The hypervisor may not have full access to the kernel data structures
and hence cannot safely use cpus_have_cap() helper for checking the
system capability. Add a safe helper for hypervisors to check a constant
system capability, which *doesn't* fall back to checking the bitmap
maintained by the kernel. With this, make the cpus_have_cap() only
check the bitmask and force constant cap checks to use the new API
for quicker checks.
Cc: Robert Ritcher <rritc...@cavium.com>
Cc: Tirumalesh Chalamarla <tchalama...@cavium.com>
Cc: Marc Zyngier <marc.zyng...@arm.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poul...@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 19 ++++++++++++-------
arch/arm64/kernel/cpufeature.c | 2 +-
arch/arm64/kernel/process.c | 2 +-
drivers/irqchip/irq-gic-v3.c | 13 +------------
4 files changed, 15 insertions(+), 21 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h
b/arch/arm64/include/asm/cpufeature.h
index 0bc0b1d..9890d20 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -9,8 +9,6 @@
#ifndef __ASM_CPUFEATURE_H
#define __ASM_CPUFEATURE_H
-#include <linux/jump_label.h>
-
#include <asm/cpucaps.h>
#include <asm/hwcap.h>
#include <asm/sysreg.h>
@@ -27,6 +25,8 @@
#ifndef __ASSEMBLY__
+#include <linux/bug.h>
+#include <linux/jump_label.h>
#include <linux/kernel.h>
/* CPU feature register tracking */
@@ -104,14 +104,19 @@ static inline bool cpu_have_feature(unsigned int num)
return elf_hwcap & (1UL << num);
}
+/* System capability check for constant caps */
+static inline bool cpus_have_const_cap(int num)
+{
+ if (num >= ARM64_NCAPS)
+ return false;
+ return static_branch_unlikely(&cpu_hwcap_keys[num]);
+}
+
static inline bool cpus_have_cap(unsigned int num)
{
if (num >= ARM64_NCAPS)
return false;
- if (__builtin_constant_p(num))
- return static_branch_unlikely(&cpu_hwcap_keys[num]);
- else
- return test_bit(num, cpu_hwcaps);
+ return test_bit(num, cpu_hwcaps);
}
static inline void cpus_set_cap(unsigned int num)
@@ -200,7 +205,7 @@ static inline bool cpu_supports_mixed_endian_el0(void)
static inline bool system_supports_32bit_el0(void)
{
- return cpus_have_cap(ARM64_HAS_32BIT_EL0);
+ return cpus_have_const_cap(ARM64_HAS_32BIT_EL0);
}
static inline bool system_supports_mixed_endian_el0(void)
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index c02504e..fc2bd19 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -1102,5 +1102,5 @@ void __init setup_cpu_features(void)
static bool __maybe_unused
cpufeature_pan_not_uao(const struct arm64_cpu_capabilities *entry, int
__unused)
{
- return (cpus_have_cap(ARM64_HAS_PAN) && !cpus_have_cap(ARM64_HAS_UAO));
+ return (cpus_have_const_cap(ARM64_HAS_PAN) &&
!cpus_have_const_cap(ARM64_HAS_UAO));
}
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 01753cd..18354f3 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -282,7 +282,7 @@ int copy_thread(unsigned long clone_flags, unsigned long
stack_start,
memset(childregs, 0, sizeof(struct pt_regs));
childregs->pstate = PSR_MODE_EL1h;
if (IS_ENABLED(CONFIG_ARM64_UAO) &&
- cpus_have_cap(ARM64_HAS_UAO))
+ cpus_have_const_cap(ARM64_HAS_UAO))
childregs->pstate |= PSR_UAO_BIT;
p->thread.cpu_context.x19 = stack_start;
p->thread.cpu_context.x20 = stk_sz;
diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 19d642e..26e1d7f 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -120,11 +120,10 @@ static void gic_redist_wait_for_rwp(void)
}
#ifdef CONFIG_ARM64
-static DEFINE_STATIC_KEY_FALSE(is_cavium_thunderx);
static u64 __maybe_unused gic_read_iar(void)
{
- if (static_branch_unlikely(&is_cavium_thunderx))
+ if (cpus_have_const_cap(ARM64_WORKAROUND_CAVIUM_23154))
return gic_read_iar_cavium_thunderx();
else
return gic_read_iar_common();
@@ -905,14 +904,6 @@ static const struct irq_domain_ops partition_domain_ops = {
.select = gic_irq_domain_select,
};
-static void gicv3_enable_quirks(void)
-{
-#ifdef CONFIG_ARM64
- if (cpus_have_cap(ARM64_WORKAROUND_CAVIUM_23154))
- static_branch_enable(&is_cavium_thunderx);
-#endif
-}
-
static int __init gic_init_bases(void __iomem *dist_base,
struct redist_region *rdist_regs,
u32 nr_redist_regions,
@@ -935,8 +926,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
gic_data.nr_redist_regions = nr_redist_regions;
gic_data.redist_stride = redist_stride;
- gicv3_enable_quirks();
-
/*
* Find out how many interrupts are supported.
* The GIC only supports up to 1020 interrupt sources (SGI+PPI+SPI)
--
2.7.4
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