Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Ingo Molnar:
 "Another round of CR3/PCID related fixes (I think this addresses all
  but one of the known problems with PCID support), an objtool fix plus
  a Clang fix that (finally) solves all Clang quirks to build a bootable
  x86 kernel as-is"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/asm: Fix inline asm call constraints for Clang
  objtool: Handle another GCC stack pointer adjustment bug
  x86/mm/32: Load a sane CR3 before cpu_init() on secondary CPUs
  x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE_PCID) earlier
  x86/mm/64: Stop using CR3.PCID == 0 in ASID-aware code
  x86/mm: Factor out CR3-building code

arch/x86/include/asm/alternative.h

@@ -218,10 +218,9 @@ static inline int alternatives_text_reserved(void *start, void *end)
 #define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2,   \
 			   output, input...)				      \
 {									      \
-	register void *__sp asm(_ASM_SP);				      \
 	asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
 		"call %P[new2]", feature2)				      \
-		: output, "+r" (__sp)					      \
+		: output, ASM_CALL_CONSTRAINT				      \
 		: [old] "i" (oldfunc), [new1] "i" (newfunc1),		      \
 		  [new2] "i" (newfunc2), ## input);			      \
 }

arch/x86/include/asm/asm.h

@@ -132,4 +132,15 @@
 /* For C file, we already have NOKPROBE_SYMBOL macro */
 #endif
 
+#ifndef __ASSEMBLY__
+/*
+ * This output constraint should be used for any inline asm which has a "call"
+ * instruction.  Otherwise the asm may be inserted before the frame pointer
+ * gets set up by the containing function.  If you forget to do this, objtool
+ * may print a "call without frame pointer save/setup" warning.
+ */
+register unsigned int __asm_call_sp asm("esp");
+#define ASM_CALL_CONSTRAINT "+r" (__asm_call_sp)
+#endif
+
 #endif /* _ASM_X86_ASM_H */

arch/x86/include/asm/mmu_context.h

@@ -286,6 +286,32 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
 	return __pkru_allows_pkey(vma_pkey(vma), write);
 }
 
+/*
+ * If PCID is on, ASID-aware code paths put the ASID+1 into the PCID
+ * bits.  This serves two purposes.  It prevents a nasty situation in
+ * which PCID-unaware code saves CR3, loads some other value (with PCID
+ * == 0), and then restores CR3, thus corrupting the TLB for ASID 0 if
+ * the saved ASID was nonzero.  It also means that any bugs involving
+ * loading a PCID-enabled CR3 with CR4.PCIDE off will trigger
+ * deterministically.
+ */
+
+static inline unsigned long build_cr3(struct mm_struct *mm, u16 asid)
+{
+	if (static_cpu_has(X86_FEATURE_PCID)) {
+		VM_WARN_ON_ONCE(asid > 4094);
+		return __sme_pa(mm->pgd) | (asid + 1);
+	} else {
+		VM_WARN_ON_ONCE(asid != 0);
+		return __sme_pa(mm->pgd);
+	}
+}
+
+static inline unsigned long build_cr3_noflush(struct mm_struct *mm, u16 asid)
+{
+	VM_WARN_ON_ONCE(asid > 4094);
+	return __sme_pa(mm->pgd) | (asid + 1) | CR3_NOFLUSH;
+}
 
 /*
  * This can be used from process context to figure out what the value of
@@ -296,10 +322,8 @@ static inline bool arch_vma_access_permitted(struct vm_area_struct *vma,
  */
 static inline unsigned long __get_current_cr3_fast(void)
 {
-	unsigned long cr3 = __pa(this_cpu_read(cpu_tlbstate.loaded_mm)->pgd);
-
-	if (static_cpu_has(X86_FEATURE_PCID))
-		cr3 |= this_cpu_read(cpu_tlbstate.loaded_mm_asid);
+	unsigned long cr3 = build_cr3(this_cpu_read(cpu_tlbstate.loaded_mm),
+		this_cpu_read(cpu_tlbstate.loaded_mm_asid));
 
