arm64: ftrace: fix ftrace_modify_graph_caller for branch replace

ftrace_enable_ftrace_graph_caller and ftrace_disable_ftrace_graph_caller
should replace B(jmp) instruction and not BL(call) instruction.

Commit 9f1ae7596aad("arm64: Correct ftrace calls to
aarch64_insn_gen_branch_imm()") had a typo and used
AARCH64_INSN_BRANCH_LINK instead of AARCH64_INSN_BRANCH_NOLINK.

Either instruction will work, as the link register is saved/restored
across the branch but this better matches the intention of the code.

Signed-off-by: Pratyush Anand <panand@redhat.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index cf8556a..c851be7 100644 (file)
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -156,7 +156,7 @@ static int ftrace_modify_graph_caller(bool enable)
 
        branch = aarch64_insn_gen_branch_imm(pc,
                                             (unsigned long)ftrace_graph_caller,
-                                            AARCH64_INSN_BRANCH_LINK);
+                                            AARCH64_INSN_BRANCH_NOLINK);
        nop = aarch64_insn_gen_nop();
 
        if (enable)