From: Andre Przywara <andre.przywara@xxxxxxx>
For taking note if at least one CPU in the system needs a bug
workaround or would benefit from a code optimization, we create a new
bitmap to hold (artificial) feature bits.
Since elf_hwcap is part of the userland ABI, we keep it alone and
introduce a new data structure for that (along with some accessors).
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.18.y
(cherry picked from commit 930da09f5e50dd22fb0a8600388da8677d62d671)
Signed-off-by: Kevin Hilman <khilman@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
---
arch/arm64/include/asm/cpufeature.h | 20 ++++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +++
2 files changed, 23 insertions(+)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index cd4ac05..20b2b3d6 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -21,9 +21,29 @@
#define MAX_CPU_FEATURES (8 * sizeof(elf_hwcap))
#define cpu_feature(x) ilog2(HWCAP_ ## x)
+#define NCAPS 0
+
+extern DECLARE_BITMAP(cpu_hwcaps, NCAPS);
+
static inline bool cpu_have_feature(unsigned int num)
{
return elf_hwcap & (1UL << num);
}
+static inline bool cpus_have_cap(unsigned int num)
+{
+ if (num >= NCAPS)
+ return false;
+ return test_bit(num, cpu_hwcaps);
+}
+
+static inline void cpus_set_cap(unsigned int num)
+{
+ if (num >= NCAPS)
+ pr_warn("Attempt to set an illegal CPU capability (%d >= %d)\n",
+ num, NCAPS);
+ else
+ __set_bit(num, cpu_hwcaps);
+}
+
#endif
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index 38eead1..d502a86 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -50,6 +50,7 @@
#include <asm/cputype.h>
#include <asm/elf.h>
#include <asm/cputable.h>
+#include <asm/cpufeature.h>
#include <asm/cpu_ops.h>
#include <asm/sections.h>
#include <asm/setup.h>
@@ -79,6 +80,8 @@ unsigned int compat_elf_hwcap __read_mostly = COMPAT_ELF_HWCAP_DEFAULT;
unsigned int compat_elf_hwcap2 __read_mostly;
#endif
+DECLARE_BITMAP(cpu_hwcaps, NCAPS);
+
static const char *cpu_name;
phys_addr_t __fdt_pointer __initdata;
--
2.1.0
--
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