 	/* For now, be very restrictive about when this can be called. */
 	VM_WARN_ON(in_nmi() || preemptible());

arch/x86/include/asm/mshyperv.h

@@ -179,7 +179,6 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 	u64 input_address = input ? virt_to_phys(input) : 0;
 	u64 output_address = output ? virt_to_phys(output) : 0;
 	u64 hv_status;
-	register void *__sp asm(_ASM_SP);
 
 #ifdef CONFIG_X86_64
 	if (!hv_hypercall_pg)
@@ -187,7 +186,7 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 
 	__asm__ __volatile__("mov %4, %%r8\n"
 			     "call *%5"
-			     : "=a" (hv_status), "+r" (__sp),
+			     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
 			       "+c" (control), "+d" (input_address)
 			     :  "r" (output_address), "m" (hv_hypercall_pg)
 			     : "cc", "memory", "r8", "r9", "r10", "r11");
@@ -202,7 +201,7 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 
 	__asm__ __volatile__("call *%7"
 			     : "=A" (hv_status),
-			       "+c" (input_address_lo), "+r" (__sp)
+			       "+c" (input_address_lo), ASM_CALL_CONSTRAINT
 			     : "A" (control),
 			       "b" (input_address_hi),
 			       "D"(output_address_hi), "S"(output_address_lo),
@@ -224,12 +223,11 @@ static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
 static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
 {
 	u64 hv_status, control = (u64)code | HV_HYPERCALL_FAST_BIT;
-	register void *__sp asm(_ASM_SP);
 
 #ifdef CONFIG_X86_64
 	{
 		__asm__ __volatile__("call *%4"
-				     : "=a" (hv_status), "+r" (__sp),
+				     : "=a" (hv_status), ASM_CALL_CONSTRAINT,
 				       "+c" (control), "+d" (input1)
 				     : "m" (hv_hypercall_pg)
 				     : "cc", "r8", "r9", "r10", "r11");
@@ -242,7 +240,7 @@ static inline u64 hv_do_fast_hypercall8(u16 code, u64 input1)
 		__asm__ __volatile__ ("call *%5"
 				      : "=A"(hv_status),
 					"+c"(input1_lo),
-					"+r"(__sp)
+					ASM_CALL_CONSTRAINT
 				      :	"A" (control),
 					"b" (input1_hi),
 					"m" (hv_hypercall_pg)

arch/x86/include/asm/paravirt_types.h

@@ -459,8 +459,8 @@ int paravirt_disable_iospace(void);
  */
 #ifdef CONFIG_X86_32
 #define PVOP_VCALL_ARGS							\
-	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx;	\
-	register void *__sp asm("esp")
+	unsigned long __eax = __eax, __edx = __edx, __ecx = __ecx;
+
 #define PVOP_CALL_ARGS			PVOP_VCALL_ARGS
 
 #define PVOP_CALL_ARG1(x)		"a" ((unsigned long)(x))
@@ -480,8 +480,8 @@ int paravirt_disable_iospace(void);
 /* [re]ax isn't an arg, but the return val */
 #define PVOP_VCALL_ARGS						\
 	unsigned long __edi = __edi, __esi = __esi,		\
-		__edx = __edx, __ecx = __ecx, __eax = __eax;	\
-	register void *__sp asm("rsp")
+		__edx = __edx, __ecx = __ecx, __eax = __eax;
+
 #define PVOP_CALL_ARGS		PVOP_VCALL_ARGS
 
