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arm64: Make PMR part of task context

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In order to replace PSR.I interrupt disabling/enabling with ICC_PMR_EL1
interrupt masking, ICC_PMR_EL1 needs to be saved/restored when
taking/returning from an exception. This mimics the way hardware saves
and restores PSR.I bit in spsr_el1 for exceptions and ERET.

Add PMR to the registers to save in the pt_regs struct upon kernel entry,
and restore it before ERET. Also, initialize it to a sane value when
creating new tasks.

Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Julien Thierry 2019-01-31 14:58:46 +00:00 committed by Catalin Marinas
parent cdbc81ddef
commit 133d051863
5 changed files with 35 additions and 3 deletions
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3
arch/arm64/include/asm/processor.h
View File

@ -191,6 +191,9 @@ static inline void start_thread_common(struct pt_regs *regs, unsigned long pc)
memset(regs, 0, sizeof(*regs));
forget_syscall(regs);
regs->pc = pc;
if (system_uses_irq_prio_masking())
regs->pmr_save = GIC_PRIO_IRQON;
}
static inline void start_thread(struct pt_regs *regs, unsigned long pc,

12
arch/arm64/include/asm/ptrace.h
View File

@ -19,6 +19,8 @@
#ifndef __ASM_PTRACE_H
#define __ASM_PTRACE_H
#include <asm/cpufeature.h>
#include <uapi/asm/ptrace.h>
/* Current Exception Level values, as contained in CurrentEL */
@ -179,7 +181,8 @@ struct pt_regs {
#endif
u64 orig_addr_limit;
u64 unused; // maintain 16 byte alignment
/* Only valid when ARM64_HAS_IRQ_PRIO_MASKING is enabled. */
u64 pmr_save;
u64 stackframe[2];
};
@ -214,8 +217,13 @@ static inline void forget_syscall(struct pt_regs *regs)
#define processor_mode(regs) \
((regs)->pstate & PSR_MODE_MASK)
#define irqs_priority_unmasked(regs) \
(system_uses_irq_prio_masking() ? \
(regs)->pmr_save == GIC_PRIO_IRQON : \
true)
#define interrupts_enabled(regs) \
(!((regs)->pstate & PSR_I_BIT))
(!((regs)->pstate & PSR_I_BIT) && irqs_priority_unmasked(regs))
#define fast_interrupts_enabled(regs) \
(!((regs)->pstate & PSR_F_BIT))

1
arch/arm64/kernel/asm-offsets.c
View File

@ -73,6 +73,7 @@ int main(void)
DEFINE(S_PC, offsetof(struct pt_regs, pc));
DEFINE(S_SYSCALLNO, offsetof(struct pt_regs, syscallno));
DEFINE(S_ORIG_ADDR_LIMIT, offsetof(struct pt_regs, orig_addr_limit));
DEFINE(S_PMR_SAVE, offsetof(struct pt_regs, pmr_save));
DEFINE(S_STACKFRAME, offsetof(struct pt_regs, stackframe));
DEFINE(S_FRAME_SIZE, sizeof(struct pt_regs));
BLANK();

14
arch/arm64/kernel/entry.S
View File

@ -249,6 +249,12 @@ alternative_else_nop_endif
msr sp_el0, tsk
.endif
/* Save pmr */
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
mrs_s x20, SYS_ICC_PMR_EL1
str x20, [sp, #S_PMR_SAVE]
alternative_else_nop_endif
/*
* Registers that may be useful after this macro is invoked:
*
@ -269,6 +275,14 @@ alternative_else_nop_endif
/* No need to restore UAO, it will be restored from SPSR_EL1 */
.endif
/* Restore pmr */
alternative_if ARM64_HAS_IRQ_PRIO_MASKING
ldr x20, [sp, #S_PMR_SAVE]
msr_s SYS_ICC_PMR_EL1, x20
/* Ensure priority change is seen by redistributor */
dsb sy
alternative_else_nop_endif
ldp x21, x22, [sp, #S_PC] // load ELR, SPSR
.if \el == 0
ct_user_enter

6
arch/arm64/kernel/process.c
View File

@ -232,6 +232,9 @@ void __show_regs(struct pt_regs *regs)
printk("sp : %016llx\n", sp);
if (system_uses_irq_prio_masking())
printk("pmr_save: %08llx\n", regs->pmr_save);
i = top_reg;
while (i >= 0) {
@ -363,6 +366,9 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
if (arm64_get_ssbd_state() == ARM64_SSBD_FORCE_DISABLE)
childregs->pstate |= PSR_SSBS_BIT;
if (system_uses_irq_prio_masking())
childregs->pmr_save = GIC_PRIO_IRQON;
p->thread.cpu_context.x19 = stack_start;
p->thread.cpu_context.x20 = stk_sz;
}