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-rw-r--r--arch/s390/include/asm/alternative.h5
-rw-r--r--arch/s390/include/asm/nospec-branch.h9
-rw-r--r--arch/s390/include/asm/processor.h2
-rw-r--r--arch/s390/kernel/alternative.c4
-rw-r--r--arch/s390/kernel/early.c2
-rw-r--r--arch/s390/kernel/entry.S8
-rw-r--r--arch/s390/kernel/nospec-branch.c16
-rw-r--r--arch/s390/kernel/nospec-sysfs.c2
8 files changed, 33 insertions, 15 deletions
diff --git a/arch/s390/include/asm/alternative.h b/arch/s390/include/asm/alternative.h
index 32c208332e57..5f56a2f3aba6 100644
--- a/arch/s390/include/asm/alternative.h
+++ b/arch/s390/include/asm/alternative.h
@@ -33,6 +33,7 @@
#define ALT_TYPE_FACILITY_EARLY 0
#define ALT_TYPE_FACILITY 1
+#define ALT_TYPE_SPEC 2
#define ALT_DATA_SHIFT 0
#define ALT_TYPE_SHIFT 20
@@ -46,6 +47,10 @@
ALT_TYPE_FACILITY << ALT_TYPE_SHIFT | \
(facility) << ALT_DATA_SHIFT)
+#define ALT_SPEC(facility) (ALT_CTX_LATE << ALT_CTX_SHIFT | \
+ ALT_TYPE_SPEC << ALT_TYPE_SHIFT | \
+ (facility) << ALT_DATA_SHIFT)
+
#ifndef __ASSEMBLY__
#include <linux/types.h>
diff --git a/arch/s390/include/asm/nospec-branch.h b/arch/s390/include/asm/nospec-branch.h
index b9c1f3cae842..192835a3e24d 100644
--- a/arch/s390/include/asm/nospec-branch.h
+++ b/arch/s390/include/asm/nospec-branch.h
@@ -5,8 +5,17 @@
#ifndef __ASSEMBLY__
#include <linux/types.h>
+#include <asm/facility.h>
extern int nospec_disable;
+extern int nobp;
+
+static inline bool nobp_enabled(void)
+{
+ if (__is_defined(__DECOMPRESSOR))
+ return false;
+ return nobp && test_facility(82);
+}
void nospec_init_branches(void);
void nospec_auto_detect(void);
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index 8a52554f49f0..3063488014eb 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -419,7 +419,7 @@ static __always_inline bool regs_irqs_disabled(struct pt_regs *regs)
static __always_inline void bpon(void)
{
- asm volatile(ALTERNATIVE("nop", ".insn rrf,0xb2e80000,0,0,13,0", ALT_FACILITY(82)));
+ asm volatile(ALTERNATIVE("nop", ".insn rrf,0xb2e80000,0,0,13,0", ALT_SPEC(82)));
}
#endif /* __ASSEMBLY__ */
diff --git a/arch/s390/kernel/alternative.c b/arch/s390/kernel/alternative.c
index de89c9e8b1a3..05545669552f 100644
--- a/arch/s390/kernel/alternative.c
+++ b/arch/s390/kernel/alternative.c
@@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/uaccess.h>
+#include <asm/nospec-branch.h>
#include <asm/alternative.h>
#include <asm/facility.h>
@@ -26,6 +27,9 @@ void __apply_alternatives(struct alt_instr *start, struct alt_instr *end, unsign
replace = __test_facility(a->data, alt_stfle_fac_list);
break;
#endif
+ case ALT_TYPE_SPEC:
+ replace = nobp_enabled();
+ break;
default:
replace = false;
}
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 467ed4dba817..d142598e0532 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -193,8 +193,6 @@ static noinline __init void setup_lowcore_early(void)
static noinline __init void setup_facility_list(void)
{
memcpy(alt_stfle_fac_list, stfle_fac_list, sizeof(alt_stfle_fac_list));
- if (!IS_ENABLED(CONFIG_KERNEL_NOBP))
- __clear_facility(82, alt_stfle_fac_list);
}
static __init void detect_diag9c(void)
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 90027a57a524..8caf893d1b59 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -100,22 +100,22 @@ _LPP_OFFSET = __LC_LPP
.endm