 #define PVOP_CALL_ARG1(x)		"D" ((unsigned long)(x))
@@ -532,7 +532,7 @@ int paravirt_disable_iospace(void);
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : call_clbr, "+r" (__sp)		\
+				     : call_clbr, ASM_CALL_CONSTRAINT	\
 				     : paravirt_type(op),		\
 				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
@@ -542,7 +542,7 @@ int paravirt_disable_iospace(void);
 			asm volatile(pre				\
 				     paravirt_alt(PARAVIRT_CALL)	\
 				     post				\
-				     : call_clbr, "+r" (__sp)		\
+				     : call_clbr, ASM_CALL_CONSTRAINT	\
 				     : paravirt_type(op),		\
 				       paravirt_clobber(clbr),		\
 				       ##__VA_ARGS__			\
@@ -569,7 +569,7 @@ int paravirt_disable_iospace(void);
 		asm volatile(pre					\
 			     paravirt_alt(PARAVIRT_CALL)		\
 			     post					\
-			     : call_clbr, "+r" (__sp)			\
+			     : call_clbr, ASM_CALL_CONSTRAINT		\
 			     : paravirt_type(op),			\
 			       paravirt_clobber(clbr),			\
 			       ##__VA_ARGS__				\

arch/x86/include/asm/preempt.h

@@ -101,18 +101,13 @@ static __always_inline bool should_resched(int preempt_offset)
 #ifdef CONFIG_PREEMPT
   extern asmlinkage void ___preempt_schedule(void);
 # define __preempt_schedule() \
-({								\
-	register void *__sp asm(_ASM_SP);			\
-	asm volatile ("call ___preempt_schedule" : "+r"(__sp));	\
-})
+	asm volatile ("call ___preempt_schedule" : ASM_CALL_CONSTRAINT)
 
   extern asmlinkage void preempt_schedule(void);
   extern asmlinkage void ___preempt_schedule_notrace(void);
 # define __preempt_schedule_notrace() \
-({									\
-	register void *__sp asm(_ASM_SP);				\
-	asm volatile ("call ___preempt_schedule_notrace" : "+r"(__sp));	\
-})
+	asm volatile ("call ___preempt_schedule_notrace" : ASM_CALL_CONSTRAINT)
+
   extern asmlinkage void preempt_schedule_notrace(void);
 #endif
 

arch/x86/include/asm/processor.h

@@ -677,8 +677,6 @@ static inline void sync_core(void)
 	 * Like all of Linux's memory ordering operations, this is a
 	 * compiler barrier as well.
 	 */
-	register void *__sp asm(_ASM_SP);
-
 #ifdef CONFIG_X86_32
 	asm volatile (
 		"pushfl\n\t"
@@ -686,7 +684,7 @@ static inline void sync_core(void)
 		"pushl $1f\n\t"
 		"iret\n\t"
 		"1:"
-		: "+r" (__sp) : : "memory");
+		: ASM_CALL_CONSTRAINT : : "memory");
 #else
 	unsigned int tmp;
 
@@ -703,7 +701,7 @@ static inline void sync_core(void)
 		"iretq\n\t"
 		UNWIND_HINT_RESTORE
 		"1:"
-		: "=&r" (tmp), "+r" (__sp) : : "cc", "memory");
+		: "=&r" (tmp), ASM_CALL_CONSTRAINT : : "cc", "memory");
 #endif
 }
 

arch/x86/include/asm/rwsem.h

@@ -103,7 +103,6 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
 ({							\
 	long tmp;					\
 	struct rw_semaphore* ret;			\
-	register void *__sp asm(_ASM_SP);		\
 							\
 	asm volatile("# beginning down_write\n\t"	\
 		     LOCK_PREFIX "  xadd      %1,(%4)\n\t"	\
@@ -114,7 +113,8 @@ static inline bool __down_read_trylock(struct rw_semaphore *sem)
 		     "  call " slow_path "\n"		\
 		     "1:\n"				\
 		     "# ending down_write"		\
-		     : "+m" (sem->count), "=d" (tmp), "=a" (ret), "+r" (__sp) \
+		     : "+m" (sem->count), "=d" (tmp),	\
+		       "=a" (ret), ASM_CALL_CONSTRAINT	\
 		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
 		     : "memory", "cc");			\
 	ret;						\

