From: Thadeu Lima de Souza Cascardo cascardo@canonical.com
This reverts commit 00b136bb6254e0abf6aaafe62c4da5f6c4fea4cb.
This temporarily reverts the backport of upstream commit 1f001e9da6bbf482311e45e48f53c2bd2179e59c. It was not correct to copy the ftrace stub as it would contain a relative jump to the return thunk which would not apply to the context where it was being copied to, leading to ftrace support to be broken.
Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com --- This series fixes the CONFIG_KPROBES_SANITY_TEST=y boot panic reported here: https://lore.kernel.org/stable/20220805200438.GC42579@windriver.com/
The fixes were backported from v5.15.62. Minor contextual adjustments were made in arch/x86/kernel/ftrace_64.S for the backport of e52fc2cf3f66 ("x86/ibt,ftrace: Make function-graph play nice").
arch/x86/kernel/ftrace.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index 9a8633a6506c..449e31a2f124 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -309,7 +309,7 @@ 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) @@ -368,10 +368,7 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
/* The trampoline ends with ret(q) */ retq = (unsigned long)ftrace_stub; - if (cpu_feature_enabled(X86_FEATURE_RETHUNK)) - memcpy(ip, text_gen_insn(JMP32_INSN_OPCODE, ip, &__x86_return_thunk), JMP32_INSN_SIZE); - else - ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE); + ret = copy_from_kernel_nofault(ip, (void *)retq, RET_SIZE); if (WARN_ON(ret < 0)) goto fail;