Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

 - Fix kernel build with the integrated LLVM assembler which doesn't see
   the -Wa,-march option.

 - Fix "make vdso_install" when COMPAT_VDSO is disabled.

 - Make KVM more robust if the AT S1E1R instruction triggers an
   exception (architecture corner cases).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  KVM: arm64: Set HCR_EL2.PTW to prevent AT taking synchronous exception
  KVM: arm64: Survive synchronous exceptions caused by AT instructions
  KVM: arm64: Add kvm_extable for vaxorcism code
  arm64: vdso32: make vdso32 install conditional
  arm64: use a common .arch preamble for inline assembly

5 files changed, 95 insertions, 34 deletions

diff --git a/arch/arm64/kvm/hyp/entry.S b/arch/arm64/kvm/hyp/entry.S
index ee32a7743389..76e7eaf4675e 100644
--- a/arch/arm64/kvm/hyp/entry.S
+++ b/arch/arm64/kvm/hyp/entry.S
@@ -196,20 +196,23 @@ alternative_endif
 	// This is our single instruction exception window. A pending
 	// SError is guaranteed to occur at the earliest when we unmask
 	// it, and at the latest just after the ISB.
-	.global	abort_guest_exit_start
 abort_guest_exit_start:
 
 	isb
 
-	.global	abort_guest_exit_end
 abort_guest_exit_end:
 
 	msr	daifset, #4	// Mask aborts
+	ret
+
+	_kvm_extable	abort_guest_exit_start, 9997f
+	_kvm_extable	abort_guest_exit_end, 9997f
+9997:
+	msr	daifset, #4	// Mask aborts
+	mov	x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
 
-	// If the exception took place, restore the EL1 exception
-	// context so that we can report some information.
-	// Merge the exception code with the SError pending bit.
-	tbz	x0, #ARM_EXIT_WITH_SERROR_BIT, 1f
+	// restore the EL1 exception context so that we can report some
+	// information. Merge the exception code with the SError pending bit.
 	msr	elr_el2, x2
 	msr	esr_el2, x3
 	msr	spsr_el2, x4
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index 689fccbc9de7..46b4dab933d0 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -15,6 +15,30 @@
 #include <asm/kvm_mmu.h>
 #include <asm/mmu.h>
 
+.macro save_caller_saved_regs_vect
+	/* x0 and x1 were saved in the vector entry */
+	stp	x2, x3,   [sp, #-16]!
+	stp	x4, x5,   [sp, #-16]!
+	stp	x6, x7,   [sp, #-16]!
+	stp	x8, x9,   [sp, #-16]!
+	stp	x10, x11, [sp, #-16]!
+	stp	x12, x13, [sp, #-16]!
+	stp	x14, x15, [sp, #-16]!
+	stp	x16, x17, [sp, #-16]!
+.endm
+
+.macro restore_caller_saved_regs_vect
+	ldp	x16, x17, [sp], #16
+	ldp	x14, x15, [sp], #16
+	ldp	x12, x13, [sp], #16
+	ldp	x10, x11, [sp], #16
+	ldp	x8, x9,   [sp], #16
+	ldp	x6, x7,   [sp], #16
+	ldp	x4, x5,   [sp], #16
+	ldp	x2, x3,   [sp], #16
+	ldp	x0, x1,   [sp], #16
+.endm
+
 	.text
 
 .macro do_el2_call
@@ -143,13 +167,19 @@ el1_error:
 	b	__guest_exit
 
 el2_sync:
-	/* Check for illegal exception return, otherwise panic */
+	/* Check for illegal exception return */
 	mrs	x0, spsr_el2
+	tbnz	x0, #20, 1f
 
-	/* if this was something else, then panic! */
-	tst	x0, #PSR_IL_BIT
-	b.eq	__hyp_panic
+	save_caller_saved_regs_vect
+	stp     x29, x30, [sp, #-16]!
+	bl	kvm_unexpected_el2_exception
+	ldp     x29, x30, [sp], #16
+	restore_caller_saved_regs_vect
 
+	eret
+
+1:
 	/* Let's attempt a recovery from the illegal exception return */
 	get_vcpu_ptr	x1, x0
 	mov	x0, #ARM_EXCEPTION_IL
@@ -157,27 +187,14 @@ el2_sync:
 
 
 el2_error:
-	ldp	x0, x1, [sp], #16
+	save_caller_saved_regs_vect
+	stp     x29, x30, [sp, #-16]!
+
+	bl	kvm_unexpected_el2_exception
+
+	ldp     x29, x30, [sp], #16
+	restore_caller_saved_regs_vect
 
