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 Reviewed-by: Catalin Marinas catalin.marinas@arm.com --- arch/arm64/include/asm/cpufeature.h | 6 ++++++ arch/arm64/include/asm/processor.h | 1 + arch/arm64/include/asm/sysreg.h | 3 +++ arch/arm64/kernel/process.c | 28 ++++++++++++++++++++++++++++ 4 files changed, 38 insertions(+)
diff --git arch/arm64/include/asm/cpufeature.h arch/arm64/include/asm/cpufeature.h index 558434267271..3d261cc123c1 100644 --- arch/arm64/include/asm/cpufeature.h +++ arch/arm64/include/asm/cpufeature.h @@ -832,6 +832,12 @@ static inline bool system_supports_lpa2(void) return cpus_have_final_cap(ARM64_HAS_LPA2); }
+static inline bool system_supports_poe(void) +{ + return IS_ENABLED(CONFIG_ARM64_POE) && + alternative_has_cap_unlikely(ARM64_HAS_S1POE); +} + int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt); bool try_emulate_mrs(struct pt_regs *regs, u32 isn);
diff --git arch/arm64/include/asm/processor.h arch/arm64/include/asm/processor.h index f77371232d8c..e6376f979273 100644 --- arch/arm64/include/asm/processor.h +++ arch/arm64/include/asm/processor.h @@ -184,6 +184,7 @@ 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 arch/arm64/include/asm/sysreg.h arch/arm64/include/asm/sysreg.h index 4a9ea103817e..494e9efd856f 100644 --- arch/arm64/include/asm/sysreg.h +++ arch/arm64/include/asm/sysreg.h @@ -1077,6 +1077,9 @@ #define POE_RXW UL(0x7) #define POE_MASK UL(0xf)
+/* Initial value for Permission Overlay Extension for EL0 */ +#define POR_EL0_INIT POE_RXW + #define ARM64_FEATURE_FIELD_BITS 4
/* Defined for compatibility only, do not add new users. */ diff --git arch/arm64/kernel/process.c arch/arm64/kernel/process.c index 4ae31b7af6c3..a3a61ecdb165 100644 --- arch/arm64/kernel/process.c +++ arch/arm64/kernel/process.c @@ -271,12 +271,23 @@ static void flush_tagged_addr_state(void) clear_thread_flag(TIF_TAGGED_ADDR); }
+static void flush_poe(void) +{ + if (!system_supports_poe()) + return; + + write_sysreg_s(POR_EL0_INIT, SYS_POR_EL0); + /* ISB required for kernel uaccess routines when changing POR_EL0 */ + isb(); +} + 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) @@ -371,6 +382,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) if (system_supports_tpidr2()) p->thread.tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0);
+ if (system_supports_poe()) + p->thread.por_el0 = read_sysreg_s(SYS_POR_EL0); + if (stack_start) { if (is_compat_thread(task_thread_info(p))) childregs->compat_sp = stack_start; @@ -495,6 +509,19 @@ static void erratum_1418040_new_exec(void) preempt_enable(); }
+static void permission_overlay_switch(struct task_struct *next) +{ + if (!system_supports_poe()) + return; + + current->thread.por_el0 = read_sysreg_s(SYS_POR_EL0); + if (current->thread.por_el0 != next->thread.por_el0) { + write_sysreg_s(next->thread.por_el0, SYS_POR_EL0); + /* ISB required for kernel uaccess routines when chaning POR_EL0 */ + isb(); + } +} + /* * __switch_to() checks current->thread.sctlr_user as an optimisation. Therefore * this function must be called with preemption disabled and the update to @@ -530,6 +557,7 @@ 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