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Commit b54dcfe1 authored by Steven Rostedt's avatar Steven Rostedt Committed by Benjamin Herrenschmidt
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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: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 60ce8f72

arch/powerpc/kernel/ftrace.c

+18 −27
Original line number Diff line number Diff line
@@ -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);