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/kernel/callthunks.c | |
| parent | x86/ftrace: Rebalance RSB (diff) | |
| download | linux-ee3e2469b3463d28ca4cde20e0283319ac6a562d.tar.xz linux-ee3e2469b3463d28ca4cde20e0283319ac6a562d.zip | |
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/kernel/callthunks.c')
| -rw-r--r-- | arch/x86/kernel/callthunks.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index a03d646b5e69..7d2c75ec9a8c 100644 --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -316,7 +316,7 @@ int x86_call_depth_emit_accounting(u8 **pprog, void *func) return 0; /* Is function call target a thunk? */ - if (is_callthunk(func)) + if (func && is_callthunk(func)) return 0; memcpy(*pprog, tmpl, tmpl_size); |