summaryrefslogtreecommitdiffstats
path: root/arch/arm64/include/asm/uaccess.h
diff options
context:
space:
mode:
Diffstat (limited to 'arch/arm64/include/asm/uaccess.h')
-rw-r--r--arch/arm64/include/asm/uaccess.h452
1 files changed, 452 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h
new file mode 100644
index 000000000..e66b0fca9
--- /dev/null
+++ b/arch/arm64/include/asm/uaccess.h
@@ -0,0 +1,452 @@
+/*
+ * Based on arch/arm/include/asm/uaccess.h
+ *
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ASM_UACCESS_H
+#define __ASM_UACCESS_H
+
+#include <asm/alternative.h>
+#include <asm/kernel-pgtable.h>
+#include <asm/sysreg.h>
+
+/*
+ * User space memory access functions
+ */
+#include <linux/bitops.h>
+#include <linux/kasan-checks.h>
+#include <linux/string.h>
+
+#include <asm/cpufeature.h>
+#include <asm/ptrace.h>
+#include <asm/memory.h>
+#include <asm/compiler.h>
+#include <asm/extable.h>
+
+#define get_ds() (KERNEL_DS)
+#define get_fs() (current_thread_info()->addr_limit)
+
+static inline void set_fs(mm_segment_t fs)
+{
+ current_thread_info()->addr_limit = fs;
+
+ /*
+ * Prevent a mispredicted conditional call to set_fs from forwarding
+ * the wrong address limit to access_ok under speculation.
+ */
+ dsb(nsh);
+ isb();
+
+ /* On user-mode return, check fs is correct */
+ set_thread_flag(TIF_FSCHECK);
+
+ /*
+ * 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))
+
+/*
+ * Test whether a block of memory is a valid user space address.
+ * Returns 1 if the range is valid, 0 otherwise.
+ *
+ * This is equivalent to the following test:
+ * (u65)addr + (u65)size <= (u65)current->addr_limit + 1
+ */
+static inline unsigned long __range_ok(const void __user *addr, unsigned long size)
+{
+ unsigned long ret, limit = current_thread_info()->addr_limit;
+
+ __chk_user_ptr(addr);
+ asm volatile(
+ // A + B <= C + 1 for all A,B,C, in four easy steps:
+ // 1: X = A + B; X' = X % 2^64
+ " adds %0, %3, %2\n"
+ // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4
+ " csel %1, xzr, %1, hi\n"
+ // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X'
+ // to compensate for the carry flag being set in step 4. For
+ // X > 2^64, X' merely has to remain nonzero, which it does.
+ " csinv %0, %0, xzr, cc\n"
+ // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1
+ // comes from the carry in being clear. Otherwise, we are
+ // testing X' - C == 0, subject to the previous adjustments.
+ " sbcs xzr, %0, %1\n"
+ " cset %0, ls\n"
+ : "=&r" (ret), "+r" (limit) : "Ir" (size), "0" (addr) : "cc");
+
+ return ret;
+}
+
+/*
+ * When dealing with data aborts, watchpoints, or instruction traps we may end
+ * up with a tagged userland pointer. Clear the tag to get a sane pointer to
+ * pass on to access_ok(), for instance.
+ */
+#define untagged_addr(addr) sign_extend64(addr, 55)
+
+#define access_ok(type, addr, size) __range_ok(addr, size)
+#define user_addr_max get_fs
+
+#define _ASM_EXTABLE(from, to) \
+ " .pushsection __ex_table, \"a\"\n" \
+ " .align 3\n" \
+ " .long (" #from " - .), (" #to " - .)\n" \
+ " .popsection\n"
+
+/*
+ * User access enabling/disabling.
+ */
+#ifdef CONFIG_ARM64_SW_TTBR0_PAN
+static inline void __uaccess_ttbr0_disable(void)
+{
+ unsigned long flags, ttbr;
+
+ local_irq_save(flags);
+ ttbr = read_sysreg(ttbr1_el1);
+ ttbr &= ~TTBR_ASID_MASK;
+ /* reserved_ttbr0 placed before swapper_pg_dir */
+ write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
+ isb();
+ /* Set reserved ASID */
+ write_sysreg(ttbr, ttbr1_el1);
+ isb();
+ local_irq_restore(flags);
+}
+
+static inline void __uaccess_ttbr0_enable(void)
+{
+ unsigned long flags, ttbr0, ttbr1;
+
+ /*
+ * 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);
+ ttbr0 = READ_ONCE(current_thread_info()->ttbr0);
+
+ /* Restore active ASID */
+ ttbr1 = read_sysreg(ttbr1_el1);
+ ttbr1 &= ~TTBR_ASID_MASK; /* safety measure */
+ ttbr1 |= ttbr0 & TTBR_ASID_MASK;
+ write_sysreg(ttbr1, ttbr1_el1);
+ isb();
+
+ /* Restore user page table */
+ write_sysreg(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
+
+static inline void __uaccess_disable_hw_pan(void)
+{
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN,
+ CONFIG_ARM64_PAN));
+}
+
+static inline void __uaccess_enable_hw_pan(void)
+{
+ asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN,
+ CONFIG_ARM64_PAN));
+}
+
+#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);
+}
+
+/*
+ * Sanitise a uaccess pointer such that it becomes NULL if above the
+ * current addr_limit.
