diff --git a/arch/x86/entry/common.c b/arch/x86/entry/common.c
index 6de50b80702e61087c432faf580a0ab063d22507..51cc9c7cb9bdc0e1181d08e33c05b5cc1f177830 100644
--- a/arch/x86/entry/common.c
+++ b/arch/x86/entry/common.c
@@ -255,6 +255,71 @@ __visible noinstr void do_int80_emulation(struct pt_regs *regs)
instrumentation_end();
syscall_exit_to_user_mode(regs);
}
+
+#ifdef CONFIG_X86_FRED
+/*
+ * A FRED-specific INT80 handler is warranted for the follwing reasons:
+ *
+ * 1) As INT instructions and hardware interrupts are separate event
+ * types, FRED does not preclude the use of vector 0x80 for external
+ * interrupts. As a result, the FRED setup code does not reserve
+ * vector 0x80 and calling int80_is_external() is not merely
+ * suboptimal but actively incorrect: it could cause a system call
+ * to be incorrectly ignored.
+ *
+ * 2) It is called only for handling vector 0x80 of event type
+ * EVENT_TYPE_SWINT and will never be called to handle any external
+ * interrupt (event type EVENT_TYPE_EXTINT).
+ *
+ * 3) FRED has separate entry flows depending on if the event came from
+ * user space or kernel space, and because the kernel does not use
+ * INT insns, the FRED kernel entry handler fred_entry_from_kernel()
+ * falls through to fred_bad_type() if the event type is
+ * EVENT_TYPE_SWINT, i.e., INT insns. So if the kernel is handling
+ * an INT insn, it can only be from a user level.
+ *
+ * 4) int80_emulation() does a CLEAR_BRANCH_HISTORY. While FRED will
+ * likely take a different approach if it is ever needed: it
+ * probably belongs in either fred_intx()/ fred_other() or
+ * asm_fred_entrypoint_user(), depending on if this ought to be done
+ * for all entries from userspace or only system
+ * calls.
+ *
+ * 5) INT $0x80 is the fast path for 32-bit system calls under FRED.
+ */
+DEFINE_FREDENTRY_RAW(int80_emulation)
+{
+ int nr;
+
+ enter_from_user_mode(regs);
+
+ instrumentation_begin();
+ add_random_kstack_offset();
+
+ /*
+ * FRED pushed 0 into regs::orig_ax and regs::ax contains the
+ * syscall number.
+ *
+ * User tracing code (ptrace or signal handlers) might assume
+ * that the regs::orig_ax contains a 32-bit number on invoking
+ * a 32-bit syscall.
+ *
+ * Establish the syscall convention by saving the 32bit truncated
+ * syscall number in regs::orig_ax and by invalidating regs::ax.
+ */
+ regs->orig_ax = regs->ax & GENMASK(31, 0);
+ regs->ax = -ENOSYS;
+
+ nr = syscall_32_enter(regs);
+
+ local_irq_enable();
+ nr = syscall_enter_from_user_mode_work(regs, nr);
+ do_syscall_32_irqs_on(regs, nr);
+
+ instrumentation_end();
+ syscall_exit_to_user_mode(regs);
+}
+#endif
#else /* CONFIG_IA32_EMULATION */
/* Handles int $0x80 on a 32bit kernel */
diff --git a/arch/x86/entry/entry_fred.c b/arch/x86/entry/entry_fred.c
index ac120cbdaaf2b4c474954c9a9f148222a370a72a..89c1476fcdd9f95825c0dbbb320b86b66360ce9e 100644
--- a/arch/x86/entry/entry_fred.c
+++ b/arch/x86/entry/entry_fred.c
@@ -28,9 +28,9 @@ static noinstr void fred_bad_type(struct pt_regs *regs, unsigned long error_code
if (regs->fred_cs.sl > 0) {
pr_emerg("PANIC: invalid or fatal FRED event; event type %u "
"vector %u error 0x%lx aux 0x%lx at %04x:%016lx\n",
- regs->fred_ss.type, regs->fred_ss.vector, regs->orig_ax,
+ regs->fred_ss.type, regs->fred_ss.vector, error_code,
fred_event_data(regs), regs->cs, regs->ip);
- die("invalid or fatal FRED event", regs, regs->orig_ax);
+ die("invalid or fatal FRED event", regs, error_code);
panic("invalid or fatal FRED event");
} else {
unsigned long flags = oops_begin();
@@ -38,10 +38,10 @@ static noinstr void fred_bad_type(struct pt_regs *regs, unsigned long error_code
pr_alert("BUG: invalid or fatal FRED event; event type %u "
"vector %u error 0x%lx aux 0x%lx at %04x:%016lx\n",
