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Message-Id: <20200724012546.302155-20-viro@ZenIV.linux.org.uk>
Date: Fri, 24 Jul 2020 02:25:46 +0100
From: Al Viro <viro@...IV.linux.org.uk>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: [PATCH v2 20/20] ppc: propagate the calling conventions change down to csum_partial_copy_generic()
From: Al Viro <viro@...iv.linux.org.uk>
... and get rid of the pointless fallback in the wrappers. On error it used
to zero the unwritten area and calculate the csum of the entire thing. Not
wanting to do it in assembler part had been very reasonable; doing that in
the first place, OTOH... In case of an error the caller discards the data
we'd copied, along with whatever checksum it might've had.
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
arch/powerpc/include/asm/checksum.h | 6 +--
arch/powerpc/lib/checksum_32.S | 74 +++++++++++++-----------------------
arch/powerpc/lib/checksum_64.S | 37 ++++++------------
arch/powerpc/lib/checksum_wrappers.c | 32 +++-------------
4 files changed, 46 insertions(+), 103 deletions(-)
diff --git a/arch/powerpc/include/asm/checksum.h b/arch/powerpc/include/asm/checksum.h
index dba685d984c0..82f099ba2411 100644
--- a/arch/powerpc/include/asm/checksum.h
+++ b/arch/powerpc/include/asm/checksum.h
@@ -18,9 +18,7 @@
* Like csum_partial, this must be called with even lengths,
* except for the last fragment.
*/
-extern __wsum csum_partial_copy_generic(const void *src, void *dst,
- int len, __wsum sum,
- int *src_err, int *dst_err);
+extern __wsum csum_partial_copy_generic(const void *src, void *dst, int len);
#define _HAVE_ARCH_COPY_AND_CSUM_FROM_USER
extern __wsum csum_and_copy_from_user(const void __user *src, void *dst,
@@ -31,7 +29,7 @@ extern __wsum csum_and_copy_to_user(const void *src, void __user *dst,
#define _HAVE_ARCH_CSUM_AND_COPY
#define csum_partial_copy_nocheck(src, dst, len) \
- csum_partial_copy_generic((src), (dst), (len), 0, NULL, NULL)
+ csum_partial_copy_generic((src), (dst), (len))
/*
diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index ecd150dc3ed9..ec5cd2dede35 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -78,12 +78,10 @@ EXPORT_SYMBOL(__csum_partial)
/*
* Computes the checksum of a memory block at src, length len,
- * and adds in "sum" (32-bit), while copying the block to dst.
- * If an access exception occurs on src or dst, it stores -EFAULT
- * to *src_err or *dst_err respectively, and (for an error on
- * src) zeroes the rest of dst.
+ * and adds in 0xffffffff, while copying the block to dst.
+ * If an access exception occurs it returns zero.
