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authorSuzuki K Poulose <suzuki.poulose@arm.com>2016-11-08 16:56:20 +0300
committerCatalin Marinas <catalin.marinas@arm.com>2016-11-16 20:50:51 +0300
commita4023f682739439b434165b54af7cb3676a4766e (patch)
treeef2638d37291c56d972f20b69c59a6dee9292c18 /arch/arm64
parentc02433dd6de32f042cf3ffe476746b1115b8c096 (diff)
downloadlinux-a4023f682739439b434165b54af7cb3676a4766e.tar.xz
arm64: Add hypervisor safe helper for checking constant capabilities
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 <rritcher@cavium.com> Cc: Tirumalesh Chalamarla <tchalamarla@cavium.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reviewed-by: Will Deacon <will.deacon@arm.com> Reviewed-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/include/asm/cpufeature.h19
-rw-r--r--arch/arm64/kernel/cpufeature.c2
-rw-r--r--arch/arm64/kernel/process.c2
3 files changed, 14 insertions, 9 deletions
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index a27c3245ba21..8b63adb148e7 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/hwcap.h>
#include <asm/sysreg.h>
@@ -45,6 +43,8 @@
#ifndef __ASSEMBLY__
+#include <linux/bug.h>
+#include <linux/jump_label.h>
#include <linux/kernel.h>
/* CPU feature register tracking */
@@ -122,14 +122,19 @@ 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)
@@ -218,7 +223,7 @@ 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 c02504ea304b..fc2bd1926607 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 a98b743631c5..a3a2816ba73a 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -283,7 +283,7 @@ 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;