.macro BPOFF
- ALTERNATIVE "nop", ".insn rrf,0xb2e80000,0,0,12,0", ALT_FACILITY(82)
+ ALTERNATIVE "nop", ".insn rrf,0xb2e80000,0,0,12,0", ALT_SPEC(82)
.endm
.macro BPON
- ALTERNATIVE "nop", ".insn rrf,0xb2e80000,0,0,13,0", ALT_FACILITY(82)
+ ALTERNATIVE "nop", ".insn rrf,0xb2e80000,0,0,13,0", ALT_SPEC(82)
.endm
.macro BPENTER tif_ptr,tif_mask
ALTERNATIVE "TSTMSK \tif_ptr,\tif_mask; jz .+8; .insn rrf,0xb2e80000,0,0,13,0", \
- "j .+12; nop; nop", ALT_FACILITY(82)
+ "j .+12; nop; nop", ALT_SPEC(82)
.endm
.macro BPEXIT tif_ptr,tif_mask
TSTMSK \tif_ptr,\tif_mask
ALTERNATIVE "jz .+8; .insn rrf,0xb2e80000,0,0,12,0", \
- "jnz .+8; .insn rrf,0xb2e80000,0,0,13,0", ALT_FACILITY(82)
+ "jnz .+8; .insn rrf,0xb2e80000,0,0,13,0", ALT_SPEC(82)
.endm
#if IS_ENABLED(CONFIG_KVM)
diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c
index 9b8c24ebb008..e11ec15960a1 100644
--- a/arch/s390/kernel/nospec-branch.c
+++ b/arch/s390/kernel/nospec-branch.c
@@ -4,6 +4,8 @@
#include <linux/cpu.h>
#include <asm/nospec-branch.h>
+int nobp = IS_ENABLED(CONFIG_KERNEL_NOBP);
+
static int __init nobp_setup_early(char *str)
{
bool enabled;
@@ -17,11 +19,11 @@ static int __init nobp_setup_early(char *str)
* The user explicitly requested nobp=1, enable it and
* disable the expoline support.
*/
- __set_facility(82, alt_stfle_fac_list);
+ nobp = 1;
if (IS_ENABLED(CONFIG_EXPOLINE))
nospec_disable = 1;
} else {
- __clear_facility(82, alt_stfle_fac_list);
+ nobp = 0;
}
return 0;
}
@@ -29,7 +31,7 @@ early_param("nobp", nobp_setup_early);
static int __init nospec_setup_early(char *str)
{
- __clear_facility(82, alt_stfle_fac_list);
+ nobp = 0;
return 0;
}
early_param("nospec", nospec_setup_early);
@@ -40,7 +42,7 @@ static int __init nospec_report(void)
pr_info("Spectre V2 mitigation: etokens\n");
if (nospec_uses_trampoline())
pr_info("Spectre V2 mitigation: execute trampolines\n");
- if (__test_facility(82, alt_stfle_fac_list))
+ if (nobp_enabled())
pr_info("Spectre V2 mitigation: limited branch prediction\n");
return 0;
}
@@ -66,14 +68,14 @@ void __init nospec_auto_detect(void)
*/
if (__is_defined(CC_USING_EXPOLINE))
nospec_disable = 1;
- __clear_facility(82, alt_stfle_fac_list);
+ nobp = 0;
} else if (__is_defined(CC_USING_EXPOLINE)) {
/*
* The kernel has been compiled with expolines.
* Keep expolines enabled and disable nobp.
*/
nospec_disable = 0;
- __clear_facility(82, alt_stfle_fac_list);
+ nobp = 0;
}
/*
* If the kernel has not been compiled with expolines the
@@ -86,7 +88,7 @@ static int __init spectre_v2_setup_early(char *str)
{
if (str && !strncmp(str, "on", 2)) {
nospec_disable = 0;
- __clear_facility(82, alt_stfle_fac_list);
+ nobp = 0;
}
if (str && !strncmp(str, "off", 3))
nospec_disable = 1;
diff --git a/arch/s390/kernel/nospec-sysfs.c b/arch/s390/kernel/nospec-sysfs.c
index 52d4353188ad..a95188818637 100644
--- a/arch/s390/kernel/nospec-sysfs.c
+++ b/arch/s390/kernel/nospec-sysfs.c
@@ -17,7 +17,7 @@ ssize_t cpu_show_spectre_v2(struct device *dev,
return sprintf(buf, "Mitigation: etokens\n");
if (nospec_uses_trampoline())
return sprintf(buf, "Mitigation: execute trampolines\n");
- if (__test_facility(82, alt_stfle_fac_list))
+ if (nobp_enabled())
return sprintf(buf, "Mitigation: limited branch prediction\n");
return sprintf(buf, "Vulnerable\n");
}
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