diff options
| -rw-r--r-- | arch/x86/lib/retpoline.S | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index d410abacbf88..a48077c5ca61 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -129,6 +129,13 @@ SYM_CODE_END(__x86_indirect_jump_thunk_array) #ifdef CONFIG_RETHUNK +/* + * Be careful here: that label cannot really be removed because in + * some configurations and toolchains, the JMP __x86_return_thunk the + * compiler issues is either a short one or the compiler doesn't use + * relocations for same-section JMPs and that breaks the returns + * detection logic in apply_returns() and in objtool. + */ .section .text..__x86.return_thunk #ifdef CONFIG_CPU_SRSO @@ -361,6 +368,14 @@ SYM_FUNC_END(call_depth_return_thunk) * This code is only used during kernel boot or module init. All * 'JMP __x86_return_thunk' sites are changed to something else by * apply_returns(). + * + * This should be converted eventually to call a warning function which + * should scream loudly when the default return thunk is called after + * alternatives have been applied. + * + * That warning function cannot BUG() because the bug splat cannot be + * displayed in all possible configurations, leading to users not really + * knowing why the machine froze. */ SYM_CODE_START(__x86_return_thunk) UNWIND_HINT_FUNC |