summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
Diffstat
-rw-r--r--arch/arm64/Kconfig21
-rw-r--r--arch/arm64/include/asm/alternative.h72
-rw-r--r--arch/arm64/include/asm/cpufeature.h3
-rw-r--r--arch/arm64/include/asm/processor.h1
-rw-r--r--arch/arm64/include/asm/sysreg.h3
-rw-r--r--arch/arm64/include/asm/thread_info.h6
-rw-r--r--arch/arm64/include/asm/uaccess.h44
-rw-r--r--arch/arm64/include/uapi/asm/ptrace.h1
-rw-r--r--arch/arm64/kernel/cpufeature.c11
-rw-r--r--arch/arm64/kernel/process.c19
-rw-r--r--arch/arm64/lib/clear_user.S8
-rw-r--r--arch/arm64/lib/copy_from_user.S8
-rw-r--r--arch/arm64/lib/copy_in_user.S16
-rw-r--r--arch/arm64/lib/copy_to_user.S8
-rw-r--r--arch/arm64/mm/fault.c31
15 files changed, 213 insertions, 39 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index fa51ff0470c1..3d9cab156740 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -756,6 +756,27 @@ config ARM64_LSE_ATOMICS
endmenu
+config ARM64_UAO
+ bool "Enable support for User Access Override (UAO)"
+ default y
+ help
+ User Access Override (UAO; part of the ARMv8.2 Extensions)
+ causes the 'unprivileged' variant of the load/store instructions to
+ be overriden to be privileged.
+
+ This option changes get_user() and friends to use the 'unprivileged'
+ variant of the load/store instructions. This ensures that user-space
+ really did have access to the supplied memory. When addr_limit is
+ set to kernel memory the UAO bit will be set, allowing privileged
+ access to kernel memory.
+
+ Choosing this option will cause copy_to_user() et al to use user-space
+ memory permissions.
+
+ The feature is detected at runtime, the kernel will use the
+ regular load/store instructions if the cpu does not implement the
+ feature.
+
endmenu
menu "Boot options"
diff --git a/arch/arm64/include/asm/alternative.h b/arch/arm64/include/asm/alternative.h
index e4962f04201e..a9fc24ec1aa9 100644
--- a/arch/arm64/include/asm/alternative.h
+++ b/arch/arm64/include/asm/alternative.h
@@ -1,6 +1,8 @@
#ifndef __ASM_ALTERNATIVE_H
#define __ASM_ALTERNATIVE_H
+#include <asm/cpufeature.h>
+
#ifndef __ASSEMBLY__
#include <linux/init.h>
@@ -63,6 +65,8 @@ void apply_alternatives(void *start, size_t length);
#else
+#include <asm/assembler.h>
+
.macro altinstruction_entry orig_offset alt_offset feature orig_len alt_len
.word \orig_offset - .
.word \alt_offset - .
@@ -136,6 +140,74 @@ void apply_alternatives(void *start, size_t length);
alternative_insn insn1, insn2, cap, IS_ENABLED(cfg)
+/*
+ * Generate the assembly for UAO alternatives with exception table entries.
+ * This is complicated as there is no post-increment or pair versions of the
+ * unprivileged instructions, and USER() only works for single instructions.
