lkml.org 
[lkml]   [2018]   [Aug]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v5 15/27] arm64: irqflags: Use ICC_PMR_EL1 for interrupt masking
Date
Instead disabling interrupts by setting the PSR.I bit, use a priority
higher than the one used for interrupts to mask them via PMR.

The value chosen for PMR to enable/disable interrupts encodes the status
of interrupts on a single bit. This information is stored in the irqflags
values used when saving/restoring IRQ status.

Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Suggested-by: Daniel Thompson <daniel.thompson@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Oleg Nesterov <oleg@redhat.com>
---
arch/arm64/include/asm/assembler.h | 17 ++++++-
arch/arm64/include/asm/efi.h | 3 +-
arch/arm64/include/asm/irqflags.h | 97 ++++++++++++++++++++++++++++++--------
arch/arm64/include/asm/ptrace.h | 10 ++--
arch/arm64/kernel/entry.S | 2 +-
5 files changed, 102 insertions(+), 27 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index 0bcc98d..0b2dcfd 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -23,6 +23,7 @@
#ifndef __ASM_ASSEMBLER_H
#define __ASM_ASSEMBLER_H

+#include <asm/alternative.h>
#include <asm/asm-offsets.h>
#include <asm/cpufeature.h>
#include <asm/debug-monitors.h>
@@ -62,12 +63,24 @@
/*
* Enable and disable interrupts.
*/
- .macro disable_irq
+ .macro disable_irq, tmp
+ mov \tmp, #ICC_PMR_EL1_MASKED
+alternative_if_not ARM64_HAS_IRQ_PRIO_MASKING
msr daifset, #2
+alternative_else
+ msr_s SYS_ICC_PMR_EL1, \tmp
+alternative_endif
.endm

- .macro enable_irq
+ .macro enable_irq, tmp
+ mov \tmp, #ICC_PMR_EL1_UNMASKED
+alternative_if_not ARM64_HAS_IRQ_PRIO_MASKING
msr daifclr, #2
+ nop
+alternative_else
+ msr_s SYS_ICC_PMR_EL1, \tmp
+ dsb sy
+alternative_endif
.endm

.macro save_and_disable_irq, flags
diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 7ed3208..3e06891 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -42,7 +42,8 @@

efi_status_t __efi_rt_asm_wrapper(void *, const char *, ...);

-#define ARCH_EFI_IRQ_FLAGS_MASK (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT)
+#define ARCH_EFI_IRQ_FLAGS_MASK \
+ (PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT | ARCH_FLAG_PMR_EN)

/* arch specific definitions used by the stub code */

diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h
index 24692ed..193cfd0 100644
--- a/arch/arm64/include/asm/irqflags.h
+++ b/arch/arm64/include/asm/irqflags.h
@@ -18,7 +18,27 @@

#ifdef __KERNEL__

+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
#include <asm/ptrace.h>
+#include <asm/sysreg.h>
+
+
+/*
+ * When ICC_PMR_EL1 is used for interrupt masking, only the bit indicating
+ * whether the normal interrupts are masked is kept along with the daif
+ * flags.
+ */
+#define ARCH_FLAG_PMR_EN 0x1
+
+#define MAKE_ARCH_FLAGS(daif, pmr) \
+ ((daif) | (((pmr) >> ICC_PMR_EL1_EN_SHIFT) & ARCH_FLAG_PMR_EN))
+
+#define ARCH_FLAGS_GET_PMR(flags) \
+ ((((flags) & ARCH_FLAG_PMR_EN) << ICC_PMR_EL1_EN_SHIFT) \
+ | ICC_PMR_EL1_MASKED)
+
+#define ARCH_FLAGS_GET_DAIF(flags) ((flags) & ~ARCH_FLAG_PMR_EN)

