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-rw-r--r--arch/arm64/include/asm/uaccess.h175
1 files changed, 165 insertions, 10 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
index 55d0adbf6509..d26750ca6e06 100644
--- a/arch/arm64/include/asm/uaccess.h
+++ b/arch/arm64/include/asm/uaccess.h
@@ -18,6 +18,12 @@
#ifndef __ASM_UACCESS_H
#define __ASM_UACCESS_H
+#include <asm/alternative.h>
+#include <asm/kernel-pgtable.h>
+#include <asm/sysreg.h>
+
+#ifndef __ASSEMBLY__
+
/*
* User space memory access functions
*/
@@ -26,10 +32,8 @@
#include <linux/string.h>
#include <linux/thread_info.h>
-#include <asm/alternative.h>
#include <asm/cpufeature.h>
#include <asm/ptrace.h>
-#include <asm/sysreg.h>
#include <asm/errno.h>
#include <asm/memory.h>
#include <asm/compiler.h>
@@ -120,6 +124,99 @@ static inline void set_fs(mm_segment_t fs)
" .popsection\n"
/*
+ * User access enabling/disabling.
+ */
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+static inline void __uaccess_ttbr0_disable(void)
+{
+ unsigned long ttbr;
+
+ /* reserved_ttbr0 placed at the end of swapper_pg_dir */
+ ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE;
+ write_sysreg(ttbr, ttbr0_el1);
+ isb();
+}
+
+static inline void __uaccess_ttbr0_enable(void)
+{
+ unsigned long flags;
+
+ /*
+ * Disable interrupts to avoid preemption between reading the 'ttbr0'
+ * variable and the MSR. A context switch could trigger an ASID
+ * roll-over and an update of 'ttbr0'.
+ */
+ local_irq_save(flags);
+ write_sysreg(current_thread_info()->ttbr0, ttbr0_el1);
+ isb();
+ local_irq_restore(flags);
+}
+
+static inline bool uaccess_ttbr0_disable(void)
+{
+ if (!system_uses_ttbr0_pan())
+ return false;
+ __uaccess_ttbr0_disable();
+ return true;
+}
+
+static inline bool uaccess_ttbr0_enable(void)
+{
+ if (!system_uses_ttbr0_pan())
+ return false;
+ __uaccess_ttbr0_enable();
+ return true;
+}
+#else
+static inline bool uaccess_ttbr0_disable(void)
+{
+ return false;
+}
+
+static inline bool uaccess_ttbr0_enable(void)
+{
+ return false;
+}
+#endif
+
+#define __uaccess_disable(alt) \
+do { \
+ if (!uaccess_ttbr0_disable()) \
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \
+ CONFIG_ARM64_PAN)); \
+} while (0)
+
+#define __uaccess_enable(alt) \
+do { \
+ if (!uaccess_ttbr0_enable()) \
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \
+ CONFIG_ARM64_PAN)); \
+} while (0)
+
+static inline void uaccess_disable(void)
+{
+ __uaccess_disable(ARM64_HAS_PAN);
+}
+
+static inline void uaccess_enable(void)
+{
+ __uaccess_enable(ARM64_HAS_PAN);
+}
+
+/*
+ * These functions are no-ops when UAO is present.
+ */
+static inline void uaccess_disable_not_uao(void)
+{
+ __uaccess_disable(ARM64_ALT_PAN_NOT_UAO);
+}
+
+static inline void uaccess_enable_not_uao(void)
+{
+ __uaccess_enable(ARM64_ALT_PAN_NOT_UAO);
+}
+
+/*
* The "__xxx" versions of the user access functions do not verify the address
* space - it must have been done previously with a separate "access_ok()"
* call.
@@ -146,8 +243,7 @@ static inline void set_fs(mm_segment_t fs)
do { \
unsigned long __gu_val; \
__chk_user_ptr(ptr); \
- asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
- CONFIG_ARM64_PAN)); \
+ uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
@@ -168,9 +264,8 @@ do { \
default: \
BUILD_BUG(); \
} \
+ uaccess_disable_not_uao(); \
(x) = (__force __typeof__(*(ptr)))__gu_val; \
- asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
- CONFIG_ARM64_PAN)); \
} while (0)
#define __get_user(x, ptr) \
@@ -215,8 +310,7 @@ do { \
do { \
__typeof__(*(ptr)) __pu_val = (x); \
__chk_user_ptr(ptr); \
- asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\
- CONFIG_ARM64_PAN)); \
+ uaccess_enable_not_uao(); \
switch (sizeof(*(ptr))) { \
case 1: \
__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
@@ -237,8 +331,7 @@ do { \
default: \
BUILD_BUG(); \
} \
- asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\
- CONFIG_ARM64_PAN)); \
+ uaccess_disable_not_uao(); \
} while (0)
#define __put_user(x, ptr) \
@@ -331,4 +424,66 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count);
extern __must_check long strlen_user(const char __user *str);
extern __must_check long strnlen_user(const char __user *str, long n);
+#else /* __ASSEMBLY__ */
+
+#include <asm/assembler.h>
+
+/*
+ * User access enabling/disabling macros.
+ */
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+ .macro __uaccess_ttbr0_disable, tmp1
+ mrs \tmp1, ttbr1_el1 // swapper_pg_dir
+ add \tmp1, \tmp1, #SWAPPER_DIR_SIZE // reserved_ttbr0 at the end of swapper_pg_dir
+ msr ttbr0_el1, \tmp1 // set reserved TTBR0_EL1
+ isb
+ .endm
+
+ .macro __uaccess_ttbr0_enable, tmp1
+ get_thread_info \tmp1
+ ldr \tmp1, [\tmp1, #TSK_TI_TTBR0] // load saved TTBR0_EL1
+ msr ttbr0_el1, \tmp1 // set the non-PAN TTBR0_EL1
+ isb
+ .endm
+
+ .macro uaccess_ttbr0_disable, tmp1
+alternative_if_not ARM64_HAS_PAN
+ __uaccess_ttbr0_disable \tmp1
+alternative_else_nop_endif
+ .endm
+
+ .macro uaccess_ttbr0_enable, tmp1, tmp2
+alternative_if_not ARM64_HAS_PAN
+ save_and_disable_irq \tmp2 // avoid preemption
+ __uaccess_ttbr0_enable \tmp1
+ restore_irq \tmp2
+alternative_else_nop_endif
+ .endm
+#else
+ .macro uaccess_ttbr0_disable, tmp1
+ .endm
+
+ .macro uaccess_ttbr0_enable, tmp1, tmp2
+ .endm
+#endif
+
+/*
+ * These macros are no-ops when UAO is present.
+ */
+ .macro uaccess_disable_not_uao, tmp1
+ uaccess_ttbr0_disable \tmp1
+alternative_if ARM64_ALT_PAN_NOT_UAO
+ SET_PSTATE_PAN(1)
+alternative_else_nop_endif
+ .endm
+
+ .macro uaccess_enable_not_uao, tmp1, tmp2
+ uaccess_ttbr0_enable \tmp1, \tmp2
+alternative_if ARM64_ALT_PAN_NOT_UAO
+ SET_PSTATE_PAN(0)
+alternative_else_nop_endif
+ .endm
+
+#endif /* __ASSEMBLY__ */
+
#endif /* __ASM_UACCESS_H */