Revert "x86/ftrace: Use alternative RET encoding"

This reverts commit 3eb602ad6a94a76941f93173131a71ad36fa1324.

Revert the backport of upstream commit

  1f001e9da6bb ("x86/ftrace: Use alternative RET encoding")

in favor of a proper backport after backporting the commit which adds
__text_gen_insn().

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 6d546f4426ac3e969099f212b81e6a1088d16edc..dd160160c1db8c167df7fd336da2052c584ce6a1 100644 (file)
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -311,7 +311,7 @@ union ftrace_op_code_union {
        } __attribute__((packed));
 };
 
-#define RET_SIZE               (IS_ENABLED(CONFIG_RETPOLINE) ? 5 : 1 + IS_ENABLED(CONFIG_SLS))
+#define RET_SIZE               1 + IS_ENABLED(CONFIG_SLS)
 
 static unsigned long
 create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
@@ -367,12 +367,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
                goto fail;
 
        ip = trampoline + size;
-
-       /* The trampoline ends with ret(q) */
-       if (cpu_feature_enabled(X86_FEATURE_RETHUNK))
-               memcpy(ip, text_gen_insn(JMP32_INSN_OPCODE, ip, &__x86_return_thunk), JMP32_INSN_SIZE);
-       else
-               memcpy(ip, retq, sizeof(retq));
+       memcpy(ip, retq, RET_SIZE);
 
        /* No need to test direct calls on created trampolines */
        if (ops->flags & FTRACE_OPS_FL_SAVE_REGS) {