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authorLinus Torvalds <torvalds@linux-foundation.org>2020-08-28 20:37:33 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2020-08-28 20:37:33 +0200
commit96d454cd2c1668010406ea4c28ab915bcbb747f4 (patch)
tree2d568bfdb4feb947731a38fd9785b4a71c7dca9d /arch
parentkernel.h: Silence sparse warning in lower_32_bits (diff)
parentKVM: arm64: Set HCR_EL2.PTW to prevent AT taking synchronous exception (diff)
downloadlinux-96d454cd2c1668010406ea4c28ab915bcbb747f4.tar.xz
linux-96d454cd2c1668010406ea4c28ab915bcbb747f4.zip
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
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/Makefile14
-rw-r--r--arch/arm64/include/asm/compiler.h6
-rw-r--r--arch/arm64/include/asm/kvm_arm.h3
-rw-r--r--arch/arm64/include/asm/kvm_asm.h43
-rw-r--r--arch/arm64/include/asm/tlbflush.h6
-rw-r--r--arch/arm64/kernel/image-vars.h4
-rw-r--r--arch/arm64/kernel/vmlinux.lds.S8
-rw-r--r--arch/arm64/kvm/hyp/entry.S15
-rw-r--r--arch/arm64/kvm/hyp/hyp-entry.S65
-rw-r--r--arch/arm64/kvm/hyp/include/hyp/switch.h39
-rw-r--r--arch/arm64/kvm/hyp/nvhe/switch.c5
-rw-r--r--arch/arm64/kvm/hyp/vhe/switch.c5
12 files changed, 172 insertions, 41 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index b45f0124cc16..130569f90c54 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -82,8 +82,8 @@ endif
# compiler to generate them and consequently to break the single image contract
# we pass it only to the assembler. This option is utilized only in case of non
# integrated assemblers.
-ifneq ($(CONFIG_AS_HAS_ARMV8_4), y)
-branch-prot-flags-$(CONFIG_AS_HAS_PAC) += -Wa,-march=armv8.3-a
+ifeq ($(CONFIG_AS_HAS_PAC), y)
+asm-arch := armv8.3-a
endif
endif
@@ -91,7 +91,12 @@ KBUILD_CFLAGS += $(branch-prot-flags-y)
ifeq ($(CONFIG_AS_HAS_ARMV8_4), y)
# make sure to pass the newest target architecture to -march.
-KBUILD_CFLAGS += -Wa,-march=armv8.4-a
+asm-arch := armv8.4-a
+endif
+
+ifdef asm-arch
+KBUILD_CFLAGS += -Wa,-march=$(asm-arch) \
+ -DARM64_ASM_ARCH='"$(asm-arch)"'
endif
ifeq ($(CONFIG_SHADOW_CALL_STACK), y)
@@ -165,7 +170,8 @@ zinstall install:
PHONY += vdso_install
vdso_install:
$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso $@
- $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@
+ $(if $(CONFIG_COMPAT_VDSO), \
+ $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 $@)
# We use MRPROPER_FILES and CLEAN_FILES now
archclean:
diff --git a/arch/arm64/include/asm/compiler.h b/arch/arm64/include/asm/compiler.h
index 51a7ce87cdfe..6fb2e6bcc392 100644
--- a/arch/arm64/include/asm/compiler.h
+++ b/arch/arm64/include/asm/compiler.h
@@ -2,6 +2,12 @@
#ifndef __ASM_COMPILER_H
#define __ASM_COMPILER_H
+#ifdef ARM64_ASM_ARCH
+#define ARM64_ASM_PREAMBLE ".arch " ARM64_ASM_ARCH "\n"
+#else
+#define ARM64_ASM_PREAMBLE
+#endif
+
/*
* The EL0/EL1 pointer bits used by a pointer authentication code.
* This is dependent on TBI0/TBI1 being enabled, or bits 63:56 would also apply.
