5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Peter Zijlstra <peterz@xxxxxxxxxxxxx> commit d025b7bac07a6e90b6b98b487f88854ad9247c39 upstream. Rename the original retbleed return thunk and untrain_ret to retbleed_return_thunk() and retbleed_untrain_ret(). No functional changes. Suggested-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx> Link: https://lore.kernel.org/r/20230814121148.909378169@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/include/asm/nospec-branch.h | 8 ++++---- arch/x86/kernel/cpu/bugs.c | 2 +- arch/x86/kernel/vmlinux.lds.S | 2 +- arch/x86/lib/retpoline.S | 30 +++++++++++++++--------------- tools/objtool/arch/x86/decode.c | 2 +- tools/objtool/check.c | 2 +- 6 files changed, 23 insertions(+), 23 deletions(-) --- a/arch/x86/include/asm/nospec-branch.h +++ b/arch/x86/include/asm/nospec-branch.h @@ -156,7 +156,7 @@ .endm #ifdef CONFIG_CPU_UNRET_ENTRY -#define CALL_ZEN_UNTRAIN_RET "call zen_untrain_ret" +#define CALL_ZEN_UNTRAIN_RET "call retbleed_untrain_ret" #else #define CALL_ZEN_UNTRAIN_RET "" #endif @@ -166,7 +166,7 @@ * return thunk isn't mapped into the userspace tables (then again, AMD * typically has NO_MELTDOWN). * - * While zen_untrain_ret() doesn't clobber anything but requires stack, + * While retbleed_untrain_ret() doesn't clobber anything but requires stack, * entry_ibpb() will clobber AX, CX, DX. * * As such, this must be placed after every *SWITCH_TO_KERNEL_CR3 at a point @@ -201,11 +201,11 @@ extern void __x86_return_thunk(void); static inline void __x86_return_thunk(void) {} #endif -extern void zen_return_thunk(void); +extern void retbleed_return_thunk(void); extern void srso_return_thunk(void); extern void srso_alias_return_thunk(void); -extern void zen_untrain_ret(void); +extern void retbleed_untrain_ret(void); extern void srso_untrain_ret(void); extern void srso_untrain_ret_alias(void); --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -984,7 +984,7 @@ do_cmd_auto: setup_force_cpu_cap(X86_FEATURE_UNRET); if (IS_ENABLED(CONFIG_RETHUNK)) - x86_return_thunk = zen_return_thunk; + x86_return_thunk = retbleed_return_thunk; if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -518,7 +518,7 @@ INIT_PER_CPU(irq_stack_backing_store); #endif #ifdef CONFIG_RETHUNK -. = ASSERT((zen_return_thunk & 0x3f) == 0, "zen_return_thunk not cacheline-aligned"); +. = ASSERT((retbleed_return_thunk & 0x3f) == 0, "retbleed_return_thunk not cacheline-aligned"); . = ASSERT((srso_safe_ret & 0x3f) == 0, "srso_safe_ret not cacheline-aligned"); #endif --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -129,32 +129,32 @@ SYM_CODE_END(srso_alias_return_thunk) /* * Safety details here pertain to the AMD Zen{1,2} microarchitecture: - * 1) The RET at zen_return_thunk must be on a 64 byte boundary, for + * 1) The RET at retbleed_return_thunk must be on a 64 byte boundary, for * alignment within the BTB. - * 2) The instruction at zen_untrain_ret must contain, and not + * 2) The instruction at retbleed_untrain_ret must contain, and not * end with, the 0xc3 byte of the RET. * 3) STIBP must be enabled, or SMT disabled, to prevent the sibling thread * from re-poisioning the BTB prediction. */ .align 64 - .skip 64 - (zen_return_thunk - zen_untrain_ret), 0xcc -SYM_FUNC_START_NOALIGN(zen_untrain_ret); + .skip 64 - (retbleed_return_thunk - retbleed_untrain_ret), 0xcc +SYM_FUNC_START_NOALIGN(retbleed_untrain_ret); /* - * As executed from zen_untrain_ret, this is: + * As executed from retbleed_untrain_ret, this is: * * TEST $0xcc, %bl * LFENCE - * JMP zen_return_thunk + * JMP retbleed_return_thunk * * Executing the TEST instruction has a side effect of evicting any BTB * prediction (potentially attacker controlled) attached to the RET, as - * zen_return_thunk + 1 isn't an instruction boundary at the moment. + * retbleed_return_thunk + 1 isn't an instruction boundary at the moment. */ .byte 0xf6 /* - * As executed from zen_return_thunk, this is a plain RET. + * As executed from retbleed_return_thunk, this is a plain RET. * * As part of the TEST above, RET is the ModRM byte, and INT3 the imm8. * @@ -166,13 +166,13 @@ SYM_FUNC_START_NOALIGN(zen_untrain_ret); * With SMT enabled and STIBP active, a sibling thread cannot poison * RET's prediction to a type of its choice, but can evict the * prediction due to competitive sharing. If the prediction is - * evicted, zen_return_thunk will suffer Straight Line Speculation + * evicted, retbleed_return_thunk will suffer Straight Line Speculation * which will be contained safely by the INT3. */ -SYM_INNER_LABEL(zen_return_thunk, SYM_L_GLOBAL) +SYM_INNER_LABEL(retbleed_return_thunk, SYM_L_GLOBAL) ret int3 -SYM_CODE_END(zen_return_thunk) +SYM_CODE_END(retbleed_return_thunk) /* * Ensure the TEST decoding / BTB invalidation is complete. @@ -183,13 +183,13 @@ SYM_CODE_END(zen_return_thunk) * Jump back and execute the RET in the middle of the TEST instruction. * INT3 is for SLS protection. */ - jmp zen_return_thunk + jmp retbleed_return_thunk int3 -SYM_FUNC_END(zen_untrain_ret) -__EXPORT_THUNK(zen_untrain_ret) +SYM_FUNC_END(retbleed_untrain_ret) +__EXPORT_THUNK(retbleed_untrain_ret) /* - * SRSO untraining sequence for Zen1/2, similar to zen_untrain_ret() + * SRSO untraining sequence for Zen1/2, similar to retbleed_untrain_ret() * above. On kernel entry, srso_untrain_ret() is executed which is a * * movabs $0xccccccc308c48348,%rax --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -655,5 +655,5 @@ bool arch_is_rethunk(struct symbol *sym) return !strcmp(sym->name, "__x86_return_thunk") || !strcmp(sym->name, "srso_untrain_ret") || !strcmp(sym->name, "srso_safe_ret") || - !strcmp(sym->name, "zen_return_thunk"); + !strcmp(sym->name, "retbleed_return_thunk"); } --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1165,7 +1165,7 @@ static int add_jump_destinations(struct continue; /* - * This is a special case for zen_untrain_ret(). + * This is a special case for retbleed_untrain_ret(). * It jumps to __x86_return_thunk(), but objtool * can't find the thunk's starting RET * instruction, because the RET is also in the
