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 <[email protected]> Cc: Catalin Marinas <[email protected]> Cc: Will Deacon <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Dave Martin <[email protected]> --- arch/arm64/include/asm/processor.h | 3 +++ arch/arm64/include/asm/ptrace.h | 14 +++++++++++--- arch/arm64/kernel/asm-offsets.c | 1 + arch/arm64/kernel/entry.S | 14 ++++++++++++++ arch/arm64/kernel/process.c | 6 ++++++ 5 files changed, 35 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index 6b0d4df..27c5618 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -168,6 +168,9 @@ 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, diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h index 05cf913..43e5df5 100644 --- a/arch/arm64/include/asm/ptrace.h +++ b/arch/arm64/include/asm/ptrace.h @@ -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 interrupts_enabled(regs) \ - (!((regs)->pstate & PSR_I_BIT)) +#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) && irqs_priority_unmasked(regs)) #define fast_interrupts_enabled(regs) \ (!((regs)->pstate & PSR_F_BIT)) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index 323aeb5..bab4122 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -78,6 +78,7 @@ int main(void) DEFINE(S_ORIG_X0, offsetof(struct pt_regs, orig_x0)); 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(); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 039144e..2804c81 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -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 diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index d9a4c2d..34f495b 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -231,6 +231,9 @@ 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) { @@ -362,6 +365,9 @@ 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; } -- 1.9.1