-	/*
-	 * Only two possibilities:
-	 * 1) Either we come from the exit path, having just unmasked
-	 *    PSTATE.A: change the return code to an EL2 fault, and
-	 *    carry on, as we're already in a sane state to handle it.
-	 * 2) Or we come from anywhere else, and that's a bug: we panic.
-	 *
-	 * For (1), x0 contains the original return code and x1 doesn't
-	 * contain anything meaningful at that stage. We can reuse them
-	 * as temp registers.
-	 * For (2), who cares?
-	 */
-	mrs	x0, elr_el2
-	adr	x1, abort_guest_exit_start
-	cmp	x0, x1
-	adr	x1, abort_guest_exit_end
-	ccmp	x0, x1, #4, ne
-	b.ne	__hyp_panic
-	mov	x0, #(1 << ARM_EXIT_WITH_SERROR_BIT)
 	eret
 	sb
 
diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
index 426ef65601dd..5b6b8fa00f0a 100644
--- a/arch/arm64/kvm/hyp/include/hyp/switch.h
+++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
@@ -17,6 +17,7 @@
 
 #include <asm/barrier.h>
 #include <asm/cpufeature.h>
+#include <asm/extable.h>
 #include <asm/kprobes.h>
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
@@ -29,6 +30,9 @@
 
 extern const char __hyp_panic_string[];
 
+extern struct exception_table_entry __start___kvm_ex_table;
+extern struct exception_table_entry __stop___kvm_ex_table;
+
 /* Check whether the FP regs were dirtied while in the host-side run loop: */
 static inline bool update_fp_enabled(struct kvm_vcpu *vcpu)
 {
@@ -142,10 +146,10 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
 	 * saved the guest context yet, and we may return early...
 	 */
 	par = read_sysreg(par_el1);
-	asm volatile("at s1e1r, %0" : : "r" (far));
-	isb();
-
-	tmp = read_sysreg(par_el1);
+	if (!__kvm_at("s1e1r", far))
+		tmp = read_sysreg(par_el1);
+	else
+		tmp = SYS_PAR_EL1_F; /* back to the guest */
 	write_sysreg(par, par_el1);
 
 	if (unlikely(tmp & SYS_PAR_EL1_F))
@@ -508,4 +512,31 @@ static inline void __set_host_arch_workaround_state(struct kvm_vcpu *vcpu)
 #endif
 }
 
+static inline void __kvm_unexpected_el2_exception(void)
+{
+	unsigned long addr, fixup;
+	struct kvm_cpu_context *host_ctxt;
+	struct exception_table_entry *entry, *end;
+	unsigned long elr_el2 = read_sysreg(elr_el2);
+
+	entry = hyp_symbol_addr(__start___kvm_ex_table);
+	end = hyp_symbol_addr(__stop___kvm_ex_table);
+	host_ctxt = &__hyp_this_cpu_ptr(kvm_host_data)->host_ctxt;
+
+	while (entry < end) {
+		addr = (unsigned long)&entry->insn + entry->insn;
+		fixup = (unsigned long)&entry->fixup + entry->fixup;
+
+		if (addr != elr_el2) {
+			entry++;
+			continue;
+		}
+
+		write_sysreg(fixup, elr_el2);
+		return;
+	}
+
+	hyp_panic(host_ctxt);
+}
+
 #endif /* __ARM64_KVM_HYP_SWITCH_H__ */
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index 341be2f2f312..0970442d2dbc 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -270,3 +270,8 @@ void __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)
 		       read_sysreg(hpfar_el2), par, vcpu);
 	unreachable();
 }
+
+asmlinkage void kvm_unexpected_el2_exception(void)
+{
+	return __kvm_unexpected_el2_exception();
+}
diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index c52d714e0d75..c1da4f86ccac 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -217,3 +217,8 @@ void __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)
 	__hyp_call_panic(spsr, elr, par, host_ctxt);
 	unreachable();
 }
+
+asmlinkage void kvm_unexpected_el2_exception(void)
+{
+	return __kvm_unexpected_el2_exception();
+}