[PATCH 5.4 028/215] parisc: Do not hardcode registers in checksum functions

Greg Kroah-Hartman
2024-04-11T10:17:17Z

From: Helge Deller <deller@gmx.de>

[ Upstream commit 52b2d91752a82d9350981eb3b3ffc4b325c84ba9 ]

Do not hardcode processor registers r19 to r22 as scratch registers.
Instead let the compiler decide, which may give better optimization
results when the functions get inlined.

Signed-off-by: Helge Deller <deller@gmx.de>
Stable-dep-of: a2abae8f0b63 ("parisc: Fix ip_fast_csum")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/parisc/include/asm/checksum.h | 101 +++++++++++++++--------------
1 file changed, 52 insertions(+), 49 deletions(-)

diff --git a/arch/parisc/include/asm/checksum.h b/arch/parisc/include/asm/checksum.h
index 3cbf1f1c1188e..c1c22819a04d1 100644
--- a/arch/parisc/include/asm/checksum.h
+++ b/arch/parisc/include/asm/checksum.h
@@ -42,31 +42,32 @@ extern __wsum csum_partial_copy_from_user(const void __user *src,
static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl)
{
unsigned int sum;
+ unsigned long t0, t1, t2;

__asm__ __volatile__ (
" ldws,ma 4(%1), %0\n"
" addib,<= -4, %2, 2f\n"
"\n"
-" ldws 4(%1), %%r20\n"
-" ldws 8(%1), %%r21\n"
-" add %0, %%r20, %0\n"
-" ldws,ma 12(%1), %%r19\n"
-" addc %0, %%r21, %0\n"
-" addc %0, %%r19, %0\n"
-"1: ldws,ma 4(%1), %%r19\n"
+" ldws 4(%1), %4\n"
+" ldws 8(%1), %5\n"
+" add %0, %4, %0\n"
+" ldws,ma 12(%1), %3\n"
+" addc %0, %5, %0\n"
+" addc %0, %3, %0\n"
+"1: ldws,ma 4(%1), %3\n"
" addib,< 0, %2, 1b\n"
-" addc %0, %%r19, %0\n"
+" addc %0, %3, %0\n"
"\n"
-" extru %0, 31, 16, %%r20\n"
-" extru %0, 15, 16, %%r21\n"
-" addc %%r20, %%r21, %0\n"
-" extru %0, 15, 16, %%r21\n"
-" add %0, %%r21, %0\n"
+" extru %0, 31, 16, %4\n"
+" extru %0, 15, 16, %5\n"
+" addc %4, %5, %0\n"
+" extru %0, 15, 16, %5\n"
+" add %0, %5, %0\n"
" subi -1, %0, %0\n"
"2:\n"
- : "=r" (sum), "=r" (iph), "=r" (ihl)
+ : "=r" (sum), "=r" (iph), "=r" (ihl), "=r" (t0), "=r" (t1), "=r" (t2)
: "1" (iph), "2" (ihl)
- : "r19", "r20", "r21", "memory");
+ : "memory");

return (__force __sum16)sum;
}
@@ -126,6 +127,10 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
__u32 len, __u8 proto,
__wsum sum)
{
+ unsigned long t0, t1, t2, t3;
+
+ len += proto; /* add 16-bit proto + len */
+
__asm__ __volatile__ (

#if BITS_PER_LONG > 32
@@ -136,20 +141,19 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
** Try to keep 4 registers with "live" values ahead of the ALU.
*/