arch/x86/include/asm/uaccess.h

@@ -166,11 +166,11 @@ __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
 ({									\
 	int __ret_gu;							\
 	register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX);		\
-	register void *__sp asm(_ASM_SP);				\
 	__chk_user_ptr(ptr);						\
 	might_fault();							\
 	asm volatile("call __get_user_%P4"				\
-		     : "=a" (__ret_gu), "=r" (__val_gu), "+r" (__sp)	\
+		     : "=a" (__ret_gu), "=r" (__val_gu),		\
+			ASM_CALL_CONSTRAINT				\
 		     : "0" (ptr), "i" (sizeof(*(ptr))));		\
 	(x) = (__force __typeof__(*(ptr))) __val_gu;			\
 	__builtin_expect(__ret_gu, 0);					\

arch/x86/include/asm/xen/hypercall.h

@@ -113,10 +113,9 @@ extern struct { char _entry[32]; } hypercall_page[];
 	register unsigned long __arg2 asm(__HYPERCALL_ARG2REG) = __arg2; \
 	register unsigned long __arg3 asm(__HYPERCALL_ARG3REG) = __arg3; \
 	register unsigned long __arg4 asm(__HYPERCALL_ARG4REG) = __arg4; \
-	register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5; \
-	register void *__sp asm(_ASM_SP);
+	register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5;
 
-#define __HYPERCALL_0PARAM	"=r" (__res), "+r" (__sp)
+#define __HYPERCALL_0PARAM	"=r" (__res), ASM_CALL_CONSTRAINT
 #define __HYPERCALL_1PARAM	__HYPERCALL_0PARAM, "+r" (__arg1)
 #define __HYPERCALL_2PARAM	__HYPERCALL_1PARAM, "+r" (__arg2)
 #define __HYPERCALL_3PARAM	__HYPERCALL_2PARAM, "+r" (__arg3)

arch/x86/kernel/cpu/bugs.c

@@ -21,14 +21,6 @@
 
 void __init check_bugs(void)
 {
-#ifdef CONFIG_X86_32
-	/*
-	 * Regardless of whether PCID is enumerated, the SDM says
-	 * that it can't be enabled in 32-bit mode.
-	 */
-	setup_clear_cpu_cap(X86_FEATURE_PCID);
-#endif
-
 	identify_boot_cpu();
 
 	if (!IS_ENABLED(CONFIG_SMP)) {

arch/x86/kernel/cpu/common.c

@@ -904,6 +904,14 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
 	fpu__init_system(c);
+
+#ifdef CONFIG_X86_32
+	/*
+	 * Regardless of whether PCID is enumerated, the SDM says
+	 * that it can't be enabled in 32-bit mode.
+	 */
+	setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
 }
 
 void __init early_cpu_init(void)

arch/x86/kernel/smpboot.c

@@ -232,12 +232,6 @@ static void notrace start_secondary(void *unused)
 	 */
 	if (boot_cpu_has(X86_FEATURE_PCID))
 		__write_cr4(__read_cr4() | X86_CR4_PCIDE);
-	cpu_init();
-	x86_cpuinit.early_percpu_clock_init();
-	preempt_disable();
-	smp_callin();
-
-	enable_start_cpu0 = 0;
 
 #ifdef CONFIG_X86_32
 	/* switch away from the initial page table */
@@ -245,6 +239,13 @@ static void notrace start_secondary(void *unused)
 	__flush_tlb_all();
 #endif
 