+ */
+#ifdef CONFIG_ARM64_UAO
+ .macro uao_ldp l, reg1, reg2, addr, post_inc
+ alternative_if_not ARM64_HAS_UAO
+8888: ldp \reg1, \reg2, [\addr], \post_inc;
+8889: nop;
+ nop;
+ alternative_else
+ ldtr \reg1, [\addr];
+ ldtr \reg2, [\addr, #8];
+ add \addr, \addr, \post_inc;
+ alternative_endif
+
+ .section __ex_table,"a";
+ .align 3;
+ .quad 8888b,\l;
+ .quad 8889b,\l;
+ .previous;
+ .endm
+
+ .macro uao_stp l, reg1, reg2, addr, post_inc
+ alternative_if_not ARM64_HAS_UAO
+8888: stp \reg1, \reg2, [\addr], \post_inc;
+8889: nop;
+ nop;
+ alternative_else
+ sttr \reg1, [\addr];
+ sttr \reg2, [\addr, #8];
+ add \addr, \addr, \post_inc;
+ alternative_endif
+
+ .section __ex_table,"a";
+ .align 3;
+ .quad 8888b,\l;
+ .quad 8889b,\l;
+ .previous
+ .endm
+
+ .macro uao_user_alternative l, inst, alt_inst, reg, addr, post_inc
+ alternative_if_not ARM64_HAS_UAO
+8888: \inst \reg, [\addr], \post_inc;
+ nop;
+ alternative_else
+ \alt_inst \reg, [\addr];
+ add \addr, \addr, \post_inc;
+ alternative_endif
+
+ .section __ex_table,"a";
+ .align 3;
+ .quad 8888b,\l;
+ .previous
+ .endm
+#else
+ .macro uao_ldp l, reg1, reg2, addr, post_inc
+ USER(\l, ldp \reg1, \reg2, [\addr], \post_inc)
+ .endm
+ .macro uao_stp l, reg1, reg2, addr, post_inc
+ USER(\l, stp \reg1, \reg2, [\addr], \post_inc)
+ .endm
+ .macro uao_user_alternative l, inst, alt_inst, reg, addr, post_inc
+ USER(\l, \inst \reg, [\addr], \post_inc)
+ .endm
+#endif
+
#endif /* __ASSEMBLY__ */
/*
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 8131abfabb0a..a5df7cde616b 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -31,8 +31,9 @@
#define ARM64_WORKAROUND_CAVIUM_23154 6
#define ARM64_WORKAROUND_834220 7
#define ARM64_HAS_NO_HW_PREFETCH 8
+#define ARM64_HAS_UAO 9
-#define ARM64_NCAPS 9
+#define ARM64_NCAPS 10
#ifndef __ASSEMBLY__
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h
index 5bb1d763d17a..cef1cf398356 100644
--- a/arch/arm64/include/asm/processor.h
+++ b/arch/arm64/include/asm/processor.h
@@ -191,5 +191,6 @@ static inline void spin_lock_prefetch(const void *ptr)
#endif
void cpu_enable_pan(void *__unused);
+void cpu_enable_uao(void *__unused);
#endif /* __ASM_PROCESSOR_H */
diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h
index e9c68e636576..1a78d6e2a78b 100644
--- a/arch/arm64/include/asm/sysreg.h
+++ b/arch/arm64/include/asm/sysreg.h
@@ -79,9 +79,12 @@
#define SYS_DCZID_EL0 sys_reg(3, 3, 0, 0, 7)
#define REG_PSTATE_PAN_IMM sys_reg(0, 0, 4, 0, 4)
+#define REG_PSTATE_UAO_IMM sys_reg(0, 0, 4, 0, 3)
#define SET_PSTATE_PAN(x) __inst_arm(0xd5000000 | REG_PSTATE_PAN_IMM |\
(!!x)<<8 | 0x1f)
+#define SET_PSTATE_UAO(x) __inst_arm(0xd5000000 | REG_PSTATE_UAO_IMM |\
+ (!!x)<<8 | 0x1f)
/* SCTLR_EL1 */
#define SCTLR_EL1_CP15BEN (0x1 << 5)
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index abd64bd1f6d9..eba8db6838af 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -85,6 +85,12 @@ static inline struct thread_info *current_thread_info(void)
return (struct thread_info *)sp_el0;
}
+/* Access struct thread_info of another thread */
+static inline struct thread_info *get_thread_info(unsigned long thread_stack)
+{
+ return (struct thread_info *)(thread_stack & ~(THREAD_SIZE - 1));
+}
+
#define thread_saved_pc(tsk) \
((unsigned long)(tsk->thread.cpu_context.pc))
#define thread_saved_sp(tsk) \
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index b2ede967fe7d..f973bdce8410 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -64,6 +64,16 @@ extern int fixup_exception(struct pt_regs *regs);
static inline void set_fs(mm_segment_t fs)
{
current_thread_info()->addr_limit = fs;
+
+ /*
+ * Enable/disable UAO so that copy_to_user() etc can access
+ * kernel memory with the unprivileged instructions.