*
- * csum_partial_copy_generic(src, dst, len, sum, src_err, dst_err)
+ * csum_partial_copy_generic(src, dst, len)
*/
#define CSUM_COPY_16_BYTES_WITHEX(n) \
8 ## n ## 0: \
@@ -108,14 +106,14 @@ EXPORT_SYMBOL(__csum_partial)
adde r12,r12,r10
#define CSUM_COPY_16_BYTES_EXCODE(n) \
- EX_TABLE(8 ## n ## 0b, src_error); \
- EX_TABLE(8 ## n ## 1b, src_error); \
- EX_TABLE(8 ## n ## 2b, src_error); \
- EX_TABLE(8 ## n ## 3b, src_error); \
- EX_TABLE(8 ## n ## 4b, dst_error); \
- EX_TABLE(8 ## n ## 5b, dst_error); \
- EX_TABLE(8 ## n ## 6b, dst_error); \
- EX_TABLE(8 ## n ## 7b, dst_error);
+ EX_TABLE(8 ## n ## 0b, fault); \
+ EX_TABLE(8 ## n ## 1b, fault); \
+ EX_TABLE(8 ## n ## 2b, fault); \
+ EX_TABLE(8 ## n ## 3b, fault); \
+ EX_TABLE(8 ## n ## 4b, fault); \
+ EX_TABLE(8 ## n ## 5b, fault); \
+ EX_TABLE(8 ## n ## 6b, fault); \
+ EX_TABLE(8 ## n ## 7b, fault);
.text
.stabs "arch/powerpc/lib/",N_SO,0,0,0f
@@ -127,11 +125,8 @@ LG_CACHELINE_BYTES = L1_CACHE_SHIFT
CACHELINE_MASK = (L1_CACHE_BYTES-1)
_GLOBAL(csum_partial_copy_generic)
- stwu r1,-16(r1)
- stw r7,12(r1)
- stw r8,8(r1)
-
- addic r12,r6,0
+ li r12,-1
+ addic r0,r0,0 /* clear carry */
addi r6,r4,-4
neg r0,r4
addi r4,r3,-4
@@ -246,34 +241,19 @@ _GLOBAL(csum_partial_copy_generic)
rlwinm r3,r3,8,0,31 /* odd destination address: rotate one byte */
blr
-/* read fault */
-src_error:
- lwz r7,12(r1)
- addi r1,r1,16
- cmpwi cr0,r7,0
- beqlr
- li r0,-EFAULT
- stw r0,0(r7)
- blr
-/* write fault */
-dst_error:
- lwz r8,8(r1)
- addi r1,r1,16
- cmpwi cr0,r8,0
- beqlr
- li r0,-EFAULT
- stw r0,0(r8)
+fault:
+ li r3,0
blr
- EX_TABLE(70b, src_error);
- EX_TABLE(71b, dst_error);
- EX_TABLE(72b, src_error);
- EX_TABLE(73b, dst_error);
- EX_TABLE(54b, dst_error);
+ EX_TABLE(70b, fault);
+ EX_TABLE(71b, fault);
+ EX_TABLE(72b, fault);
+ EX_TABLE(73b, fault);
+ EX_TABLE(54b, fault);
/*
* this stuff handles faults in the cacheline loop and branches to either
- * src_error (if in read part) or dst_error (if in write part)
+ * fault (if in read part) or fault (if in write part)
*/
CSUM_COPY_16_BYTES_EXCODE(0)
#if L1_CACHE_BYTES >= 32
@@ -290,12 +270,12 @@ dst_error:
#endif
#endif
- EX_TABLE(30b, src_error);
- EX_TABLE(31b, dst_error);
- EX_TABLE(40b, src_error);
- EX_TABLE(41b, dst_error);
- EX_TABLE(50b, src_error);
- EX_TABLE(51b, dst_error);
+ EX_TABLE(30b, fault);
+ EX_TABLE(31b, fault);
+ EX_TABLE(40b, fault);
+ EX_TABLE(41b, fault);
+ EX_TABLE(50b, fault);
+ EX_TABLE(51b, fault);
EXPORT_SYMBOL(csum_partial_copy_generic)
diff --git a/arch/powerpc/lib/checksum_64.S b/arch/powerpc/lib/checksum_64.S
index 514978f908d4..98ff51bd2f7d 100644
--- a/arch/powerpc/lib/checksum_64.S
+++ b/arch/powerpc/lib/checksum_64.S
@@ -182,34 +182,33 @@ EXPORT_SYMBOL(__csum_partial)
.macro srcnr
100:
- EX_TABLE(100b,.Lsrc_error_nr)
+ EX_TABLE(100b,.Lerror_nr)
.endm
.macro source
150:
- EX_TABLE(150b,.Lsrc_error)
+ EX_TABLE(150b,.Lerror)
.endm
.macro dstnr
200:
- EX_TABLE(200b,.Ldest_error_nr)
+ EX_TABLE(200b,.Lerror_nr)
.endm
.macro dest
250:
- EX_TABLE(250b,.Ldest_error)
+ EX_TABLE(250b,.Lerror)
.endm
/*
* Computes the checksum of a memory block at src, length len,
- * and adds in "sum" (32-bit), while copying the block to dst.
