diff options
author | Ingo Molnar <mingo@elte.hu> | 2008-07-10 11:43:00 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2008-07-10 11:43:00 +0200 |
commit | bac0c9103b31c3dd83ad9d731dd9834e2ba75e4f (patch) | |
tree | 702dd6a7ce06d224d594c2293af546b11ac9f51b /arch/powerpc/kernel/ftrace.c | |
parent | 6329d3021bcfa9038621e6e917d98929421d8ec8 (diff) | |
parent | 98a05ed4bd7774f533ab185fe0bf2fdc58292d7c (diff) |
Merge branch 'tracing/ftrace' into auto-ftrace-next
Diffstat (limited to 'arch/powerpc/kernel/ftrace.c')
-rw-r--r-- | arch/powerpc/kernel/ftrace.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c new file mode 100644 index 00000000000..3855ceb937b --- /dev/null +++ b/arch/powerpc/kernel/ftrace.c @@ -0,0 +1,154 @@ +/* + * Code for replacing ftrace calls with jumps. + * + * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> + * + * Thanks goes out to P.A. Semi, Inc for supplying me with a PPC64 box. + * + */ + +#include <linux/spinlock.h> +#include <linux/hardirq.h> +#include <linux/ftrace.h> +#include <linux/percpu.h> +#include <linux/init.h> +#include <linux/list.h> + +#include <asm/cacheflush.h> +#include <asm/ftrace.h> + + +static unsigned int ftrace_nop = 0x60000000; + +#ifdef CONFIG_PPC32 +# define GET_ADDR(addr) addr +#else +/* PowerPC64's functions are data that points to the functions */ +# define GET_ADDR(addr) *(unsigned long *)addr +#endif + + +static unsigned int notrace ftrace_calc_offset(long ip, long addr) +{ + return (int)(addr - ip); +} + +notrace unsigned char *ftrace_nop_replace(void) +{ + return (char *)&ftrace_nop; +} + +notrace unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr) +{ + static unsigned int op; + + /* + * It would be nice to just use create_function_call, but that will + * update the code itself. Here we need to just return the + * instruction that is going to be modified, without modifying the + * code. + */ + addr = GET_ADDR(addr); + + /* Set to "bl addr" */ + op = 0x48000001 | (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; +} + +#ifdef CONFIG_PPC64 +# define _ASM_ALIGN " .align 3 " +# define _ASM_PTR " .llong " +#else +# define _ASM_ALIGN " .align 2 " +# define _ASM_PTR " .long " +#endif + +notrace int +ftrace_modify_code(unsigned long ip, unsigned char *old_code, + unsigned char *new_code) +{ + unsigned replaced; + unsigned old = *(unsigned *)old_code; + unsigned new = *(unsigned *)new_code; + int faulted = 0; + + /* + * Note: Due to modules and __init, code can + * disappear and change, we need to protect against faulting + * as well as code changing. + * + * No real locking needed, this code is run through + * kstop_machine. + */ + asm volatile ( + "1: lwz %1, 0(%2)\n" + " cmpw %1, %5\n" + " bne 2f\n" + " stwu %3, 0(%2)\n" + "2:\n" + ".section .fixup, \"ax\"\n" + "3: li %0, 1\n" + " b 2b\n" + ".previous\n" + ".section __ex_table,\"a\"\n" + _ASM_ALIGN "\n" + _ASM_PTR "1b, 3b\n" + ".previous" + : "=r"(faulted), "=r"(replaced) + : "r"(ip), "r"(new), + "0"(faulted), "r"(old) + : "memory"); + + if (replaced != old && replaced != new) + faulted = 2; + + if (!faulted) + flush_icache_range(ip, ip + 8); + + return faulted; +} + +notrace int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned long ip = (unsigned long)(&ftrace_call); + unsigned char old[MCOUNT_INSN_SIZE], *new; + int ret; + + memcpy(old, &ftrace_call, MCOUNT_INSN_SIZE); + new = ftrace_call_replace(ip, (unsigned long)func); + ret = ftrace_modify_code(ip, old, new); + + return ret; +} + +notrace int ftrace_mcount_set(unsigned long *data) +{ + unsigned long ip = (long)(&mcount_call); + unsigned long *addr = data; + unsigned char old[MCOUNT_INSN_SIZE], *new; + + /* + * Replace the mcount stub with a pointer to the + * ip recorder function. + */ + memcpy(old, &mcount_call, MCOUNT_INSN_SIZE); + new = ftrace_call_replace(ip, *addr); + *addr = ftrace_modify_code(ip, old, new); + + return 0; +} + +int __init ftrace_dyn_arch_init(void *data) +{ + /* This is running in kstop_machine */ + + ftrace_mcount_set(data); + + return 0; +} + |