From mboxrd@z Thu Jan 1 00:00:00 1970 From: abelvesa@linux.com (Abel Vesa) Date: Tue, 6 Dec 2016 17:06:02 +0000 Subject: [PATCH 2/7] arm: ftrace: Add call modify mechanism In-Reply-To: <1481043967-15602-1-git-send-email-abelvesa@linux.com> References: <1481043967-15602-1-git-send-email-abelvesa@linux.com> Message-ID: <1481043967-15602-3-git-send-email-abelvesa@linux.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Function ftrace_modify_call provides a way to replace ftrace_stub with the ftrace function. This helps the klp_ftrace_handler to be called via ftrace_ops_no_ops, which in turn will set the pc with the patched function's starting address. This is used for livepatching. Signed-off-by: Abel Vesa --- arch/arm/kernel/ftrace.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 3f17594..cb4543a 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -139,6 +139,15 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ret = ftrace_modify_code(pc, 0, new, false); +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + if (!ret) { + pc = (unsigned long)&ftrace_regs_call; + new = ftrace_call_replace(pc, (unsigned long)func); + + ret = ftrace_modify_code(pc, 0, new, false); + } +#endif + #ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; @@ -151,6 +160,18 @@ int ftrace_update_ftrace_func(ftrace_func_t func) return ret; } +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, + unsigned long addr) +{ + unsigned long pc = rec->ip; + u32 old, new; + + old = arm_gen_branch(pc, old_addr); + new = arm_gen_branch(pc, addr); + + return ftrace_modify_code(pc, old, new, true); +} + int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned long new, old; -- 2.7.4