[PATCH 5.4 68/87] x86: get rid of small constant size cases in raw_copy_{to,from}_user()

Greg Kroah-Hartman
2022-07-27T16:44:47Z

From: Al Viro <viro@zeniv.linux.org.uk>

[ Upstream commit 4b842e4e25b12951fa10dedb4bc16bc47e3b850c ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/include/asm/uaccess.h | 12 ----
arch/x86/include/asm/uaccess_32.h | 27 --------
arch/x86/include/asm/uaccess_64.h | 108 +-----------------------------
3 files changed, 2 insertions(+), 145 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 61d93f062a36..a19effb98fdc 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -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.
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index ba2dc1930630..388a40660c7b 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -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);
}

diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 5cd1caa8bc65..bc10e3dc64fe 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -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
--
2.35.1