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x86/cpu: Rename original retbleed methods

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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@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.909378169@infradead.org
This commit is contained in:
Peter Zijlstra 2023-08-14 13:44:32 +02:00 committed by Borislav Petkov (AMD)
parent d43490d0ab
commit d025b7bac0
6 changed files with 23 additions and 23 deletions
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8
arch/x86/include/asm/nospec-branch.h
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@ -272,7 +272,7 @@
.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
@ -282,7 +282,7 @@
* 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
@ -347,11 +347,11 @@ 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);

2
arch/x86/kernel/cpu/bugs.c
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@ -1043,7 +1043,7 @@ 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)

2
arch/x86/kernel/vmlinux.lds.S
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@ -521,7 +521,7 @@ 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

30
arch/x86/lib/retpoline.S
View File

@ -188,32 +188,32 @@ 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_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE)
.skip 64 - (retbleed_return_thunk - retbleed_untrain_ret), 0xcc
SYM_START(retbleed_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE)
ANNOTATE_NOENDBR
/*
* 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.
*
@ -225,13 +225,13 @@ SYM_START(zen_untrain_ret, SYM_L_GLOBAL, SYM_A_NONE)
* 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.
@ -242,13 +242,13 @@ 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 $0xccccc30824648d48,%rax

2
tools/objtool/arch/x86/decode.c
View File

@ -829,6 +829,6 @@ bool arch_is_rethunk(struct symbol *sym)
bool arch_is_embedded_insn(struct symbol *sym)
{
return !strcmp(sym->name, "zen_return_thunk") ||
return !strcmp(sym->name, "retbleed_return_thunk") ||
!strcmp(sym->name, "srso_safe_ret");
}

2
tools/objtool/check.c
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@ -1593,7 +1593,7 @@ static int add_jump_destinations(struct objtool_file *file)
struct symbol *sym = find_symbol_by_offset(dest_sec, dest_off);
/*
* 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