+ */
+ if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS)
+ asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
+ else
+ asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO,
+ CONFIG_ARM64_UAO));
}
#define segment_eq(a, b) ((a) == (b))
@@ -113,9 +123,10 @@ static inline void set_fs(mm_segment_t fs)
* The "__xxx_error" versions set the third argument to -EFAULT if an error
* occurs, and leave it unchanged on success.
*/
-#define __get_user_asm(instr, reg, x, addr, err) \
+#define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \
asm volatile( \
- "1: " instr " " reg "1, [%2]\n" \
+ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \
+ alt_instr " " reg "1, [%2]\n", feature) \
"2:\n" \
" .section .fixup, \"ax\"\n" \
" .align 2\n" \
@@ -138,16 +149,20 @@ do { \
CONFIG_ARM64_PAN)); \
switch (sizeof(*(ptr))) { \
case 1: \
- __get_user_asm("ldrb", "%w", __gu_val, (ptr), (err)); \
+ __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 2: \
- __get_user_asm("ldrh", "%w", __gu_val, (ptr), (err)); \
+ __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 4: \
- __get_user_asm("ldr", "%w", __gu_val, (ptr), (err)); \
+ __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 8: \
- __get_user_asm("ldr", "%", __gu_val, (ptr), (err)); \
+ __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
default: \
BUILD_BUG(); \
@@ -181,9 +196,10 @@ do { \
((x) = 0, -EFAULT); \
})
-#define __put_user_asm(instr, reg, x, addr, err) \
+#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \
asm volatile( \
- "1: " instr " " reg "1, [%2]\n" \
+ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \
+ alt_instr " " reg "1, [%2]\n", feature) \
"2:\n" \
" .section .fixup,\"ax\"\n" \
" .align 2\n" \
@@ -205,16 +221,20 @@ do { \
CONFIG_ARM64_PAN)); \
switch (sizeof(*(ptr))) { \
case 1: \
- __put_user_asm("strb", "%w", __pu_val, (ptr), (err)); \
+ __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 2: \
- __put_user_asm("strh", "%w", __pu_val, (ptr), (err)); \
+ __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 4: \
- __put_user_asm("str", "%w", __pu_val, (ptr), (err)); \
+ __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
case 8: \
- __put_user_asm("str", "%", __pu_val, (ptr), (err)); \
+ __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
break; \
default: \
BUILD_BUG(); \
diff --git a/arch/arm64/include/uapi/asm/ptrace.h b/arch/arm64/include/uapi/asm/ptrace.h
index 208db3df135a..b5c3933ed441 100644
--- a/arch/arm64/include/uapi/asm/ptrace.h
+++ b/arch/arm64/include/uapi/asm/ptrace.h
@@ -45,6 +45,7 @@
#define PSR_A_BIT 0x00000100
#define PSR_D_BIT 0x00000200
#define PSR_PAN_BIT 0x00400000
+#define PSR_UAO_BIT 0x00800000
#define PSR_Q_BIT 0x08000000
#define PSR_V_BIT 0x10000000
#define PSR_C_BIT 0x20000000
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 42918c797e8e..ae22edf9d3c9 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -677,6 +677,17 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
.capability = ARM64_HAS_NO_HW_PREFETCH,
.matches = has_no_hw_prefetch,
},
+#ifdef CONFIG_ARM64_UAO
+ {
+ .desc = "User Access Override",
+ .capability = ARM64_HAS_UAO,
+ .matches = has_cpuid_feature,
+ .sys_reg = SYS_ID_AA64MMFR2_EL1,
+ .field_pos = ID_AA64MMFR2_UAO_SHIFT,
+ .min_field_value = 1,
+ .enable = cpu_enable_uao,
+ },
+#endif /* CONFIG_ARM64_UAO */
{},
};
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 88d742ba19d5..c1ca4ea065d4 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -46,6 +46,7 @@
