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| author | Peter Zijlstra <peterz@infradead.org> | 2022-09-15 13:11:36 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-10-17 16:41:19 +0200 |
| commit | 36b64f101219dd9e6e4f0ea880b64e8a90da547b (patch) | |
| tree | e3ffe8cca7a7d2946a904fa0b5f87576a1ffcd0a | |
| parent | x86/ftrace: Remove ftrace_epilogue() (diff) | |
| download | linux-36b64f101219dd9e6e4f0ea880b64e8a90da547b.tar.xz linux-36b64f101219dd9e6e4f0ea880b64e8a90da547b.zip | |
x86/ftrace: Rebalance RSB
ftrace_regs_caller() uses a PUSH;RET pattern to tail-call into a
direct-call function, this unbalances the RSB, fix that.
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/20220915111148.823216933@infradead.org
| -rw-r--r-- | arch/x86/kernel/ftrace_64.S | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S index a90c55a6b481..b5b54f58957e 100644 --- a/arch/x86/kernel/ftrace_64.S +++ b/arch/x86/kernel/ftrace_64.S @@ -271,6 +271,17 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL) /* Restore flags */ popfq UNWIND_HINT_FUNC + + /* + * The above left an extra return value on the stack; effectively + * doing a tail-call without using a register. This PUSH;RET + * pattern unbalances the RSB, inject a pointless CALL to rebalance. + */ + ANNOTATE_INTRA_FUNCTION_CALL + CALL .Ldo_rebalance + int3 +.Ldo_rebalance: + add $8, %rsp RET SYM_FUNC_END(ftrace_regs_caller) |