- * If an access exception occurs on src or dst, it stores -EFAULT
- * to *src_err or *dst_err respectively. The caller must take any action
- * required in this case (zeroing memory, recalculating partial checksum etc).
+ * and adds in 0xffffffff (32-bit), while copying the block to dst.
+ * If an access exception occurs, it returns 0.
*
- * csum_partial_copy_generic(r3=src, r4=dst, r5=len, r6=sum, r7=src_err, r8=dst_err)
+ * csum_partial_copy_generic(r3=src, r4=dst, r5=len)
*/
_GLOBAL(csum_partial_copy_generic)
+ li r6,-1
addic r0,r6,0 /* clear carry */
srdi. r6,r5,3 /* less than 8 bytes? */
@@ -401,29 +400,15 @@ dstnr; stb r6,0(r4)
srdi r3,r3,32
blr
-.Lsrc_error:
+.Lerror:
ld r14,STK_REG(R14)(r1)
ld r15,STK_REG(R15)(r1)
ld r16,STK_REG(R16)(r1)
addi r1,r1,STACKFRAMESIZE
-.Lsrc_error_nr:
- cmpdi 0,r7,0
- beqlr
- li r6,-EFAULT
- stw r6,0(r7)
+.Lerror_nr:
+ li r3,0
blr
-.Ldest_error:
- ld r14,STK_REG(R14)(r1)
- ld r15,STK_REG(R15)(r1)
- ld r16,STK_REG(R16)(r1)
- addi r1,r1,STACKFRAMESIZE
-.Ldest_error_nr:
- cmpdi 0,r8,0
- beqlr
- li r6,-EFAULT
- stw r6,0(r8)
- blr
EXPORT_SYMBOL(csum_partial_copy_generic)
/*
diff --git a/arch/powerpc/lib/checksum_wrappers.c b/arch/powerpc/lib/checksum_wrappers.c
index b1faa82dd8af..b895166afc82 100644
--- a/arch/powerpc/lib/checksum_wrappers.c
+++ b/arch/powerpc/lib/checksum_wrappers.c
@@ -14,8 +14,7 @@
__wsum csum_and_copy_from_user(const void __user *src, void *dst,
int len)
{
- unsigned int csum;
- int err = 0;
+ __wsum csum;
might_sleep();
@@ -24,27 +23,16 @@ __wsum csum_and_copy_from_user(const void __user *src, void *dst,
allow_read_from_user(src, len);
- csum = csum_partial_copy_generic((void __force *)src, dst,
- len, ~0U, &err, NULL);
-
- if (unlikely(err)) {
- int missing = __copy_from_user(dst, src, len);
-
- if (missing)
- csum = 0;
- else
- csum = csum_partial(dst, len, ~0U);
- }
+ csum = csum_partial_copy_generic((void __force *)src, dst, len);
prevent_read_from_user(src, len);
- return (__force __wsum)csum;
+ return csum;
}
EXPORT_SYMBOL(csum_and_copy_from_user);
__wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
{
- unsigned int csum;
- int err = 0;
+ __wsum csum;
might_sleep();
if (unlikely(!access_ok(dst, len)))
@@ -52,17 +40,9 @@ __wsum csum_and_copy_to_user(const void *src, void __user *dst, int len)
allow_write_to_user(dst, len);
- csum = csum_partial_copy_generic(src, (void __force *)dst,
- len, ~0U, NULL, &err);
-
- if (unlikely(err)) {
- csum = csum_partial(src, len, ~0U);
-
- if (copy_to_user(dst, src, len))
- csum = 0;
- }
+ csum = csum_partial_copy_generic(src, (void __force *)dst, len);
prevent_write_to_user(dst, len);
- return (__force __wsum)csum;
+ return csum;
}
EXPORT_SYMBOL(csum_and_copy_to_user);
--
2.11.0
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