/*
* Aarch64 has flags for masking: Debug, Asynchronous (serror), Interrupts and
@@ -38,31 +58,50 @@
*/
static inline unsigned long arch_local_irq_save(void)
{
- unsigned long flags;
- asm volatile(
+ unsigned long flags, masked = ICC_PMR_EL1_MASKED;
+ unsigned long pmr = 0;
+
+ asm volatile(ALTERNATIVE(
"mrs %0, daif // arch_local_irq_save\n"
- "msr daifset, #2"
- : "=r" (flags)
- :
+ "msr daifset, #2\n"
+ "mov %1, #" __stringify(ICC_PMR_EL1_UNMASKED),
+ /* --- */
+ "mrs %0, daif\n"
+ "mrs_s %1, " __stringify(SYS_ICC_PMR_EL1) "\n"
+ "msr_s " __stringify(SYS_ICC_PMR_EL1) ", %2",
+ ARM64_HAS_IRQ_PRIO_MASKING)
+ : "=&r" (flags), "=&r" (pmr)
+ : "r" (masked)
: "memory");
- return flags;
+
+ return MAKE_ARCH_FLAGS(flags, pmr);
}

static inline void arch_local_irq_enable(void)
{
- asm volatile(
- "msr daifclr, #2 // arch_local_irq_enable"
- :
+ unsigned long unmasked = ICC_PMR_EL1_UNMASKED;
+
+ 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 = ICC_PMR_EL1_MASKED;
+
+ 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");
}

@@ -72,12 +111,19 @@ static inline void arch_local_irq_disable(void)
static inline unsigned long arch_local_save_flags(void)
{
unsigned long flags;
- asm volatile(
- "mrs %0, daif // arch_local_save_flags"
- : "=r" (flags)
+ unsigned long pmr = 0;
+
+ asm volatile(ALTERNATIVE(
+ "mrs %0, daif // arch_local_save_flags\n"
+ "mov %1, #" __stringify(ICC_PMR_EL1_UNMASKED),
+ "mrs %0, daif\n"
+ "mrs_s %1, " __stringify(SYS_ICC_PMR_EL1),
+ ARM64_HAS_IRQ_PRIO_MASKING)
+ : "=r" (flags), "=r" (pmr)
:
: "memory");
- return flags;
+
+ return MAKE_ARCH_FLAGS(flags, pmr);
}

/*
@@ -85,16 +131,27 @@ 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"
+ unsigned long pmr = ARCH_FLAGS_GET_PMR(flags);
+
+ flags = ARCH_FLAGS_GET_DAIF(flags);
+
+ asm volatile(ALTERNATIVE(
+ "msr daif, %0 // arch_local_irq_restore\n"
+ "nop\n"
+ "nop",
+ "msr daif, %0\n"
+ "msr_s " __stringify(SYS_ICC_PMR_EL1) ",%1\n"
+ "dsb sy",
+ ARM64_HAS_IRQ_PRIO_MASKING)
:
- : "r" (flags)
+ : "r" (flags), "r" (pmr)
: "memory");
}

static inline int arch_irqs_disabled_flags(unsigned long flags)
{
- return flags & PSR_I_BIT;
+ return (ARCH_FLAGS_GET_DAIF(flags) & (PSR_I_BIT)) |
+ !(ARCH_FLAGS_GET_PMR(flags) & ICC_PMR_EL1_EN_BIT);
}
#endif
#endif
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 29ec217..67df46e 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -25,8 +25,11 @@
#define CurrentEL_EL1 (1 << 2)
#define CurrentEL_EL2 (2 << 2)

-/* PMR value use to unmask interrupts */
+/* PMR values used to mask/unmask interrupts */
#define ICC_PMR_EL1_UNMASKED 0xf0
+#define ICC_PMR_EL1_EN_SHIFT 6
+#define ICC_PMR_EL1_EN_BIT (1 << ICC_PMR_EL1_EN_SHIFT) // PMR IRQ enable
+#define ICC_PMR_EL1_MASKED (ICC_PMR_EL1_UNMASKED ^ ICC_PMR_EL1_EN_BIT)

/* AArch32-specific ptrace requests */
#define COMPAT_PTRACE_GETREGS 12
@@ -201,8 +204,9 @@ 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 interrupts_enabled(regs) \
+ ((!((regs)->pstate & PSR_I_BIT)) && \
+ ((regs)->pmr_save & ICC_PMR_EL1_EN_BIT))

#define fast_interrupts_enabled(regs) \
(!((regs)->pstate & PSR_F_BIT))
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 79b06af..91e1e3d 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -912,7 +912,7 @@ work_pending:
* "slow" syscall return path.
*/
ret_to_user:
- disable_irq // disable interrupts
+ disable_irq x21 // disable interrupts
ldr x1, [tsk, #TSK_TI_FLAGS]
and x2, x1, #_TIF_WORK_MASK
cbnz x2, work_pending
--
1.9.1
\
 
 \ /
  Last update: 2018-08-28 17:55    [W:0.366 / U:0.532 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site