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@arm.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org --- 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