#include <linux/notifier.h>
#include <trace/events/power.h>
+#include <asm/alternative.h>
#include <asm/compat.h>
#include <asm/cacheflush.h>
#include <asm/fpsimd.h>
@@ -280,6 +281,9 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
} else {
memset(childregs, 0, sizeof(struct pt_regs));
childregs->pstate = PSR_MODE_EL1h;
+ if (IS_ENABLED(CONFIG_ARM64_UAO) &&
+ cpus_have_cap(ARM64_HAS_UAO))
+ childregs->pstate |= PSR_UAO_BIT;
p->thread.cpu_context.x19 = stack_start;
p->thread.cpu_context.x20 = stk_sz;
}
@@ -308,6 +312,20 @@ static void tls_thread_switch(struct task_struct *next)
: : "r" (tpidr), "r" (tpidrro));
}
+/* Restore the UAO state depending on next's addr_limit */
+static void uao_thread_switch(struct task_struct *next)
+{
+ unsigned long next_sp = next->thread.cpu_context.sp;
+
+ if (IS_ENABLED(CONFIG_ARM64_UAO) &&
+ get_thread_info(next_sp)->addr_limit == KERNEL_DS)
+ asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO,
+ CONFIG_ARM64_UAO));
+ else
+ asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO,
+ CONFIG_ARM64_UAO));
+}
+
/*
* Thread switching.
*/
@@ -320,6 +338,7 @@ struct task_struct *__switch_to(struct task_struct *prev,
tls_thread_switch(next);
hw_breakpoint_thread_switch(next);
contextidr_thread_switch(next);
+ uao_thread_switch(next);
/*
* Complete any pending TLB or cache maintenance on this CPU in case
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index a9723c71c52b..3f950b677c07 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -39,20 +39,20 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
subs x1, x1, #8
b.mi 2f
1:
-USER(9f, str xzr, [x0], #8 )
+uao_user_alternative 9f, str, sttr, xzr, x0, 8
subs x1, x1, #8
b.pl 1b
2: adds x1, x1, #4
b.mi 3f
-USER(9f, str wzr, [x0], #4 )
+uao_user_alternative 9f, str, sttr, wzr, x0, 4
sub x1, x1, #4
3: adds x1, x1, #2
b.mi 4f
-USER(9f, strh wzr, [x0], #2 )
+uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
sub x1, x1, #2
4: adds x1, x1, #1
b.mi 5f
-USER(9f, strb wzr, [x0] )
+uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
5: mov x0, #0
ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN)
diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S
index 4699cd74f87e..1d982d64f1a7 100644
--- a/arch/arm64/lib/copy_from_user.S
+++ b/arch/arm64/lib/copy_from_user.S
@@ -34,7 +34,7 @@
*/
.macro ldrb1 ptr, regB, val
- USER(9998f, ldrb \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldrb, ldtrb, \ptr, \regB, \val
.endm
.macro strb1 ptr, regB, val
@@ -42,7 +42,7 @@
.endm
.macro ldrh1 ptr, regB, val
- USER(9998f, ldrh \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val
.endm
.macro strh1 ptr, regB, val
@@ -50,7 +50,7 @@
.endm
.macro ldr1 ptr, regB, val
- USER(9998f, ldr \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val
.endm
.macro str1 ptr, regB, val
@@ -58,7 +58,7 @@
.endm
.macro ldp1 ptr, regB, regC, val
- USER(9998f, ldp \ptr, \regB, [\regC], \val)
+ uao_ldp 9998f, \ptr, \regB, \regC, \val
.endm
.macro stp1 ptr, regB, regC, val
diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S
index 81c8fc93c100..feaad1520dc1 100644
--- a/arch/arm64/lib/copy_in_user.S
+++ b/arch/arm64/lib/copy_in_user.S
@@ -35,35 +35,35 @@
* x0 - bytes not copied
*/
.macro ldrb1 ptr, regB, val
- USER(9998f, ldrb \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldrb, ldtrb, \ptr, \regB, \val
.endm
.macro strb1 ptr, regB, val
