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-rw-r--r--arch/arm/kernel/setup.c29
-rw-r--r--arch/arm/kernel/swp_emulate.c4
-rw-r--r--arch/arm/mm/Kconfig2
3 files changed, 27 insertions, 8 deletions
diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 8a16ee5d8a95..84db893dedc2 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -393,19 +393,34 @@ static void __init cpuid_init_hwcaps(void)
elf_hwcap |= HWCAP_LPAE;
}
-static void __init feat_v6_fixup(void)
+static void __init elf_hwcap_fixup(void)
{
- int id = read_cpuid_id();
-
- if ((id & 0xff0f0000) != 0x41070000)
- return;
+ unsigned id = read_cpuid_id();
+ unsigned sync_prim;
/*
* HWCAP_TLS is available only on 1136 r1p0 and later,
* see also kuser_get_tls_init.
*/
- if ((((id >> 4) & 0xfff) == 0xb36) && (((id >> 20) & 3) == 0))
+ if (read_cpuid_part() == ARM_CPU_PART_ARM1136 &&
+ ((id >> 20) & 3) == 0) {
elf_hwcap &= ~HWCAP_TLS;
+ return;
+ }
+
+ /* Verify if CPUID scheme is implemented */
+ if ((id & 0x000f0000) != 0x000f0000)
+ return;
+
+ /*
+ * If the CPU supports LDREX/STREX and LDREXB/STREXB,
+ * avoid advertising SWP; it may not be atomic with
+ * multiprocessing cores.
+ */
+ sync_prim = ((read_cpuid_ext(CPUID_EXT_ISAR3) >> 8) & 0xf0) |
+ ((read_cpuid_ext(CPUID_EXT_ISAR4) >> 20) & 0x0f);
+ if (sync_prim >= 0x13)
+ elf_hwcap &= ~HWCAP_SWP;
}
/*
@@ -609,7 +624,7 @@ static void __init setup_processor(void)
#endif
erratum_a15_798181_init();
- feat_v6_fixup();
+ elf_hwcap_fixup();
cacheid_init();
cpu_init();
diff --git a/arch/arm/kernel/swp_emulate.c b/arch/arm/kernel/swp_emulate.c
index b1b89882b113..67ca8578c6d8 100644
--- a/arch/arm/kernel/swp_emulate.c
+++ b/arch/arm/kernel/swp_emulate.c
@@ -27,6 +27,7 @@
#include <linux/perf_event.h>
#include <asm/opcodes.h>
+#include <asm/system_info.h>
#include <asm/traps.h>
#include <asm/uaccess.h>
@@ -266,6 +267,9 @@ static struct undef_hook swp_hook = {
*/
static int __init swp_emulation_init(void)
{
+ if (cpu_architecture() < CPU_ARCH_ARMv7)
+ return 0;
+
#ifdef CONFIG_PROC_FS
if (!proc_create("cpu/swp_emulation", S_IRUGO, NULL, &proc_status_fops))
return -ENOMEM;
diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig
index df46620206af..577039a3f6e5 100644
--- a/arch/arm/mm/Kconfig
+++ b/arch/arm/mm/Kconfig
@@ -669,7 +669,7 @@ config ARM_VIRT_EXT
details.
config SWP_EMULATE
- bool "Emulate SWP/SWPB instructions"
+ bool "Emulate SWP/SWPB instructions" if !SMP
depends on CPU_V7
default y if SMP
select HAVE_PROC_CPU if PROC_FS