From b54dcfe108b1b72c9d891dce1034aa5679c0d7db Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 13 Feb 2009 06:31:39 -0800 Subject: [PATCH] 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 Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/ftrace.c | 45 +++++++++++++++--------------------- 1 file changed, 18 insertions(+), 27 deletions(-) diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index dddd99bbbd8d..610c852b92ed 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 @@ 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); -- 2.20.1