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powerpc, ftrace: use unsigned int for instruction manipulation

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The original port of ftrace to PowerPC kept a lot of the code used
by x86. Some of this code was to handle x86's 5 byte instruction.
This was handled by using character arrays to manipulate the
code.

PowerPC has a consistent 4 byte instruction. Using unsigned ints
makes the code more efficient as well as more readable.
By converting to use unsigned ints to represent instructions,
I was able to remove the side effects that were needed for
manipulating character strings.

  i.e. memcpy and memcmp

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Steven Rostedt 2009-02-13 06:31:39 -08:00 committed by Benjamin Herrenschmidt
parent 60ce8f7260
commit b54dcfe108
1 changed files with 18 additions and 27 deletions
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45
arch/powerpc/kernel/ftrace.c
View file

@ -31,22 +31,20 @@
#endif
#ifdef CONFIG_DYNAMIC_FTRACE
static unsigned int ftrace_nop = PPC_NOP_INSTR;
static unsigned int ftrace_calc_offset(long ip, long addr)
{
return (int)(addr - ip);
}
static unsigned char *ftrace_nop_replace(void)
static unsigned int ftrace_nop_replace(void)
{
return (char *)&ftrace_nop;
return PPC_NOP_INSTR;
}
static unsigned char *
static unsigned int
ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
{
static unsigned int op;
unsigned int op;
/*
* It would be nice to just use create_function_call, but that will
@ -60,11 +58,7 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
op = 0x48000000 | (link ? 1 : 0);
op |= (ftrace_calc_offset(ip, addr) & 0x03fffffc);
/*
* No locking needed, this must be called via kstop_machine
* which in essence is like running on a uniprocessor machine.
*/
return (unsigned char *)&op;
return op;
}
#ifdef CONFIG_PPC64
@ -76,10 +70,9 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link)
#endif
static int
ftrace_modify_code(unsigned long ip, unsigned char *old_code,
unsigned char *new_code)
ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new)
{
unsigned char replaced[MCOUNT_INSN_SIZE];
unsigned int replaced;
/*
* Note: Due to modules and __init, code can
@ -92,15 +85,15 @@ ftrace_modify_code(unsigned long ip, unsigned char *old_code,
*/
/* read the text we want to modify */
if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
if (probe_kernel_read(&replaced, (void *)ip, MCOUNT_INSN_SIZE))
return -EFAULT;
/* Make sure it is what we expect it to be */
if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
if (replaced != old)
return -EINVAL;
/* replace the text with the new text */
if (probe_kernel_write((void *)ip, new_code, MCOUNT_INSN_SIZE))
if (probe_kernel_write((void *)ip, &new, MCOUNT_INSN_SIZE))
return -EPERM;
flush_icache_range(ip, ip + 8);
@ -336,8 +329,8 @@ __ftrace_make_nop(struct module *mod,
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
unsigned char *old, *new;
unsigned long ip = rec->ip;
unsigned int old, new;
/*
* If the calling address is more that 24 bits away,
@ -475,8 +468,8 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned char *old, *new;
unsigned long ip = rec->ip;
unsigned int old, new;
/*
* If the calling address is more that 24 bits away,
@ -511,10 +504,10 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
int ftrace_update_ftrace_func(ftrace_func_t func)
{
unsigned long ip = (unsigned long)(&ftrace_call);
unsigned char old[MCOUNT_INSN_SIZE], *new;
unsigned int old, new;
int ret;
memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE);
old = *(unsigned int *)&ftrace_call;
new = ftrace_call_replace(ip, (unsigned long)func, 1);
ret = ftrace_modify_code(ip, old, new);
@ -543,10 +536,9 @@ int ftrace_enable_ftrace_graph_caller(void)
unsigned long ip = (unsigned long)(&ftrace_graph_call);
unsigned long addr = (unsigned long)(&ftrace_graph_caller);
unsigned long stub = (unsigned long)(&ftrace_graph_stub);
unsigned char old[MCOUNT_INSN_SIZE], *new;
unsigned int old, new;
new = ftrace_call_replace(ip, stub, 0);
memcpy(old, new, MCOUNT_INSN_SIZE);
old = ftrace_call_replace(ip, stub, 0);
new = ftrace_call_replace(ip, addr, 0);
return ftrace_modify_code(ip, old, new);
@ -557,10 +549,9 @@ int ftrace_disable_ftrace_graph_caller(void)
unsigned long ip = (unsigned long)(&ftrace_graph_call);
unsigned long addr = (unsigned long)(&ftrace_graph_caller);
unsigned long stub = (unsigned long)(&ftrace_graph_stub);
unsigned char old[MCOUNT_INSN_SIZE], *new;
unsigned int old, new;
new = ftrace_call_replace(ip, addr, 0);
memcpy(old, new, MCOUNT_INSN_SIZE);
old = ftrace_call_replace(ip, addr, 0);
new = ftrace_call_replace(ip, stub, 0);
return ftrace_modify_code(ip, old, new);