riscv: extable: add a dedicated uaccess handler
Inspired by commit 2e77a62cb3 ("arm64: extable: add a dedicated
uaccess handler"), do similar to riscv to add a dedicated uaccess
exception handler to update registers in exception context and
subsequently return back into the function which faulted, so we remove
the need for fixups specialized to each faulting instruction.
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Jisheng Zhang
Palmer Dabbelt
parent
ff4b8cad3a
commit
20802d8d47
@ -5,6 +5,7 @@
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#define EX_TYPE_NONE 0
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#define EX_TYPE_FIXUP 1
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#define EX_TYPE_BPF 2
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#define EX_TYPE_UACCESS_ERR_ZERO 3
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#ifdef __ASSEMBLY__
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@ -23,7 +24,9 @@
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#else /* __ASSEMBLY__ */
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#include <linux/bits.h>
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#include <linux/stringify.h>
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#include <asm/gpr-num.h>
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#define __ASM_EXTABLE_RAW(insn, fixup, type, data) \
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".pushsection __ex_table, \"a\"\n" \
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@ -37,6 +40,26 @@
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#define _ASM_EXTABLE(insn, fixup) \
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__ASM_EXTABLE_RAW(#insn, #fixup, __stringify(EX_TYPE_FIXUP), "0")
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#define EX_DATA_REG_ERR_SHIFT 0
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#define EX_DATA_REG_ERR GENMASK(4, 0)
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#define EX_DATA_REG_ZERO_SHIFT 5
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#define EX_DATA_REG_ZERO GENMASK(9, 5)
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#define EX_DATA_REG(reg, gpr) \
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"((.L__gpr_num_" #gpr ") << " __stringify(EX_DATA_REG_##reg##_SHIFT) ")"
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#define _ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero) \
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__DEFINE_ASM_GPR_NUMS \
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__ASM_EXTABLE_RAW(#insn, #fixup, \
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__stringify(EX_TYPE_UACCESS_ERR_ZERO), \
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"(" \
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EX_DATA_REG(ERR, err) " | " \
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EX_DATA_REG(ZERO, zero) \
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")")
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#define _ASM_EXTABLE_UACCESS_ERR(insn, fixup, err) \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(insn, fixup, err, zero)
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#endif /* __ASSEMBLY__ */
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#endif /* __ASM_ASM_EXTABLE_H */
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@ -21,20 +21,14 @@
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#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
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{ \
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uintptr_t tmp; \
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__enable_user_access(); \
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__asm__ __volatile__ ( \
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"1: " insn " \n" \
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"2: \n" \
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" .section .fixup,\"ax\" \n" \
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" .balign 4 \n" \
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"3: li %[r],%[e] \n" \
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" jump 2b,%[t] \n" \
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" .previous \n" \
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_ASM_EXTABLE(1b, 3b) \
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_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %[r]) \
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: [r] "+r" (ret), [ov] "=&r" (oldval), \
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[u] "+m" (*uaddr), [t] "=&r" (tmp) \
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: [op] "Jr" (oparg), [e] "i" (-EFAULT) \
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[u] "+m" (*uaddr) \
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: [op] "Jr" (oparg) \
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: "memory"); \
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__disable_user_access(); \
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}
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@ -96,15 +90,10 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
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"2: sc.w.aqrl %[t],%z[nv],%[u] \n"
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" bnez %[t],1b \n"
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"3: \n"
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" .section .fixup,\"ax\" \n"
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" .balign 4 \n"
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"4: li %[r],%[e] \n"
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" jump 3b,%[t] \n"
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" .previous \n"
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_ASM_EXTABLE(1b, 4b) \
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_ASM_EXTABLE(2b, 4b) \
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_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r]) \
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_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r]) \
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: [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp)
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: [ov] "Jr" (oldval), [nv] "Jr" (newval), [e] "i" (-EFAULT)
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: [ov] "Jr" (oldval), [nv] "Jr" (newval)
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: "memory");
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__disable_user_access();
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@ -81,22 +81,14 @@ static inline int __access_ok(unsigned long addr, unsigned long size)
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#define __get_user_asm(insn, x, ptr, err) \
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do { \
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uintptr_t __tmp; \
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__typeof__(x) __x; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" " insn " %1, %3\n" \
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" " insn " %1, %2\n" \
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"2:\n" \
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" .section .fixup,\"ax\"\n" \
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" .balign 4\n" \
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"3:\n" \
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" li %0, %4\n" \
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" li %1, 0\n" \
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" jump 2b, %2\n" \
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" .previous\n" \
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_ASM_EXTABLE(1b, 3b) \
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: "+r" (err), "=&r" (__x), "=r" (__tmp) \
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: "m" (*(ptr)), "i" (-EFAULT)); \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 2b, %0, %1) \
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: "+r" (err), "=&r" (__x) \
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: "m" (*(ptr))); \
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(x) = __x; \
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} while (0)
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@ -108,27 +100,18 @@ do { \
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do { \
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u32 __user *__ptr = (u32 __user *)(ptr); \
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u32 __lo, __hi; \
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uintptr_t __tmp; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" lw %1, %4\n" \
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" lw %1, %3\n" \
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"2:\n" \
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" lw %2, %5\n" \
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" lw %2, %4\n" \
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"3:\n" \
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" .section .fixup,\"ax\"\n" \
