[PATCH 14/17] arm64: add __nocfi to functions that jump to a physical address

Sami Tolvanen
2021-03-12T00:50:51Z

Disable CFI checking for functions that switch to linear mapping and
make an indirect call to a physical address, since the compiler only
understands virtual addresses and the CFI check for such indirect calls
would always fail.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
arch/arm64/include/asm/mmu_context.h | 2 +-
arch/arm64/kernel/cpu-reset.h | 8 ++++----
arch/arm64/kernel/cpufeature.c | 2 +-
3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 519d535532be..27f3797baa2e 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -136,7 +136,7 @@ static inline void cpu_install_idmap(void)
* Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
* avoiding the possibility of conflicting TLB entries being allocated.
*/
-static inline void cpu_replace_ttbr1(pgd_t *pgdp)
+static inline void __nocfi cpu_replace_ttbr1(pgd_t *pgdp)
{
typedef void (ttbr_replace_func)(phys_addr_t);
extern ttbr_replace_func idmap_cpu_replace_ttbr1;
diff --git a/arch/arm64/kernel/cpu-reset.h b/arch/arm64/kernel/cpu-reset.h
index dfba8cf921e5..a05bda363272 100644
--- a/arch/arm64/kernel/cpu-reset.h
+++ b/arch/arm64/kernel/cpu-reset.h
@@ -13,10 +13,10 @@
void __cpu_soft_restart(unsigned long el2_switch, unsigned long entry,
unsigned long arg0, unsigned long arg1, unsigned long arg2);

-static inline void __noreturn cpu_soft_restart(unsigned long entry,
- unsigned long arg0,
- unsigned long arg1,
- unsigned long arg2)
+static inline void __noreturn __nocfi cpu_soft_restart(unsigned long entry,
+ unsigned long arg0,
+ unsigned long arg1,
+ unsigned long arg2)
{
typeof(__cpu_soft_restart) *restart;

diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 7ec1c2ccdc0b..473212ff4d70 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1443,7 +1443,7 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
}

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
-static void
+static void __nocfi
kpti_install_ng_mappings(const struct arm64_cpu_capabilities *__unused)
{
typedef void (kpti_remap_fn)(int, int, phys_addr_t);
--
2.31.0.rc2.261.g7f71774620-goog