+ */
+#define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr)
+static inline void __user *__uaccess_mask_ptr(const void __user *ptr)
+{
+ void __user *safe_ptr;
+
+ asm volatile(
+ " bics xzr, %1, %2\n"
+ " csel %0, %1, xzr, eq\n"
+ : "=&r" (safe_ptr)
+ : "r" (ptr), "r" (current_thread_info()->addr_limit)
+ : "cc");
+
+ csdb();
+ return safe_ptr;
+}
+
+/*
+ * 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.
+ *
+ * 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, alt_instr, reg, x, addr, err, feature) \
+ asm volatile( \
+ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \
+ alt_instr " " reg "1, [%2]\n", feature) \
+ "2:\n" \
+ " .section .fixup, \"ax\"\n" \
+ " .align 2\n" \
+ "3: mov %w0, %3\n" \
+ " mov %1, #0\n" \
+ " b 2b\n" \
+ " .previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (err), "=&r" (x) \
+ : "r" (addr), "i" (-EFAULT))
+
+#define __get_user_err(x, ptr, err) \
+do { \
+ unsigned long __gu_val; \
+ __chk_user_ptr(ptr); \
+ uaccess_enable_not_uao(); \
+ switch (sizeof(*(ptr))) { \
+ case 1: \
+ __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 2: \
+ __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 4: \
+ __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 8: \
+ __get_user_asm("ldr", "ldtr", "%x", __gu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
+ uaccess_disable_not_uao(); \
+ (x) = (__force __typeof__(*(ptr)))__gu_val; \
+} while (0)
+
+#define __get_user_check(x, ptr, err) \
+({ \
+ __typeof__(*(ptr)) __user *__p = (ptr); \
+ might_fault(); \
+ if (access_ok(VERIFY_READ, __p, sizeof(*__p))) { \
+ __p = uaccess_mask_ptr(__p); \
+ __get_user_err((x), __p, (err)); \
+ } else { \
+ (x) = 0; (err) = -EFAULT; \
+ } \
+})
+
+#define __get_user_error(x, ptr, err) \
+({ \
+ __get_user_check((x), (ptr), (err)); \
+ (void)0; \
+})
+
+#define __get_user(x, ptr) \
+({ \
+ int __gu_err = 0; \
+ __get_user_check((x), (ptr), __gu_err); \
+ __gu_err; \
+})
+
+#define get_user __get_user
+
+#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \
+ asm volatile( \
+ "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \
+ alt_instr " " reg "1, [%2]\n", feature) \
+ "2:\n" \
+ " .section .fixup,\"ax\"\n" \
+ " .align 2\n" \
+ "3: mov %w0, %3\n" \
+ " b 2b\n" \
+ " .previous\n" \
+ _ASM_EXTABLE(1b, 3b) \
+ : "+r" (err) \
+ : "r" (x), "r" (addr), "i" (-EFAULT))
+
+#define __put_user_err(x, ptr, err) \
+do { \
+ __typeof__(*(ptr)) __pu_val = (x); \
+ __chk_user_ptr(ptr); \
+ uaccess_enable_not_uao(); \
+ switch (sizeof(*(ptr))) { \
+ case 1: \
+ __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 2: \
+ __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 4: \
+ __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ case 8: \
+ __put_user_asm("str", "sttr", "%x", __pu_val, (ptr), \
+ (err), ARM64_HAS_UAO); \
+ break; \
+ default: \
+ BUILD_BUG(); \
+ } \
+ uaccess_disable_not_uao(); \
+} while (0)
+
+#define __put_user_check(x, ptr, err) \
+({ \
+ __typeof__(*(ptr)) __user *__p = (ptr); \
+ might_fault(); \
+ if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) { \
+ __p = uaccess_mask_ptr(__p); \
+ __put_user_err((x), __p, (err)); \
+ } else { \
+ (err) = -EFAULT; \
+ } \
+})
+
+#define __put_user_error(x, ptr, err) \
+({ \
+ __put_user_check((x), (ptr), (err)); \
+ (void)0; \
+})
+
+#define __put_user(x, ptr) \
+({ \
+ int __pu_err = 0; \
+ __put_user_check((x), (ptr), __pu_err); \
+ __pu_err; \
+})
+
+#define put_user __put_user
+
+extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
+#define raw_copy_from_user(to, from, n) \
+({ \
+ __arch_copy_from_user((to), __uaccess_mask_ptr(from), (n)); \
+})
+
+extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
+#define raw_copy_to_user(to, from, n) \
+({ \
+ __arch_copy_to_user(__uaccess_mask_ptr(to), (from), (n)); \
+})
+
+extern unsigned long __must_check __arch_copy_in_user(void __user *to, const void __user *from, unsigned long n);
+#define raw_copy_in_user(to, from, n) \
+({ \
+ __arch_copy_in_user(__uaccess_mask_ptr(to), \
+ __uaccess_mask_ptr(from), (n)); \
+})
+
+#define INLINE_COPY_TO_USER
+#define INLINE_COPY_FROM_USER
+
+extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
+static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
+{
+ if (access_ok(VERIFY_WRITE, to, n))
+ n = __arch_clear_user(__uaccess_mask_ptr(to), n);
+ return n;
+}
+#define clear_user __clear_user
+
+extern long strncpy_from_user(char *dest, const char __user *src, long count);
+
+extern __must_check long strnlen_user(const char __user *str, long n);
+
+#ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE
+struct page;
+void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len);
+extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n);
+
+static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size)
+{
+ kasan_check_write(dst, size);
+ return __copy_user_flushcache(dst, __uaccess_mask_ptr(src), size);
+}
+#endif
+
+#endif /* __ASM_UACCESS_H */
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-26 23:04:23 +0000