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arm: propagate the calling convention changes down to csum_partial_copy_from_user()

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... and get rid of the "clean the destination on error" crap.
Simplifies the fault handlers and the function itself...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2020-07-12 22:56:34 -04:00
parent b712139543
commit 1d60be3c25
4 changed files with 9 additions and 26 deletions
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7
arch/arm/include/asm/checksum.h
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@ -38,20 +38,17 @@ __wsum
csum_partial_copy_nocheck(const void *src, void *dst, int len); csum_partial_copy_nocheck(const void *src, void *dst, int len);
__wsum __wsum
csum_partial_copy_from_user(const void __user *src, void *dst, int len, __wsum sum, int *err_ptr); csum_partial_copy_from_user(const void __user *src, void *dst, int len);
#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER #define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
#define _HAVE_ARCH_CSUM_AND_COPY #define _HAVE_ARCH_CSUM_AND_COPY
static inline static inline
__wsum csum_and_copy_from_user(const void __user *src, void *dst, int len) __wsum csum_and_copy_from_user(const void __user *src, void *dst, int len)
{ {
int err = 0;
if (!access_ok(src, len)) if (!access_ok(src, len))
return 0; return 0;
sum = csum_partial_copy_from_user(src, dst, len, ~0U, &err); return csum_partial_copy_from_user(src, dst, len);
return err ? 0 : sum;
} }
/* /*

1
arch/arm/lib/csumpartialcopy.S
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@ -16,7 +16,6 @@
.macro save_regs .macro save_regs
stmfd sp!, {r1, r4 - r8, lr} stmfd sp!, {r1, r4 - r8, lr}
mov r3, #0
.endm .endm
.macro load_regs .macro load_regs

1
arch/arm/lib/csumpartialcopygeneric.S
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@ -86,6 +86,7 @@ sum .req r3
FN_ENTRY FN_ENTRY
save_regs save_regs
mov sum, #-1
cmp len, #8 @ Ensure that we have at least cmp len, #8 @ Ensure that we have at least
blo .Lless8 @ 8 bytes to copy. blo .Lless8 @ 8 bytes to copy.

26
arch/arm/lib/csumpartialcopyuser.S
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@ -62,9 +62,9 @@
/* /*
* unsigned int * unsigned int
* csum_partial_copy_from_user(const char *src, char *dst, int len, int sum, int *err_ptr) * csum_partial_copy_from_user(const char *src, char *dst, int len)
* r0 = src, r1 = dst, r2 = len, r3 = sum, [sp] = *err_ptr * r0 = src, r1 = dst, r2 = len
* Returns : r0 = checksum, [[sp, #0], #0] = 0 or -EFAULT * Returns : r0 = checksum or 0
*/ */
#define FN_ENTRY ENTRY(csum_partial_copy_from_user) #define FN_ENTRY ENTRY(csum_partial_copy_from_user)
@ -73,25 +73,11 @@
#include "csumpartialcopygeneric.S" #include "csumpartialcopygeneric.S"
/* /*
* FIXME: minor buglet here * We report fault by returning 0 csum - impossible in normal case, since
* We don't return the checksum for the data present in the buffer. To do * we start with 0xffffffff for initial sum.
* so properly, we would have to add in whatever registers were loaded before
* the fault, which, with the current asm above is not predictable.
*/ */
.pushsection .text.fixup,"ax" .pushsection .text.fixup,"ax"
.align 4 .align 4
9001: mov r4, #-EFAULT 9001: mov r0, #0
#ifdef CONFIG_CPU_SW_DOMAIN_PAN
ldr r5, [sp, #9*4] @ *err_ptr
#else
ldr r5, [sp, #8*4] @ *err_ptr
#endif
str r4, [r5]
ldmia sp, {r1, r2} @ retrieve dst, len
add r2, r2, r1
mov r0, #0 @ zero the buffer
9002: teq r2, r1
strbne r0, [r1], #1
bne 9002b
load_regs load_regs
.popsection .popsection