diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2022-09-15 13:11:37 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-17 16:41:19 +0200 |
| commit | ee3e2469b3463d28ca4cde20e0283319ac6a562d (patch) | |
| tree | 958265de2b1865d821630bc175df913052ac7f25 /arch/x86/net/bpf_jit_comp.c | |
| parent | 36b64f101219dd9e6e4f0ea880b64e8a90da547b (diff) | |
x86/ftrace: Make it call depth tracking aware
Since ftrace has trampolines, don't use thunks for the __fentry__ site
but instead require that every function called from there includes
accounting. This very much includes all the direct-call functions.
Additionally, ftrace uses ROP tricks in two places:
- return_to_handler(), and
- ftrace_regs_caller() when pt_regs->orig_ax is set by a direct-call.
return_to_handler() already uses a retpoline to replace an
indirect-jump to defeat IBT, since this is a jump-type retpoline, make
sure there is no accounting done and ALTERNATIVE the RET into a ret.
ftrace_regs_caller() does much the same and gets the same treatment.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111148.927545073@infradead.org
Diffstat (limited to 'arch/x86/net/bpf_jit_comp.c')
| -rw-r--r-- | arch/x86/net/bpf_jit_comp.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index a6b46740ea30..f46b62029d91 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -12,6 +12,7 @@ #include <linux/memory.h> #include <linux/sort.h> #include <asm/extable.h> +#include <asm/ftrace.h> #include <asm/set_memory.h> #include <asm/nospec-branch.h> #include <asm/text-patching.h> @@ -2135,6 +2136,11 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i prog = image; EMIT_ENDBR(); + /* + * This is the direct-call trampoline, as such it needs accounting + * for the __fentry__ call. + */ + x86_call_depth_emit_accounting(&prog, NULL); EMIT1(0x55); /* push rbp */ EMIT3(0x48, 0x89, 0xE5); /* mov rbp, rsp */ EMIT4(0x48, 0x83, 0xEC, stack_size); /* sub rsp, stack_size */ |