diff options
| author | Pierre-Clément Tosi <ptosi@google.com> | 2024-06-10 07:32:37 +0100 |
|---|---|---|
| committer | Oliver Upton <oliver.upton@linux.dev> | 2024-06-20 17:40:54 +0000 |
| commit | eca4ba5b6dff9b6ec03c9607ac297076f037fcfc (patch) | |
| tree | 7f3e8f00b91a8e29727587f93c78ebc5d0fca85f /arch/arm64/kvm | |
| parent | 8f3873a39529101213fa1109d499239d57185551 (diff) | |
KVM: arm64: nVHE: Support CONFIG_CFI_CLANG at EL2
The compiler implements kCFI by adding type information (u32) above
every function that might be indirectly called and, whenever a function
pointer is called, injects a read-and-compare of that u32 against the
value corresponding to the expected type. In case of a mismatch, a BRK
instruction gets executed. When the hypervisor triggers such an
exception in nVHE, it panics and triggers and exception return to EL1.
Therefore, teach nvhe_hyp_panic_handler() to detect kCFI errors from the
ESR and report them. If necessary, remind the user that EL2 kCFI is not
affected by CONFIG_CFI_PERMISSIVE.
Pass $(CC_FLAGS_CFI) to the compiler when building the nVHE hyp code.
Use SYM_TYPED_FUNC_START() for __pkvm_init_switch_pgd, as nVHE can't
call it directly and must use a PA function pointer from C (because it
is part of the idmap page), which would trigger a kCFI failure if the
type ID wasn't present.
Signed-off-by: Pierre-Clément Tosi <ptosi@google.com>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20240610063244.2828978-9-ptosi@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Diffstat (limited to 'arch/arm64/kvm')
| -rw-r--r-- | arch/arm64/kvm/handle_exit.c | 10 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/Makefile | 6 | ||||
| -rw-r--r-- | arch/arm64/kvm/hyp/nvhe/hyp-init.S | 6 |
3 files changed, 18 insertions, 4 deletions
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c index b3d6657a259d..69b08ac7322d 100644 --- a/arch/arm64/kvm/handle_exit.c +++ b/arch/arm64/kvm/handle_exit.c @@ -417,6 +417,14 @@ static void print_nvhe_hyp_panic(const char *name, u64 panic_addr) (void *)(panic_addr + kaslr_offset())); } +static void kvm_nvhe_report_cfi_failure(u64 panic_addr) +{ + print_nvhe_hyp_panic("CFI failure", panic_addr); + + if (IS_ENABLED(CONFIG_CFI_PERMISSIVE)) + kvm_err(" (CONFIG_CFI_PERMISSIVE ignored for hyp failures)\n"); +} + void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr, u64 elr_virt, u64 elr_phys, u64 par, uintptr_t vcpu, @@ -446,6 +454,8 @@ void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr, kvm_err("nVHE hyp BUG at: %s:%u!\n", file, line); else print_nvhe_hyp_panic("BUG", panic_addr); + } else if (IS_ENABLED(CONFIG_CFI_CLANG) && esr_is_cfi_brk(esr)) { + kvm_nvhe_report_cfi_failure(panic_addr); } else { print_nvhe_hyp_panic("panic", panic_addr); } diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile index 50fa0ffb6b7e..782b34b004be 100644 --- a/arch/arm64/kvm/hyp/nvhe/Makefile +++ b/arch/arm64/kvm/hyp/nvhe/Makefile @@ -89,9 +89,9 @@ quiet_cmd_hyprel = HYPREL $@ quiet_cmd_hypcopy = HYPCOPY $@ cmd_hypcopy = $(OBJCOPY) --prefix-symbols=__kvm_nvhe_ $< $@ -# Remove ftrace, Shadow Call Stack, and CFI CFLAGS. -# This is equivalent to the 'notrace', '__noscs', and '__nocfi' annotations. -KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_CFI), $(KBUILD_CFLAGS)) +# Remove ftrace and Shadow Call Stack CFLAGS. +# This is equivalent to the 'notrace' and '__noscs' annotations. +KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS), $(KBUILD_CFLAGS)) # Starting from 13.0.0 llvm emits SHT_REL section '.llvm.call-graph-profile' # when profile optimization is applied. gen-hyprel does not support SHT_REL and # causes a build failure. Remove profile optimization flags. diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S index 3a2836a52e85..07120b37da35 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S @@ -5,6 +5,7 @@ */ #include <linux/arm-smccc.h> +#include <linux/cfi_types.h> #include <linux/linkage.h> #include <asm/alternative.h> @@ -268,8 +269,11 @@ SYM_CODE_END(__kvm_handle_stub_hvc) /* * void __pkvm_init_switch_pgd(phys_addr_t pgd, unsigned long sp, * void (*fn)(void)); + * + * SYM_TYPED_FUNC_START() allows C to call this ID-mapped function indirectly + * using a physical pointer without triggering a kCFI failure. */ -SYM_FUNC_START(__pkvm_init_switch_pgd) +SYM_TYPED_FUNC_START(__pkvm_init_switch_pgd) /* Turn the MMU off */ pre_disable_mmu_workaround mrs x3, sctlr_el2 |