On Mon, 21 Jan 2019 at 16:34, Julien Thierry <[email protected]> wrote: > > Instead disabling interrupts by setting the PSR.I bit, use a priority > higher than the one used for interrupts to mask them via PMR. > > When using PMR to disable interrupts, the value of PMR will be used > instead of PSR.[DAIF] for the irqflags. > > Signed-off-by: Julien Thierry <[email protected]> > Suggested-by: Daniel Thompson <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Ard Biesheuvel <[email protected]> > Cc: Oleg Nesterov <[email protected]> > --- > arch/arm64/include/asm/efi.h | 6 +++ > arch/arm64/include/asm/irqflags.h | 104 > ++++++++++++++++++++++++++++---------- > 2 files changed, 82 insertions(+), 28 deletions(-) > > diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h > index 7ed3208..3db6772 100644 > --- a/arch/arm64/include/asm/efi.h > +++ b/arch/arm64/include/asm/efi.h > @@ -44,6 +44,12 @@ > > #define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | > PSR_F_BIT) > > +#define arch_efi_save_flags(state_flags) \ > + ((void)((state_flags) = read_sysreg(daif))) > + > +#define arch_efi_restore_flags(state_flags) write_sysreg(state_flags, > daif) > + > + > /* arch specific definitions used by the stub code */ > > /*
For the EFI changes Acked-by: Ard Biesheuvel <[email protected]> although it deserves a comment as to why it is unaffected by ARM64_HAS_IRQ_PRIO_MASKING > diff --git a/arch/arm64/include/asm/irqflags.h > b/arch/arm64/include/asm/irqflags.h > index 24692ed..7e82a92 100644 > --- a/arch/arm64/include/asm/irqflags.h > +++ b/arch/arm64/include/asm/irqflags.h > @@ -18,7 +18,9 @@ > > #ifdef __KERNEL__ > > +#include <asm/alternative.h> > #include <asm/ptrace.h> > +#include <asm/sysreg.h> > > /* > * Aarch64 has flags for masking: Debug, Asynchronous (serror), Interrupts > and > @@ -36,33 +38,31 @@ > /* > * CPU interrupt mask handling. > */ > -static inline unsigned long arch_local_irq_save(void) > -{ > - unsigned long flags; > - asm volatile( > - "mrs %0, daif // arch_local_irq_save\n" > - "msr daifset, #2" > - : "=r" (flags) > - : > - : "memory"); > - return flags; > -} > - > static inline void arch_local_irq_enable(void) > { > - asm volatile( > - "msr daifclr, #2 // arch_local_irq_enable" > - : > + unsigned long unmasked = GIC_PRIO_IRQON; > + > + asm volatile(ALTERNATIVE( > + "msr daifclr, #2 // arch_local_irq_enable\n" > + "nop", > + "msr_s " __stringify(SYS_ICC_PMR_EL1) ",%0\n" > + "dsb sy", > + ARM64_HAS_IRQ_PRIO_MASKING) > : > + : "r" (unmasked) > : "memory"); > } > > static inline void arch_local_irq_disable(void) > { > - asm volatile( > - "msr daifset, #2 // arch_local_irq_disable" > - : > + unsigned long masked = GIC_PRIO_IRQOFF; > + > + asm volatile(ALTERNATIVE( > + "msr daifset, #2 // arch_local_irq_disable", > + "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0", > + ARM64_HAS_IRQ_PRIO_MASKING) > : > + : "r" (masked) > : "memory"); > } > > @@ -71,12 +71,44 @@ static inline void arch_local_irq_disable(void) > */ > static inline unsigned long arch_local_save_flags(void) > { > + unsigned long daif_bits; > unsigned long flags; > - asm volatile( > - "mrs %0, daif // arch_local_save_flags" > - : "=r" (flags) > - : > + > + daif_bits = read_sysreg(daif); > + > + /* > + * The asm is logically equivalent to: > + * > + * if (system_uses_irq_prio_masking()) > + * flags = (daif_bits & PSR_I_BIT) ? > + * GIC_PRIO_IRQOFF : > + * read_sysreg_s(SYS_ICC_PMR_EL1); > + * else > + * flags = daif_bits; > + */ > + asm volatile(ALTERNATIVE( > + "mov %0, %1\n" > + "nop\n" > + "nop", > + "mrs_s %0, " __stringify(SYS_ICC_PMR_EL1) "\n" > + "ands %1, %1, " __stringify(PSR_I_BIT) "\n" > + "csel %0, %0, %2, eq", > + ARM64_HAS_IRQ_PRIO_MASKING) > + : "=&r" (flags), "+r" (daif_bits) > + : "r" (GIC_PRIO_IRQOFF) > : "memory"); > + > + return flags; > +} > + > +static inline unsigned long arch_local_irq_save(void) > +{ > + unsigned long flags; > + > + flags = arch_local_save_flags(); > + > + arch_local_irq_disable(); > + > return flags; > } > > @@ -85,16 +117,32 @@ static inline unsigned long arch_local_save_flags(void) > */ > static inline void arch_local_irq_restore(unsigned long flags) > { > - asm volatile( > - "msr daif, %0 // arch_local_irq_restore" > - : > - : "r" (flags) > - : "memory"); > + asm volatile(ALTERNATIVE( > + "msr daif, %0\n" > + "nop", > + "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %0\n" > + "dsb sy", > + ARM64_HAS_IRQ_PRIO_MASKING) > + : "+r" (flags) > + : > + : "memory"); > } > > static inline int arch_irqs_disabled_flags(unsigned long flags) > { > - return flags & PSR_I_BIT; > + int res; > + > + asm volatile(ALTERNATIVE( > + "and %w0, %w1, #" __stringify(PSR_I_BIT) "\n" > + "nop", > + "cmp %w1, #" __stringify(GIC_PRIO_IRQOFF) "\n" > + "cset %w0, ls", > + ARM64_HAS_IRQ_PRIO_MASKING) > + : "=&r" (res) > + : "r" ((int) flags) > + : "memory"); > + > + return res; > } > #endif > #endif > -- > 1.9.1 >