- regs->fred_ss.type, regs->fred_ss.vector, regs->orig_ax,
+ regs->fred_ss.type, regs->fred_ss.vector, error_code,
fred_event_data(regs), regs->cs, regs->ip);
- if (__die("Invalid or fatal FRED event", regs, regs->orig_ax))
+ if (__die("Invalid or fatal FRED event", regs, error_code))
sig = 0;
oops_end(flags, regs, sig);
@@ -66,7 +66,7 @@ static noinstr void fred_intx(struct pt_regs *regs)
/* INT80 */
case IA32_SYSCALL_VECTOR:
if (ia32_enabled())
- return int80_emulation(regs);
+ return fred_int80_emulation(regs);
fallthrough;
#endif
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index ca295b0c1eeee05b812c27bb88bd814dba3c1f00..ab18185894dfd5e9c3f09f5fa39ac4c8ef72e7f4 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1652,7 +1652,8 @@ static void __init bhi_select_mitigation(void)
return;
/* Retpoline mitigates against BHI unless the CPU has RRSBA behavior */
- if (cpu_feature_enabled(X86_FEATURE_RETPOLINE)) {
+ if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+ !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE)) {
spec_ctrl_disable_kernel_rrsba();
if (rrsba_disabled)
return;
@@ -2804,11 +2805,13 @@ static const char *spectre_bhi_state(void)
{
if (!boot_cpu_has_bug(X86_BUG_BHI))
return "; BHI: Not affected";
- else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW))
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_HW))
return "; BHI: BHI_DIS_S";
- else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP))
+ else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP))
return "; BHI: SW loop, KVM: SW loop";
- else if (boot_cpu_has(X86_FEATURE_RETPOLINE) && rrsba_disabled)
+ else if (boot_cpu_has(X86_FEATURE_RETPOLINE) &&
+ !boot_cpu_has(X86_FEATURE_RETPOLINE_LFENCE) &&
+ rrsba_disabled)
return "; BHI: Retpoline";
else if (boot_cpu_has(X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT))
return "; BHI: Vulnerable, KVM: SW loop";
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index b7174209d855c634a701aaf489372b087f464006..946813d816bfc2948eccc823300db283f99f91d4 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -44,7 +44,10 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_F16C, X86_FEATURE_XMM2, },
{ X86_FEATURE_AES, X86_FEATURE_XMM2 },
{ X86_FEATURE_SHA_NI, X86_FEATURE_XMM2 },
+ { X86_FEATURE_GFNI, X86_FEATURE_XMM2 },
{ X86_FEATURE_FMA, X86_FEATURE_AVX },
+ { X86_FEATURE_VAES, X86_FEATURE_AVX },
+ { X86_FEATURE_VPCLMULQDQ, X86_FEATURE_AVX },
{ X86_FEATURE_AVX2, X86_FEATURE_AVX, },
{ X86_FEATURE_AVX512F, X86_FEATURE_AVX, },
{ X86_FEATURE_AVX512IFMA, X86_FEATURE_AVX512F },
@@ -56,9 +59,6 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_AVX512VL, X86_FEATURE_AVX512F },
{ X86_FEATURE_AVX512VBMI, X86_FEATURE_AVX512F },
{ X86_FEATURE_AVX512_VBMI2, X86_FEATURE_AVX512VL },
- { X86_FEATURE_GFNI, X86_FEATURE_AVX512VL },
- { X86_FEATURE_VAES, X86_FEATURE_AVX512VL },
- { X86_FEATURE_VPCLMULQDQ, X86_FEATURE_AVX512VL },
{ X86_FEATURE_AVX512_VNNI, X86_FEATURE_AVX512VL },
{ X86_FEATURE_AVX512_BITALG, X86_FEATURE_AVX512VL },
{ X86_FEATURE_AVX512_4VNNIW, X86_FEATURE_AVX512F },
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S
index e674ccf720b9f6befe6ffb0fccec192fb1aa9a89..391059b2c6fbc4a571f0582c7c4654147a930cef 100644
--- a/arch/x86/lib/retpoline.S
+++ b/arch/x86/lib/retpoline.S
@@ -382,8 +382,15 @@ SYM_FUNC_END(call_depth_return_thunk)
SYM_CODE_START(__x86_return_thunk)
UNWIND_HINT_FUNC
ANNOTATE_NOENDBR
+#if defined(CONFIG_MITIGATION_UNRET_ENTRY) || \
+ defined(CONFIG_MITIGATION_SRSO) || \
+ defined(CONFIG_MITIGATION_CALL_DEPTH_TRACKING)
ALTERNATIVE __stringify(ANNOTATE_UNRET_SAFE; ret), \
"jmp warn_thunk_thunk", X86_FEATURE_ALWAYS
+#else
+ ANNOTATE_UNRET_SAFE
+ ret
+#endif
int3
SYM_CODE_END(__x86_return_thunk)
EXPORT_SYMBOL(__x86_return_thunk)