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 51c1d9918999..1da8e3dc4455 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -71,11 +71,12 @@
* IMO: Override CPSR.I and enable signaling with VI
* FMO: Override CPSR.F and enable signaling with VF
* SWIO: Turn set/way invalidates into set/way clean+invalidate
+ * PTW: Take a stage2 fault if a stage1 walk steps in device memory
*/
#define HCR_GUEST_FLAGS (HCR_TSC | HCR_TSW | HCR_TWE | HCR_TWI | HCR_VM | \
HCR_BSU_IS | HCR_FB | HCR_TAC | \
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW | HCR_TLOR | \
- HCR_FMO | HCR_IMO)
+ HCR_FMO | HCR_IMO | HCR_PTW )
#define HCR_VIRT_EXCP_MASK (HCR_VSE | HCR_VI | HCR_VF)
#define HCR_HOST_NVHE_FLAGS (HCR_RW | HCR_API | HCR_APK)
#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index fb1a922b31ba..6f98fbd0ac81 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -169,6 +169,34 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
*__hyp_this_cpu_ptr(sym); \
})
+#define __KVM_EXTABLE(from, to) \
+ " .pushsection __kvm_ex_table, \"a\"\n" \
+ " .align 3\n" \
+ " .long (" #from " - .), (" #to " - .)\n" \
+ " .popsection\n"
+
+
+#define __kvm_at(at_op, addr) \
+( { \
+ int __kvm_at_err = 0; \
+ u64 spsr, elr; \
+ asm volatile( \
+ " mrs %1, spsr_el2\n" \
+ " mrs %2, elr_el2\n" \
+ "1: at "at_op", %3\n" \
+ " isb\n" \
+ " b 9f\n" \
+ "2: msr spsr_el2, %1\n" \
+ " msr elr_el2, %2\n" \
+ " mov %w0, %4\n" \
+ "9:\n" \
+ __KVM_EXTABLE(1b, 2b) \
+ : "+r" (__kvm_at_err), "=&r" (spsr), "=&r" (elr) \
+ : "r" (addr), "i" (-EFAULT)); \
+ __kvm_at_err; \
+} )
+
+
#else /* __ASSEMBLY__ */
.macro hyp_adr_this_cpu reg, sym, tmp
@@ -193,6 +221,21 @@ extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ];
ldr \vcpu, [\ctxt, #HOST_CONTEXT_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__ */
diff --git a/arch/arm64/include/asm/tlbflush.h b/arch/arm64/include/asm/tlbflush.h
index d493174415db..cc3f5a33ff9c 100644
--- a/arch/arm64/include/asm/tlbflush.h
+++ b/arch/arm64/include/asm/tlbflush.h
@@ -28,14 +28,16 @@
* not. The macros handles invoking the asm with or without the
* register argument as appropriate.
*/
-#define __TLBI_0(op, arg) asm ("tlbi " #op "\n" \
+#define __TLBI_0(op, arg) asm (ARM64_ASM_PREAMBLE \
+ "tlbi " #op "\n" \
ALTERNATIVE("nop\n nop", \
"dsb ish\n tlbi " #op, \
ARM64_WORKAROUND_REPEAT_TLBI, \
CONFIG_ARM64_WORKAROUND_REPEAT_TLBI) \
: : )
-#define __TLBI_1(op, arg) asm ("tlbi " #op ", %0\n" \
+#define __TLBI_1(op, arg) asm (ARM64_ASM_PREAMBLE \
+ "tlbi " #op ", %0\n" \
ALTERNATIVE("nop\n nop", \
"dsb ish\n tlbi " #op ", %0", \
ARM64_WORKAROUND_REPEAT_TLBI, \
diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
index 9e897c500237..8982b68289b7 100644
--- a/arch/arm64/kernel/image-vars.h
+++ b/arch/arm64/kernel/image-vars.h
@@ -103,6 +103,10 @@ KVM_NVHE_ALIAS(vgic_v3_cpuif_trap);
KVM_NVHE_ALIAS(gic_pmr_sync);
#endif
+/* EL2 exception handling */
+KVM_NVHE_ALIAS(__start___kvm_ex_table);
+KVM_NVHE_ALIAS(__stop___kvm_ex_table);
+
#endif /* CONFIG_KVM */
#endif /* __ARM64_KERNEL_IMAGE_VARS_H */
diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
index ec8e894684a7..7cba7623fcec 100644
--- a/arch/arm64/kernel/vmlinux.lds.S
+++ b/arch/arm64/kernel/vmlinux.lds.S
@@ -20,6 +20,13 @@ 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 \
@@ -35,6 +42,7 @@ jiffies = jiffies_64;
__hyp_idmap_text_end = .; \
__hyp_text_start = .; \
*(.hyp.text) \
+ HYPERVISOR_EXTABLE \
__hyp_text_end = .;
#define IDMAP_TEXT \
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();
+}