- USER(9998f, strb \ptr, [\regB], \val)
+ uao_user_alternative 9998f, strb, sttrb, \ptr, \regB, \val
.endm
.macro ldrh1 ptr, regB, val
- USER(9998f, ldrh \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val
.endm
.macro strh1 ptr, regB, val
- USER(9998f, strh \ptr, [\regB], \val)
+ uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val
.endm
.macro ldr1 ptr, regB, val
- USER(9998f, ldr \ptr, [\regB], \val)
+ uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val
.endm
.macro str1 ptr, regB, val
- USER(9998f, str \ptr, [\regB], \val)
+ uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val
.endm
.macro ldp1 ptr, regB, regC, val
- USER(9998f, ldp \ptr, \regB, [\regC], \val)
+ uao_ldp 9998f, \ptr, \regB, \regC, \val
.endm
.macro stp1 ptr, regB, regC, val
- USER(9998f, stp \ptr, \regB, [\regC], \val)
+ uao_stp 9998f, \ptr, \regB, \regC, \val
.endm
end .req x5
diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S
index 7512bbbc07ac..2dae2cd2c481 100644
--- a/arch/arm64/lib/copy_to_user.S
+++ b/arch/arm64/lib/copy_to_user.S
@@ -37,7 +37,7 @@
.endm
.macro strb1 ptr, regB, val
- USER(9998f, strb \ptr, [\regB], \val)
+ uao_user_alternative 9998f, strb, sttrb, \ptr, \regB, \val
.endm
.macro ldrh1 ptr, regB, val
@@ -45,7 +45,7 @@
.endm
.macro strh1 ptr, regB, val
- USER(9998f, strh \ptr, [\regB], \val)
+ uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val
.endm
.macro ldr1 ptr, regB, val
@@ -53,7 +53,7 @@
.endm
.macro str1 ptr, regB, val
- USER(9998f, str \ptr, [\regB], \val)
+ uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val
.endm
.macro ldp1 ptr, regB, regC, val
@@ -61,7 +61,7 @@
.endm
.macro stp1 ptr, regB, regC, val
- USER(9998f, stp \ptr, \regB, [\regC], \val)
+ uao_stp 9998f, \ptr, \regB, \regC, \val
.endm
end .req x5
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 92ddac1e8ca2..820d47353cf0 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -192,6 +192,14 @@ out:
return fault;
}
+static inline int permission_fault(unsigned int esr)
+{
+ unsigned int ec = (esr & ESR_ELx_EC_MASK) >> ESR_ELx_EC_SHIFT;
+ unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE;
+
+ return (ec == ESR_ELx_EC_DABT_CUR && fsc_type == ESR_ELx_FSC_PERM);
+}
+
static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
struct pt_regs *regs)
{
@@ -225,12 +233,10 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr,
mm_flags |= FAULT_FLAG_WRITE;
}
- /*
- * PAN bit set implies the fault happened in kernel space, but not
- * in the arch's user access functions.
- */
- if (IS_ENABLED(CONFIG_ARM64_PAN) && (regs->pstate & PSR_PAN_BIT))
- goto no_context;
+ if (permission_fault(esr) && (addr < USER_DS)) {
+ if (!search_exception_tables(regs->pc))
+ panic("Accessing user space memory outside uaccess.h routines");
+ }
/*
* As per x86, we may deadlock here. However, since the kernel only
@@ -561,3 +567,16 @@ void cpu_enable_pan(void *__unused)
config_sctlr_el1(SCTLR_EL1_SPAN, 0);
}
#endif /* CONFIG_ARM64_PAN */
+
+#ifdef CONFIG_ARM64_UAO
+/*
+ * Kernel threads have fs=KERNEL_DS by default, and don't need to call
+ * set_fs(), devtmpfs in particular relies on this behaviour.
+ * We need to enable the feature at runtime (instead of adding it to
+ * PSR_MODE_EL1h) as the feature may not be implemented by the cpu.
+ */
+void cpu_enable_uao(void *__unused)
+{
+ asm(SET_PSTATE_UAO(1));
+}
+#endif /* CONFIG_ARM64_UAO */
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-22 09:51:02 +0300