0(%r14)
basr %r14,%r14
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
l %r2,100(%r15)
l %r3,152(%r15)
.globl ftrace_graph_caller
ftrace_graph_caller:
# This unconditional branch gets runtime patched. Change only if
# you know what you are doing. See ftrace_enable_graph_caller().
j 1f
#endif
bras %r1,0f
.long prepare_ftrace_return
0: l %r2,152(%r15)
l %r4,0(%r1)
l %r3,100(%r15)
basr %r14,%r4
st %r2,100(%r15)
1:
# The bras instruction gets runtime patched to call prepare_ftrace_return.
# See ftrace_enable_ftrace_graph_caller. The patched instruction is:
# bras %r14,prepare_ftrace_return
bras %r14,0f
0: st %r2,100(%r15)
#endif
ahi %r15,96
l %r14,56(%r15)

27
arch/s390/kernel/mcount64.S
View File

@ -18,12 +18,6 @@ _mcount:
#ifdef CONFIG_DYNAMIC_FTRACE
br %r14
.data
.globl ftrace_dyn_func
ftrace_dyn_func:
.quad ftrace_stub
.previous
.globl ftrace_caller
ftrace_caller:
#endif
@ -37,26 +31,19 @@ ftrace_caller:
stg %r1,__SF_BACKCHAIN(%r15)
lgr %r2,%r14
lg %r3,168(%r15)
#ifdef CONFIG_DYNAMIC_FTRACE
larl %r14,ftrace_dyn_func
#else
larl %r14,ftrace_trace_function
#endif
lg %r14,0(%r14)
basr %r14,%r14
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
lg %r2,168(%r15)
lg %r3,272(%r15)
.globl ftrace_graph_caller
ftrace_graph_caller:
# This unconditional branch gets runtime patched. Change only if
# you know what you are doing. See ftrace_enable_graph_caller().
j 0f
#endif
lg %r2,272(%r15)
lg %r3,168(%r15)
brasl %r14,prepare_ftrace_return
stg %r2,168(%r15)
0:
# The bras instruction gets runtime patched to call prepare_ftrace_return.
# See ftrace_enable_ftrace_graph_caller. The patched instruction is:
# bras %r14,prepare_ftrace_return
bras %r14,0f
0: stg %r2,168(%r15)
#endif
aghi %r15,160
lmg %r2,%r5,32(%r15)