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Code

arm64: context switch POR_EL0 register

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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>
Link: https://lore.kernel.org/r/20240822151113.1479789-7-joey.gouly@arm.com
[will: Dropped unnecessary isb()s]
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Joey Gouly 2024-08-22 16:10:49 +01:00 committed by Will Deacon
parent 3496f69391
commit 160a8e13de
4 changed files with 34 additions and 0 deletions
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6
arch/arm64/include/asm/cpufeature.h
View File

@ -832,6 +832,12 @@ static inline bool system_supports_lpa2(void)
return cpus_have_final_cap(ARM64_HAS_LPA2); 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); int do_emulate_mrs(struct pt_regs *regs, u32 sys_reg, u32 rt);
bool try_emulate_mrs(struct pt_regs *regs, u32 isn); bool try_emulate_mrs(struct pt_regs *regs, u32 isn);

1
arch/arm64/include/asm/processor.h
View File

@ -184,6 +184,7 @@ struct thread_struct {
u64 sctlr_user; u64 sctlr_user;
u64 svcr; u64 svcr;
u64 tpidr2_el0; u64 tpidr2_el0;
u64 por_el0;
}; };
static inline unsigned int thread_get_vl(struct thread_struct *thread, static inline unsigned int thread_get_vl(struct thread_struct *thread,

3
arch/arm64/include/asm/sysreg.h
View File

@ -1077,6 +1077,9 @@
#define POE_RXW UL(0x7) #define POE_RXW UL(0x7)
#define POE_MASK UL(0xf) #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 #define ARM64_FEATURE_FIELD_BITS 4
/* Defined for compatibility only, do not add new users. */ /* Defined for compatibility only, do not add new users. */

24
arch/arm64/kernel/process.c
View File

@ -271,12 +271,21 @@ static void flush_tagged_addr_state(void)
clear_thread_flag(TIF_TAGGED_ADDR); 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);
}
void flush_thread(void) void flush_thread(void)
{ {
fpsimd_flush_thread(); fpsimd_flush_thread();
tls_thread_flush(); tls_thread_flush();
flush_ptrace_hw_breakpoint(current); flush_ptrace_hw_breakpoint(current);
flush_tagged_addr_state(); flush_tagged_addr_state();
flush_poe();
} }
void arch_release_task_struct(struct task_struct *tsk) void arch_release_task_struct(struct task_struct *tsk)
@ -371,6 +380,9 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
if (system_supports_tpidr2()) if (system_supports_tpidr2())
p->thread.tpidr2_el0 = read_sysreg_s(SYS_TPIDR2_EL0); 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 (stack_start) {
if (is_compat_thread(task_thread_info(p))) if (is_compat_thread(task_thread_info(p)))
childregs->compat_sp = stack_start; childregs->compat_sp = stack_start;
@ -495,6 +507,17 @@ static void erratum_1418040_new_exec(void)
preempt_enable(); 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);
}
}
/* /*
* __switch_to() checks current->thread.sctlr_user as an optimisation. Therefore * __switch_to() checks current->thread.sctlr_user as an optimisation. Therefore
* this function must be called with preemption disabled and the update to * this function must be called with preemption disabled and the update to
@ -530,6 +553,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
ssbs_thread_switch(next); ssbs_thread_switch(next);
erratum_1418040_thread_switch(next); erratum_1418040_thread_switch(next);
ptrauth_thread_switch_user(next); ptrauth_thread_switch_user(next);
permission_overlay_switch(next);
/* /*
* Complete any pending TLB or cache maintenance on this CPU in case * Complete any pending TLB or cache maintenance on this CPU in case