powerpc, ftrace: use unsigned int for instruction manipulation
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>
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index dddd99b..610c852 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -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 @@
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 @@
#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 @@
*/
/* 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 @@
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 @@
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_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 @@
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 @@
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);