+	cpu_init();
+	x86_cpuinit.early_percpu_clock_init();
+	preempt_disable();
+	smp_callin();
+
+	enable_start_cpu0 = 0;
+
 	/* otherwise gcc will move up smp_processor_id before the cpu_init */
 	barrier();
 	/*

arch/x86/kvm/emulate.c

@@ -5298,7 +5298,6 @@ static void fetch_possible_mmx_operand(struct x86_emulate_ctxt *ctxt,
 
 static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *))
 {
-	register void *__sp asm(_ASM_SP);
 	ulong flags = (ctxt->eflags & EFLAGS_MASK) | X86_EFLAGS_IF;
 
 	if (!(ctxt->d & ByteOp))
@@ -5306,7 +5305,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, void (*fop)(struct fastop *))
 
 	asm("push %[flags]; popf; call *%[fastop]; pushf; pop %[flags]\n"
 	    : "+a"(ctxt->dst.val), "+d"(ctxt->src.val), [flags]"+D"(flags),
-	      [fastop]"+S"(fop), "+r"(__sp)
+	      [fastop]"+S"(fop), ASM_CALL_CONSTRAINT
 	    : "c"(ctxt->src2.val));
 
 	ctxt->eflags = (ctxt->eflags & ~EFLAGS_MASK) | (flags & EFLAGS_MASK);

arch/x86/kvm/vmx.c

@@ -9045,7 +9045,6 @@ static void vmx_complete_atomic_exit(struct vcpu_vmx *vmx)
 static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
 {
 	u32 exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
-	register void *__sp asm(_ASM_SP);
 
 	if ((exit_intr_info & (INTR_INFO_VALID_MASK | INTR_INFO_INTR_TYPE_MASK))
 			== (INTR_INFO_VALID_MASK | INTR_TYPE_EXT_INTR)) {
@@ -9074,7 +9073,7 @@ static void vmx_handle_external_intr(struct kvm_vcpu *vcpu)
 #ifdef CONFIG_X86_64
 			[sp]"=&r"(tmp),
 #endif
-			"+r"(__sp)
+			ASM_CALL_CONSTRAINT
 			:
 			[entry]"r"(entry),
 			[ss]"i"(__KERNEL_DS),

arch/x86/mm/fault.c

@@ -806,7 +806,6 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 	if (is_vmalloc_addr((void *)address) &&
 	    (((unsigned long)tsk->stack - 1 - address < PAGE_SIZE) ||
 	     address - ((unsigned long)tsk->stack + THREAD_SIZE) < PAGE_SIZE)) {
-		register void *__sp asm("rsp");
 		unsigned long stack = this_cpu_read(orig_ist.ist[DOUBLEFAULT_STACK]) - sizeof(void *);
 		/*
 		 * We're likely to be running with very little stack space
@@ -821,7 +820,7 @@ no_context(struct pt_regs *regs, unsigned long error_code,
 		asm volatile ("movq %[stack], %%rsp\n\t"
 			      "call handle_stack_overflow\n\t"
 			      "1: jmp 1b"
-			      : "+r" (__sp)
+			      : ASM_CALL_CONSTRAINT
 			      : "D" ("kernel stack overflow (page fault)"),
 				"S" (regs), "d" (address),
 				[stack] "rm" (stack));

arch/x86/mm/tlb.c

@@ -126,8 +126,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 	 * isn't free.
 	 */
 #ifdef CONFIG_DEBUG_VM
-	if (WARN_ON_ONCE(__read_cr3() !=
-			 (__sme_pa(real_prev->pgd) | prev_asid))) {
+	if (WARN_ON_ONCE(__read_cr3() != build_cr3(real_prev, prev_asid))) {
 		/*
 		 * If we were to BUG here, we'd be very likely to kill
 		 * the system so hard that we don't see the call trace.
@@ -172,7 +171,7 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 			 */
 			this_cpu_write(cpu_tlbstate.ctxs[prev_asid].tlb_gen,
 				       next_tlb_gen);
-			write_cr3(__sme_pa(next->pgd) | prev_asid);
+			write_cr3(build_cr3(next, prev_asid));
 			trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH,
 					TLB_FLUSH_ALL);
 		}
@@ -216,12 +215,12 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 		if (need_flush) {
 			this_cpu_write(cpu_tlbstate.ctxs[new_asid].ctx_id, next->context.ctx_id);
 			this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
-			write_cr3(__sme_pa(next->pgd) | new_asid);
+			write_cr3(build_cr3(next, new_asid));
 			trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH,
 					TLB_FLUSH_ALL);
 		} else {
 			/* The new ASID is already up to date. */
-			write_cr3(__sme_pa(next->pgd) | new_asid | CR3_NOFLUSH);
+			write_cr3(build_cr3_noflush(next, new_asid));
 			trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, 0);
 		}
 
