From ee456bb346e75a9b6d941224b108250e6ee5f79f Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 26 Apr 2012 08:31:17 +0000 Subject: powerpc/ftrace: Have PPC skip updating with stop_machine() PowerPC does not have the synchronization issues that x86 has with modifying code on one CPU while another CPU is executing it. The other CPU will either see the old or new code without any issues, unlike x86 which may issue a GPF. Instead of calling the heavy stop_machine, just update the code. Signed-off-by: Steven Rostedt Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/ftrace.c | 52 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) (limited to 'arch/powerpc/kernel/ftrace.c') diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index bf99cfa6bbf..d56848afd2c 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -484,6 +484,58 @@ int ftrace_update_ftrace_func(ftrace_func_t func) return ret; } +static int __ftrace_replace_code(struct dyn_ftrace *rec, int enable) +{ + unsigned long ftrace_addr = (unsigned long)FTRACE_ADDR; + int ret; + + ret = ftrace_update_record(rec, enable); + + switch (ret) { + case FTRACE_UPDATE_IGNORE: + return 0; + case FTRACE_UPDATE_MAKE_CALL: + return ftrace_make_call(rec, ftrace_addr); + case FTRACE_UPDATE_MAKE_NOP: + return ftrace_make_nop(NULL, rec, ftrace_addr); + } + + return 0; +} + +void ftrace_replace_code(int enable) +{ + struct ftrace_rec_iter *iter; + struct dyn_ftrace *rec; + int ret; + + for (iter = ftrace_rec_iter_start(); iter; + iter = ftrace_rec_iter_next(iter)) { + rec = ftrace_rec_iter_record(iter); + ret = __ftrace_replace_code(rec, enable); + if (ret) { + ftrace_bug(ret, rec->ip); + return; + } + } +} + +void arch_ftrace_update_code(int command) +{ + if (command & FTRACE_UPDATE_CALLS) + ftrace_replace_code(1); + else if (command & FTRACE_DISABLE_CALLS) + ftrace_replace_code(0); + + if (command & FTRACE_UPDATE_TRACE_FUNC) + ftrace_update_ftrace_func(ftrace_trace_function); + + if (command & FTRACE_START_FUNC_RET) + ftrace_enable_ftrace_graph_caller(); + else if (command & FTRACE_STOP_FUNC_RET) + ftrace_disable_ftrace_graph_caller(); +} + int __init ftrace_dyn_arch_init(void *data) { /* caller expects data to be zero */ -- cgit v1.2.3-70-g09d2 From 65b8c7226eb74a7db1a618d69d5cb0cb5f13e99d Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 26 Apr 2012 08:31:19 +0000 Subject: powerpc/ftrace: Use patch_instruction instead of probe_kernel_write() The patch_instruction() interface is made to modify kernel text. It is safer to use that then the probe_kernel_write() when modifying kernel code. Signed-off-by: Steven Rostedt Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/ftrace.c | 17 ++++------------- 1 file changed, 4 insertions(+), 13 deletions(-) (limited to 'arch/powerpc/kernel/ftrace.c') diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index d56848afd2c..6f33296a057 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -63,11 +63,9 @@ ftrace_modify_code(unsigned long ip, unsigned int old, unsigned int new) return -EINVAL; /* replace the text with the new text */ - if (probe_kernel_write((void *)ip, &new, MCOUNT_INSN_SIZE)) + if (patch_instruction((unsigned int *)ip, new)) return -EPERM; - flush_icache_range(ip, ip + 8); - return 0; } @@ -212,12 +210,9 @@ __ftrace_make_nop(struct module *mod, */ op = 0x48000008; /* b +8 */ - if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) + if (patch_instruction((unsigned int *)ip, op)) return -EPERM; - - flush_icache_range(ip, ip + 8); - return 0; } @@ -286,11 +281,9 @@ __ftrace_make_nop(struct module *mod, op = PPC_INST_NOP; - if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) + if (patch_instruction((unsigned int *)ip, op)) return -EPERM; - flush_icache_range(ip, ip + 8); - return 0; } #endif /* PPC64 */ @@ -426,11 +419,9 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) pr_devel("write to %lx\n", rec->ip); - if (probe_kernel_write((void *)ip, &op, MCOUNT_INSN_SIZE)) + if (patch_instruction((unsigned int *)ip, op)) return -EPERM; - flush_icache_range(ip, ip + 8); - return 0; } #endif /* CONFIG_PPC64 */ -- cgit v1.2.3-70-g09d2 From fd5a42980e1cf327b7240adf5e7b51ea41c23437 Mon Sep 17 00:00:00 2001 From: roger blofeld Date: Thu, 21 Jun 2012 05:27:14 +0000 Subject: powerpc/ftrace: Fix assembly trampoline register usage Just like the module loader, ftrace needs to be updated to use r12 instead of r11 with newer gcc's. Signed-off-by: Roger Blofeld Signed-off-by: Benjamin Herrenschmidt CC: stable@vger.kernel.org --- arch/powerpc/kernel/ftrace.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'arch/powerpc/kernel/ftrace.c') diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 6f33296a057..91b46b7f6f0 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -240,9 +240,9 @@ __ftrace_make_nop(struct module *mod, /* * On PPC32 the trampoline looks like: - * 0x3d, 0x60, 0x00, 0x00 lis r11,sym@ha - * 0x39, 0x6b, 0x00, 0x00 addi r11,r11,sym@l - * 0x7d, 0x69, 0x03, 0xa6 mtctr r11 + * 0x3d, 0x80, 0x00, 0x00 lis r12,sym@ha + * 0x39, 0x8c, 0x00, 0x00 addi r12,r12,sym@l + * 0x7d, 0x89, 0x03, 0xa6 mtctr r12 * 0x4e, 0x80, 0x04, 0x20 bctr */ @@ -257,9 +257,9 @@ __ftrace_make_nop(struct module *mod, pr_devel(" %08x %08x ", jmp[0], jmp[1]); /* verify that this is what we expect it to be */ - if (((jmp[0] & 0xffff0000) != 0x3d600000) || - ((jmp[1] & 0xffff0000) != 0x396b0000) || - (jmp[2] != 0x7d6903a6) || + if (((jmp[0] & 0xffff0000) != 0x3d800000) || + ((jmp[1] & 0xffff0000) != 0x398c0000) || + (jmp[2] != 0x7d8903a6) || (jmp[3] != 0x4e800420)) { printk(KERN_ERR "Not a trampoline\n"); return -EINVAL; -- cgit v1.2.3-70-g09d2