From mboxrd@z Thu Jan 1 00:00:00 1970 From: rabin@rab.in (Rabin Vincent) Date: Wed, 22 Feb 2012 19:43:17 +0530 Subject: [PATCHv2 1/6] ARM: ftrace: remove useless memory checks In-Reply-To: <20120220161601.GH26840@n2100.arm.linux.org.uk> References: <1327757725-10114-1-git-send-email-rabin@rab.in> <1327757725-10114-2-git-send-email-rabin@rab.in> <20120220161601.GH26840@n2100.arm.linux.org.uk> Message-ID: <20120222141317.GB9031@debian> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Feb 20, 2012 at 04:16:01PM +0000, Russell King - ARM Linux wrote: > On Sat, Jan 28, 2012 at 07:05:20PM +0530, Rabin Vincent wrote: > > diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c > > index c0062ad..e9488ad 100644 > > --- a/arch/arm/kernel/ftrace.c > > +++ b/arch/arm/kernel/ftrace.c > > @@ -125,11 +125,13 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old, > > { > > unsigned long replaced; > > > > - if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE)) > > - return -EFAULT; > > + if (old) { > > So, we're using the instruction value '0' to mean that we don't want to > check? Wouldn'it it be better to pass a flag in to indicate this instead > of creating a magic value? OK. I think you applied this patch as-is anyway, so here is a follow-on patch: 8<------------ >>From 18ad9e696a3b3986babb1c91807d3f39d6468176 Mon Sep 17 00:00:00 2001 From: Rabin Vincent Date: Wed, 22 Feb 2012 19:11:46 +0530 Subject: [PATCH] ARM: ftrace: use flag for memory check We currently use a (magic) value of 0 for the old instruction value to detect if we should verify the old value in memory or not. Pass a flag instead. Signed-off-by: Rabin Vincent --- arch/arm/kernel/ftrace.c | 16 ++++++++-------- 1 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 858c63f..df0bf0c 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -69,7 +69,7 @@ static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) } static int ftrace_modify_code(unsigned long pc, unsigned long old, - unsigned long new) + unsigned long new, bool validate) { unsigned long replaced; @@ -81,7 +81,7 @@ static int ftrace_modify_code(unsigned long pc, unsigned long old, new = __opcode_to_mem_arm(new); } - if (old) { + if (validate) { if (probe_kernel_read(&replaced, (void *)pc, MCOUNT_INSN_SIZE)) return -EFAULT; @@ -106,14 +106,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func) pc = (unsigned long)&ftrace_call; new = ftrace_call_replace(pc, (unsigned long)func); - ret = ftrace_modify_code(pc, 0, new); + ret = ftrace_modify_code(pc, 0, new, false); #ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; new = ftrace_call_replace(pc, (unsigned long)func); - ret = ftrace_modify_code(pc, 0, new); + ret = ftrace_modify_code(pc, 0, new, false); } #endif @@ -128,7 +128,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) old = ftrace_nop_replace(rec); new = ftrace_call_replace(ip, adjust_address(rec, addr)); - return ftrace_modify_code(rec->ip, old, new); + return ftrace_modify_code(rec->ip, old, new, true); } int ftrace_make_nop(struct module *mod, @@ -141,7 +141,7 @@ int ftrace_make_nop(struct module *mod, old = ftrace_call_replace(ip, adjust_address(rec, addr)); new = ftrace_nop_replace(rec); - ret = ftrace_modify_code(ip, old, new); + ret = ftrace_modify_code(ip, old, new, true); #ifdef CONFIG_OLD_MCOUNT if (ret == -EINVAL && addr == MCOUNT_ADDR) { @@ -149,7 +149,7 @@ int ftrace_make_nop(struct module *mod, old = ftrace_call_replace(ip, adjust_address(rec, addr)); new = ftrace_nop_replace(rec); - ret = ftrace_modify_code(ip, old, new); + ret = ftrace_modify_code(ip, old, new, true); } #endif @@ -210,7 +210,7 @@ static int __ftrace_modify_caller(unsigned long *callsite, unsigned long old = enable ? nop : branch; unsigned long new = enable ? branch : nop; - return ftrace_modify_code(pc, old, new); + return ftrace_modify_code(pc, old, new, true); } static int ftrace_modify_graph_caller(bool enable) -- 1.7.9