@@ -265,7 +264,7 @@ void initialize_tlbstate_and_flush(void)
 		!(cr4_read_shadow() & X86_CR4_PCIDE));
 
 	/* Force ASID 0 and force a TLB flush. */
-	write_cr3(cr3 & ~CR3_PCID_MASK);
+	write_cr3(build_cr3(mm, 0));
 
 	/* Reinitialize tlbstate. */
 	this_cpu_write(cpu_tlbstate.loaded_mm_asid, 0);

tools/objtool/Documentation/stack-validation.txt

@@ -194,10 +194,10 @@ they mean, and suggestions for how to fix them.
    If it's a GCC-compiled .c file, the error may be because the function
    uses an inline asm() statement which has a "call" instruction.  An
    asm() statement with a call instruction must declare the use of the
-   stack pointer in its output operand.  For example, on x86_64:
+   stack pointer in its output operand.  On x86_64, this means adding
+   the ASM_CALL_CONSTRAINT as an output constraint:
 
-     register void *__sp asm("rsp");
-     asm volatile("call func" : "+r" (__sp));
+     asm volatile("call func" : ASM_CALL_CONSTRAINT);
 
    Otherwise the stack frame may not get created before the call.
 

tools/objtool/arch/x86/decode.c

@@ -208,14 +208,14 @@ int arch_decode_instruction(struct elf *elf, struct section *sec,
 		break;
 
 	case 0x89:
-		if (rex == 0x48 && modrm == 0xe5) {
+		if (rex_w && !rex_r && modrm_mod == 3 && modrm_reg == 4) {
 
-			/* mov %rsp, %rbp */
+			/* mov %rsp, reg */
 			*type = INSN_STACK;
 			op->src.type = OP_SRC_REG;
 			op->src.reg = CFI_SP;
 			op->dest.type = OP_DEST_REG;
-			op->dest.reg = CFI_BP;
+			op->dest.reg = op_to_cfi_reg[modrm_rm][rex_b];
 			break;
 		}
 

tools/objtool/check.c

@@ -1203,9 +1203,8 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
 		switch (op->src.type) {
 
 		case OP_SRC_REG:
-			if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP) {
-
-				if (cfa->base == CFI_SP &&
+			if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP &&
+			    cfa->base == CFI_SP &&
 			    regs[CFI_BP].base == CFI_CFA &&
 			    regs[CFI_BP].offset == -cfa->offset) {
 
@@ -1214,13 +1213,29 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state)
 				state->bp_scratch = false;
 			}
 
-				else if (state->drap) {
+			else if (op->src.reg == CFI_SP &&
+				 op->dest.reg == CFI_BP && state->drap) {
 
 				/* drap: mov %rsp, %rbp */
 				regs[CFI_BP].base = CFI_BP;
 				regs[CFI_BP].offset = -state->stack_size;
 				state->bp_scratch = false;
 			}
+
+			else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) {
+
+				/*
+				 * mov %rsp, %reg
+				 *
+				 * This is needed for the rare case where GCC
+				 * does:
+				 *
+				 *   mov    %rsp, %rax
+				 *   ...
+				 *   mov    %rax, %rsp
+				 */
+				state->vals[op->dest.reg].base = CFI_CFA;
+				state->vals[op->dest.reg].offset = -state->stack_size;
 			}
 
 			else if (op->dest.reg == cfa->base) {