-" ldd,ma 8(%1), %%r19\n" /* get 1st saddr word */
-" ldd,ma 8(%2), %%r20\n" /* get 1st daddr word */
-" add %8, %3, %3\n"/* add 16-bit proto + len */
-" add %%r19, %0, %0\n"
-" ldd,ma 8(%1), %%r21\n" /* 2cd saddr */
-" ldd,ma 8(%2), %%r22\n" /* 2cd daddr */
-" add,dc %%r20, %0, %0\n"
-" add,dc %%r21, %0, %0\n"
-" add,dc %%r22, %0, %0\n"
+" ldd,ma 8(%1), %4\n" /* get 1st saddr word */
+" ldd,ma 8(%2), %5\n" /* get 1st daddr word */
+" add %4, %0, %0\n"
+" ldd,ma 8(%1), %6\n" /* 2nd saddr */
+" ldd,ma 8(%2), %7\n" /* 2nd daddr */
+" add,dc %5, %0, %0\n"
+" add,dc %6, %0, %0\n"
+" add,dc %7, %0, %0\n"
" add,dc %3, %0, %0\n" /* fold in proto+len | carry bit */
-" extrd,u %0, 31, 32, %%r19\n" /* copy upper half down */
-" depdi 0, 31, 32, %0\n" /* clear upper half */
-" add %%r19, %0, %0\n" /* fold into 32-bits */
-" addc 0, %0, %0\n" /* add carry */
+" extrd,u %0, 31, 32, %4\n"/* copy upper half down */
+" depdi 0, 31, 32, %0\n"/* clear upper half */
+" add %4, %0, %0\n" /* fold into 32-bits */
+" addc 0, %0, %0\n" /* add carry */

#else

@@ -158,30 +162,29 @@ static __inline__ __sum16 csum_ipv6_magic(const struct in6_addr *saddr,
** Insn stream is serialized on the carry bit here too.
** result from the previous operation (eg r0 + x)
*/
-
-" ldw,ma 4(%1), %%r19\n" /* get 1st saddr word */
-" ldw,ma 4(%2), %%r20\n" /* get 1st daddr word */
-" add %8, %3, %3\n" /* add 16-bit proto + len */
-" add %%r19, %0, %0\n"
-" ldw,ma 4(%1), %%r21\n" /* 2cd saddr */
-" addc %%r20, %0, %0\n"
-" ldw,ma 4(%2), %%r22\n" /* 2cd daddr */
-" addc %%r21, %0, %0\n"
-" ldw,ma 4(%1), %%r19\n" /* 3rd saddr */
-" addc %%r22, %0, %0\n"
-" ldw,ma 4(%2), %%r20\n" /* 3rd daddr */
-" addc %%r19, %0, %0\n"
-" ldw,ma 4(%1), %%r21\n" /* 4th saddr */
-" addc %%r20, %0, %0\n"
-" ldw,ma 4(%2), %%r22\n" /* 4th daddr */
-" addc %%r21, %0, %0\n"
-" addc %%r22, %0, %0\n"
+" ldw,ma 4(%1), %4\n" /* get 1st saddr word */
+" ldw,ma 4(%2), %5\n" /* get 1st daddr word */
+" add %4, %0, %0\n"
+" ldw,ma 4(%1), %6\n" /* 2nd saddr */
+" addc %5, %0, %0\n"
+" ldw,ma 4(%2), %7\n" /* 2nd daddr */
+" addc %6, %0, %0\n"
+" ldw,ma 4(%1), %4\n" /* 3rd saddr */
+" addc %7, %0, %0\n"
+" ldw,ma 4(%2), %5\n" /* 3rd daddr */
+" addc %4, %0, %0\n"
+" ldw,ma 4(%1), %6\n" /* 4th saddr */
+" addc %5, %0, %0\n"
+" ldw,ma 4(%2), %7\n" /* 4th daddr */
+" addc %6, %0, %0\n"
+" addc %7, %0, %0\n"
" addc %3, %0, %0\n" /* fold in proto+len, catch carry */

#endif
- : "=r" (sum), "=r" (saddr), "=r" (daddr), "=r" (len)
- : "0" (sum), "1" (saddr), "2" (daddr), "3" (len), "r" (proto)
- : "r19", "r20", "r21", "r22", "memory");
+ : "=r" (sum), "=r" (saddr), "=r" (daddr), "=r" (len),
+ "=r" (t0), "=r" (t1), "=r" (t2), "=r" (t3)
+ : "0" (sum), "1" (saddr), "2" (daddr), "3" (len)
+ : "memory");
return csum_fold(sum);
}

--
2.43.0