Use create_branch() rather than doing it by hand. It's possible that
we are unable to create a branch to the address, if it's too far away,
in which case just return a nop. This will break the tracing, but
shouldn't crash the kernel at least.
Signed-off-by: Michael Ellerman <[EMAIL PROTECTED]>
---
arch/powerpc/kernel/ftrace.c | 20 ++++++++------------
1 files changed, 8 insertions(+), 12 deletions(-)
diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c
index 1d6f174..49a2049 100644
--- a/arch/powerpc/kernel/ftrace.c
+++ b/arch/powerpc/kernel/ftrace.c
@@ -19,11 +19,6 @@
#include <asm/ftrace.h>
-static unsigned int notrace ftrace_calc_offset(long ip, long addr)
-{
- return (int)(addr - ip);
-}
-
notrace unsigned char *ftrace_nop_replace(void)
{
static unsigned int ftrace_nop = PPC_NOP_INSTR;
@@ -35,16 +30,17 @@ 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 = ppc_function_entry((void *)addr);
/* Set to "bl addr" */
- op = 0x48000001 | (ftrace_calc_offset(ip, addr) & 0x03fffffc);
+ op = create_branch((unsigned int *)ip, addr, BRANCH_SET_LINK);
+
+ /*
+ * This routine is not allowed to fail, but create_branch() can.
+ * In that case, just return nop and cross our fingers.
+ */
+ if (!op)
+ return ftrace_nop_replace();
/*
* No locking needed, this must be called via kstop_machine
--
1.5.5
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