Revert "KVM: arm64: Add kvm_extable for vaxorcism code"

This reverts commit 8cc25436.
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/include/asm/kvm_asm.h

@@ -146,21 +146,6 @@ extern u32 __kvm_get_mdcr_el2(void);
 	kern_hyp_va	\vcpu
 .endm
 
-/*
- * KVM extable for unexpected exceptions.
- * In the same format _asm_extable, but output to a different section so that
- * it can be mapped to EL2. The KVM version is not sorted. The caller must
- * ensure:
- * x18 has the hypervisor value to allow any Shadow-Call-Stack instrumented
- * code to write to it, and that SPSR_EL2 and ELR_EL2 are restored by the fixup.
- */
-.macro	_kvm_extable, from, to
-	.pushsection	__kvm_ex_table, "a"
-	.align		3
-	.long		(\from - .), (\to - .)
-	.popsection
-.endm
-
 #endif
 
 #endif /* __ARM_KVM_ASM_H__ */

arch/arm64/kernel/vmlinux.lds.S

@@ -24,13 +24,6 @@ ENTRY(_text)
 
 jiffies = jiffies_64;
 
-
-#define HYPERVISOR_EXTABLE					\
-	. = ALIGN(SZ_8);					\
-	__start___kvm_ex_table = .;				\
-	*(__kvm_ex_table)					\
-	__stop___kvm_ex_table = .;
-
 #define HYPERVISOR_TEXT					\
 	/*						\
 	 * Align to 4 KB so that			\
@@ -46,7 +39,6 @@ jiffies = jiffies_64;
 	__hyp_idmap_text_end = .;			\
 	__hyp_text_start = .;				\
 	*(.hyp.text)					\
-	HYPERVISOR_EXTABLE				\
 	__hyp_text_end = .;
 
 #define IDMAP_TEXT					\

arch/arm64/kvm/hyp/entry.S

@@ -164,22 +164,18 @@ 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)
 
-	// restore the EL1 exception context so that we can report some
-	// information. Merge the exception code with the SError pending 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
 	msr	elr_el2, x2
 	msr	esr_el2, x3
 	msr	spsr_el2, x4

arch/arm64/kvm/hyp/hyp-entry.S

@@ -26,30 +26,6 @@
 #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
 	.pushsection	.hyp.text, "ax"
 
@@ -209,14 +185,27 @@ el2_sync:
 
 
 el2_error:
-	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
+	ldp	x0, x1, [sp], #16
 
+	/*
+	 * 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
 

arch/arm64/kvm/hyp/switch.c

@@ -25,7 +25,6 @@
 
 #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>
@@ -37,9 +36,6 @@
 #include <asm/processor.h>
 #include <asm/thread_info.h>
 
-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 bool __hyp_text update_fp_enabled(struct kvm_vcpu *vcpu)
 {
@@ -730,30 +726,3 @@ void __hyp_text __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)
 
 	unreachable();
 }
-
-asmlinkage void __hyp_text 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_cpu_state);
-
-	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);
-}