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x86: get rid of small constant size cases in raw_copy_{to,from}_user()
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Very few call sites where that would be triggered remain, and none
of those is anywhere near hot enough to bother.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro committed Mar 18, 2020
1 parent 71c3313 commit 4b842e4
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Showing 3 changed files with 2 additions and 145 deletions.
12 changes: 0 additions & 12 deletions arch/x86/include/asm/uaccess.h
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Original file line number Diff line number Diff line change
Expand Up @@ -378,18 +378,6 @@ do { \
: "=r" (err), ltype(x) \
: "m" (__m(addr)), "i" (errret), "0" (err))

#define __get_user_asm_nozero(x, addr, err, itype, rtype, ltype, errret) \
asm volatile("\n" \
"1: mov"itype" %2,%"rtype"1\n" \
"2:\n" \
".section .fixup,\"ax\"\n" \
"3: mov %3,%0\n" \
" jmp 2b\n" \
".previous\n" \
_ASM_EXTABLE_UA(1b, 3b) \
: "=r" (err), ltype(x) \
: "m" (__m(addr)), "i" (errret), "0" (err))

/*
* This doesn't do __uaccess_begin/end - the exception handling
* around it must do that.
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27 changes: 0 additions & 27 deletions arch/x86/include/asm/uaccess_32.h
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Original file line number Diff line number Diff line change
Expand Up @@ -23,33 +23,6 @@ raw_copy_to_user(void __user *to, const void *from, unsigned long n)
static __always_inline unsigned long
raw_copy_from_user(void *to, const void __user *from, unsigned long n)
{
if (__builtin_constant_p(n)) {
unsigned long ret;

switch (n) {
case 1:
ret = 0;
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u8 *)to, from, ret,
"b", "b", "=q", 1);
__uaccess_end();
return ret;
case 2:
ret = 0;
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u16 *)to, from, ret,
"w", "w", "=r", 2);
__uaccess_end();
return ret;
case 4:
ret = 0;
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u32 *)to, from, ret,
"l", "k", "=r", 4);
__uaccess_end();
return ret;
}
}
return __copy_user_ll(to, (__force const void *)from, n);
}

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108 changes: 2 additions & 106 deletions arch/x86/include/asm/uaccess_64.h
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Original file line number Diff line number Diff line change
Expand Up @@ -65,117 +65,13 @@ copy_to_user_mcsafe(void *to, const void *from, unsigned len)
static __always_inline __must_check unsigned long
raw_copy_from_user(void *dst, const void __user *src, unsigned long size)
{
int ret = 0;

if (!__builtin_constant_p(size))
return copy_user_generic(dst, (__force void *)src, size);
switch (size) {
case 1:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u8 *)dst, (u8 __user *)src,
ret, "b", "b", "=q", 1);
__uaccess_end();
return ret;
case 2:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u16 *)dst, (u16 __user *)src,
ret, "w", "w", "=r", 2);
__uaccess_end();
return ret;
case 4:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u32 *)dst, (u32 __user *)src,
ret, "l", "k", "=r", 4);
__uaccess_end();
return ret;
case 8:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u64 *)dst, (u64 __user *)src,
ret, "q", "", "=r", 8);
__uaccess_end();
return ret;
case 10:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u64 *)dst, (u64 __user *)src,
ret, "q", "", "=r", 10);
if (likely(!ret))
__get_user_asm_nozero(*(u16 *)(8 + (char *)dst),
(u16 __user *)(8 + (char __user *)src),
ret, "w", "w", "=r", 2);
__uaccess_end();
return ret;
case 16:
__uaccess_begin_nospec();
__get_user_asm_nozero(*(u64 *)dst, (u64 __user *)src,
ret, "q", "", "=r", 16);
if (likely(!ret))
__get_user_asm_nozero(*(u64 *)(8 + (char *)dst),
(u64 __user *)(8 + (char __user *)src),
ret, "q", "", "=r", 8);
__uaccess_end();
return ret;
default:
return copy_user_generic(dst, (__force void *)src, size);
}
return copy_user_generic(dst, (__force void *)src, size);
}

static __always_inline __must_check unsigned long
raw_copy_to_user(void __user *dst, const void *src, unsigned long size)
{
int ret = 0;

if (!__builtin_constant_p(size))
return copy_user_generic((__force void *)dst, src, size);
switch (size) {
case 1:
__uaccess_begin();
__put_user_asm(*(u8 *)src, (u8 __user *)dst,
ret, "b", "b", "iq", 1);
__uaccess_end();
return ret;
case 2:
__uaccess_begin();
__put_user_asm(*(u16 *)src, (u16 __user *)dst,
ret, "w", "w", "ir", 2);
__uaccess_end();
return ret;
case 4:
__uaccess_begin();
__put_user_asm(*(u32 *)src, (u32 __user *)dst,
ret, "l", "k", "ir", 4);
__uaccess_end();
return ret;
case 8:
__uaccess_begin();
__put_user_asm(*(u64 *)src, (u64 __user *)dst,
ret, "q", "", "er", 8);
__uaccess_end();
return ret;
case 10:
__uaccess_begin();
__put_user_asm(*(u64 *)src, (u64 __user *)dst,
ret, "q", "", "er", 10);
if (likely(!ret)) {
asm("":::"memory");
__put_user_asm(4[(u16 *)src], 4 + (u16 __user *)dst,
ret, "w", "w", "ir", 2);
}
__uaccess_end();
return ret;
case 16:
__uaccess_begin();
__put_user_asm(*(u64 *)src, (u64 __user *)dst,
ret, "q", "", "er", 16);
if (likely(!ret)) {
asm("":::"memory");
__put_user_asm(1[(u64 *)src], 1 + (u64 __user *)dst,
ret, "q", "", "er", 8);
}
__uaccess_end();
return ret;
default:
return copy_user_generic((__force void *)dst, src, size);
}
return copy_user_generic((__force void *)dst, src, size);
}

static __always_inline __must_check
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