[PATCH v2 04/25] powerpc/ftrace: Use is_offset_in_branch_range()

From: Christophe Leroy
Date: Sat May 07 2022 - 02:48:18 EST


Use is_offset_in_branch_range() instead of create_branch()
to check if a target is within branch range.

This patch together with the previous one improves
ftrace activation time by 7%

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
arch/powerpc/kernel/trace/ftrace.c | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c
index 3ce3697e8a7c..41c45b9c7f39 100644
--- a/arch/powerpc/kernel/trace/ftrace.c
+++ b/arch/powerpc/kernel/trace/ftrace.c
@@ -89,11 +89,9 @@ ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new)
*/
static int test_24bit_addr(unsigned long ip, unsigned long addr)
{
- ppc_inst_t op;
addr = ppc_function_entry((void *)addr);

- /* use the create_branch to verify that this offset can be branched */
- return create_branch(&op, (u32 *)ip, addr, 0) == 0;
+ return is_offset_in_branch_range(addr - ip);
}

static int is_bl_op(ppc_inst_t op)
@@ -261,7 +259,6 @@ __ftrace_make_nop(struct module *mod,
static unsigned long find_ftrace_tramp(unsigned long ip)
{
int i;
- ppc_inst_t instr;

/*
* We have the compiler generated long_branch tramps at the end
@@ -270,8 +267,7 @@ static unsigned long find_ftrace_tramp(unsigned long ip)
for (i = NUM_FTRACE_TRAMPS - 1; i >= 0; i--)
if (!ftrace_tramps[i])
continue;
- else if (create_branch(&instr, (void *)ip,
- ftrace_tramps[i], 0) == 0)
+ else if (is_offset_in_branch_range(ftrace_tramps[i] - ip))
return ftrace_tramps[i];

return 0;
--
2.35.1