POR_EL0 is a register that can be modified by userspace directly,
so it must be context switched.
Signed-off-by: Joey Gouly <joey.gouly@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/asm/processor.h | 1 +
arch/arm64/include/asm/sysreg.h | 3 +++
arch/arm64/kernel/process.c | 16 ++++++++++++++++
3 files changed, 20 insertions(+)
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index e5bc54522e71..b3ad719c2d0c 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -179,6 +179,7 @@ struct thread_struct {
u64 sctlr_user;
u64 svcr;
u64 tpidr2_el0;
+ u64 por_el0;
};
static inline unsigned int thread_get_vl(struct thread_struct *thread,
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index cc2d61fd45c3..0dc8ee423af4 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -1007,6 +1007,9 @@
#define POE_RXW UL(0x7)
#define POE_MASK UL(0xf)
+/* Initial value for Permission Overlay Extension for EL0 */
+#define POR_EL0_INIT UL(0x7)
+
#define ARM64_FEATURE_FIELD_BITS 4
/* Defined for compatibility only, do not add new users. */
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 0fcc4eb1a7ab..d33f9717bfcd 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -271,12 +271,19 @@ static void flush_tagged_addr_state(void)
clear_thread_flag(TIF_TAGGED_ADDR);
}
+static void flush_poe(void)
+{
+ if (cpus_have_final_cap(ARM64_HAS_S1POE))
+ write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0);
+}
+
void flush_thread(void)
{
fpsimd_flush_thread();
tls_thread_flush();
flush_ptrace_hw_breakpoint(current);
flush_tagged_addr_state();
+ flush_poe();
}
void arch_release_task_struct(struct task_struct *tsk)
@@ -498,6 +505,14 @@ static void erratum_1418040_new_exec(void)
preempt_enable();
}
+static void permission_overlay_switch(struct task_struct *next)
+{
+ if (alternative_has_cap_unlikely(ARM64_HAS_S1POE)) {
+ current->thread.por_el0 = read_sysreg_s(SYS_POR_EL0);
+ write_sysreg_s(next->thread.por_el0, SYS_POR_EL0);
+ }
+}
+
/*
* __switch_to() checks current->thread.sctlr_user as an optimisation. Therefore
* this function must be called with preemption disabled and the update to
@@ -533,6 +548,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
ssbs_thread_switch(next);
erratum_1418040_thread_switch(next);
ptrauth_thread_switch_user(next);
+ permission_overlay_switch(next);
/*
* Complete any pending TLB or cache maintenance on this CPU in case
--
2.25.1