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" .balign 4\n" \
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"4:\n" \
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" li %0, %6\n" \
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" li %1, 0\n" \
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" li %2, 0\n" \
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" jump 3b, %3\n" \
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" .previous\n" \
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_ASM_EXTABLE(1b, 4b) \
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_ASM_EXTABLE(2b, 4b) \
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: "+r" (err), "=&r" (__lo), "=r" (__hi), \
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"=r" (__tmp) \
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: "m" (__ptr[__LSW]), "m" (__ptr[__MSW]), \
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"i" (-EFAULT)); \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(1b, 3b, %0, %1) \
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_ASM_EXTABLE_UACCESS_ERR_ZERO(2b, 3b, %0, %1) \
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: "+r" (err), "=&r" (__lo), "=r" (__hi) \
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: "m" (__ptr[__LSW]), "m" (__ptr[__MSW])); \
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if (err) \
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__hi = 0; \
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(x) = (__typeof__(x))((__typeof__((x)-(x)))( \
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(((u64)__hi << 32) | __lo))); \
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} while (0)
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@ -216,21 +199,14 @@ do { \
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#define __put_user_asm(insn, x, ptr, err) \
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do { \
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uintptr_t __tmp; \
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__typeof__(*(ptr)) __x = x; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" " insn " %z3, %2\n" \
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" " insn " %z2, %1\n" \
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"2:\n" \
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" .section .fixup,\"ax\"\n" \
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" .balign 4\n" \
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"3:\n" \
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" li %0, %4\n" \
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" jump 2b, %1\n" \
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" .previous\n" \
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_ASM_EXTABLE(1b, 3b) \
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: "+r" (err), "=r" (__tmp), "=m" (*(ptr)) \
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: "rJ" (__x), "i" (-EFAULT)); \
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_ASM_EXTABLE_UACCESS_ERR(1b, 2b, %0) \
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: "+r" (err), "=m" (*(ptr)) \
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: "rJ" (__x)); \
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} while (0)
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#ifdef CONFIG_64BIT
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@ -241,25 +217,18 @@ do { \
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do { \
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u32 __user *__ptr = (u32 __user *)(ptr); \
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u64 __x = (__typeof__((x)-(x)))(x); \
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uintptr_t __tmp; \
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__asm__ __volatile__ ( \
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"1:\n" \
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" sw %z4, %2\n" \
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" sw %z3, %1\n" \
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"2:\n" \
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" sw %z5, %3\n" \
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" sw %z4, %2\n" \
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"3:\n" \
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" .section .fixup,\"ax\"\n" \
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" .balign 4\n" \
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"4:\n" \
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" li %0, %6\n" \
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" jump 3b, %1\n" \
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" .previous\n" \
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_ASM_EXTABLE(1b, 4b) \
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_ASM_EXTABLE(2b, 4b) \
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: "+r" (err), "=r" (__tmp), \
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_ASM_EXTABLE_UACCESS_ERR(1b, 3b, %0) \
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_ASM_EXTABLE_UACCESS_ERR(2b, 3b, %0) \
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: "+r" (err), \
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"=m" (__ptr[__LSW]), \
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"=m" (__ptr[__MSW]) \
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: "rJ" (__x), "rJ" (__x >> 32), "i" (-EFAULT)); \
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: "rJ" (__x), "rJ" (__x >> 32)); \
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} while (0)
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#endif /* CONFIG_64BIT */
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@ -7,10 +7,12 @@
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*/
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#include <linux/bitfield.h>
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#include <linux/extable.h>
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#include <linux/module.h>
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#include <linux/uaccess.h>
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#include <asm/asm-extable.h>
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#include <asm/ptrace.h>
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static inline unsigned long
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get_ex_fixup(const struct exception_table_entry *ex)
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@ -25,6 +27,29 @@ static bool ex_handler_fixup(const struct exception_table_entry *ex,
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return true;
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}
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static inline void regs_set_gpr(struct pt_regs *regs, unsigned int offset,
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unsigned long val)
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{
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if (unlikely(offset > MAX_REG_OFFSET))
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return;
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if (!offset)
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*(unsigned long *)((unsigned long)regs + offset) = val;
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}
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static bool ex_handler_uaccess_err_zero(const struct exception_table_entry *ex,
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struct pt_regs *regs)
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{
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int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
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int reg_zero = FIELD_GET(EX_DATA_REG_ZERO, ex->data);
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regs_set_gpr(regs, reg_err, -EFAULT);
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regs_set_gpr(regs, reg_zero, 0);
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regs->epc = get_ex_fixup(ex);
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return true;
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}
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bool fixup_exception(struct pt_regs *regs)
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{
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const struct exception_table_entry *ex;
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@ -38,6 +63,8 @@ bool fixup_exception(struct pt_regs *regs)
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return ex_handler_fixup(ex, regs);
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case EX_TYPE_BPF:
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return ex_handler_bpf(ex, regs);
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case EX_TYPE_UACCESS_ERR_ZERO:
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return ex_handler_uaccess_err_zero(ex, regs);
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}
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BUG();
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