[tip:perf/core] ftrace/x86-64: Allow to change RIP in handlers

[tip-bot for Steven Rostedt]

Commit-ID:  47d5a5f88b9d25d6464c9b60c28f391e84e3ed65
Gitweb:     http://git.kernel.org/tip/47d5a5f88b9d25d6464c9b60c28f391e84e3ed65
Author:     Steven Rostedt <rostedt@xxxxxxxxxxx>
AuthorDate: Wed, 5 Sep 2012 23:31:18 +0900
Committer:  Steven Rostedt <rostedt@xxxxxxxxxxx>
CommitDate: Thu, 13 Sep 2012 22:52:10 -0400

ftrace/x86-64: Allow to change RIP in handlers

Allow ftrace handlers to change RIP register (regs->ip)
in handlers. This will allow handlers to call another
function instead of original function.

Link: http://lkml.kernel.org/r/20120905143118.10329.5078.stgit@xxxxxxxxxxxxxxxxxxxxx

Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 arch/x86/kernel/entry_64.S |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index ed767b7..e9cc2b3 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -165,6 +165,10 @@ GLOBAL(ftrace_regs_call)
 	movq EFLAGS(%rsp), %rax
 	movq %rax, SS(%rsp)
 
+	/* Handlers can change the RIP */
+	movq RIP(%rsp), %rax
+	movq %rax, SS+8(%rsp)
+
 	/* restore the rest of pt_regs */
 	movq R15(%rsp), %r15
 	movq R14(%rsp), %r14
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/