From: Max Filippov <jcmvbkbc@gmail.com>
To: linux-xtensa@linux-xtensa.org
Cc: Chris Zankel <chris@zankel.net>,
linux-kernel@vger.kernel.org, Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH 04/10] xtensa: don't use a12 in __xtensa_copy_user in call0 ABI
Date: Mon, 18 Oct 2021 22:17:10 -0700 [thread overview]
Message-ID: <20211019051716.4173-5-jcmvbkbc@gmail.com> (raw)
In-Reply-To: <20211019051716.4173-1-jcmvbkbc@gmail.com>
a12 is callee-saved register in xtensa call0 ABI, so a function must not
change it. The main unaligned copy loop of __xtensa_copy_user uses all
low-numbered registers, so a register must be spilled to avoid using a12
as a loop counter.
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
arch/xtensa/lib/usercopy.S | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/arch/xtensa/lib/usercopy.S b/arch/xtensa/lib/usercopy.S
index a0aa4047f94a..16128c094c62 100644
--- a/arch/xtensa/lib/usercopy.S
+++ b/arch/xtensa/lib/usercopy.S
@@ -60,7 +60,12 @@
.text
ENTRY(__xtensa_copy_user)
- abi_entry_default
+#if !XCHAL_HAVE_LOOPS && defined(__XTENSA_CALL0_ABI__)
+#define STACK_SIZE 4
+#else
+#define STACK_SIZE 0
+#endif
+ abi_entry(STACK_SIZE)
# a2/ dst, a3/ src, a4/ len
mov a5, a2 # copy dst so that a2 is return value
mov a11, a4 # preserve original len for error case
@@ -75,7 +80,7 @@ ENTRY(__xtensa_copy_user)
__ssa8 a3 # set shift amount from byte offset
bnez a4, .Lsrcunaligned
movi a2, 0 # return success for len==0
- abi_ret_default
+ abi_ret(STACK_SIZE)
/*
* Destination is unaligned
@@ -127,7 +132,7 @@ EX(10f) s8i a6, a5, 0
#endif /* !XCHAL_HAVE_LOOPS */
.Lbytecopydone:
movi a2, 0 # return success for len bytes copied
- abi_ret_default
+ abi_ret(STACK_SIZE)
/*
* Destination and source are word-aligned.
@@ -187,7 +192,7 @@ EX(10f) l8ui a6, a3, 0
EX(10f) s8i a6, a5, 0
.L5:
movi a2, 0 # return success for len bytes copied
- abi_ret_default
+ abi_ret(STACK_SIZE)
/*
* Destination is aligned, Source is unaligned
@@ -205,8 +210,14 @@ EX(10f) l32i a6, a3, 0 # load first word
loopnez a7, .Loop2done
#else /* !XCHAL_HAVE_LOOPS */
beqz a7, .Loop2done
+#if defined(__XTENSA_CALL0_ABI__)
+ s32i a10, a1, 0
+ slli a10, a7, 4
+ add a10, a10, a3 # a10 = end of last 16B source chunk
+#else
slli a12, a7, 4
add a12, a12, a3 # a12 = end of last 16B source chunk
+#endif
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2:
EX(10f) l32i a7, a3, 4
@@ -224,7 +235,12 @@ EX(10f) s32i a8, a5, 8
EX(10f) s32i a9, a5, 12
addi a5, a5, 16
#if !XCHAL_HAVE_LOOPS
+#if defined(__XTENSA_CALL0_ABI__)
+ blt a3, a10, .Loop2
+ l32i a10, a1, 0
+#else
blt a3, a12, .Loop2
+#endif
#endif /* !XCHAL_HAVE_LOOPS */
.Loop2done:
bbci.l a4, 3, .L12
@@ -264,7 +280,7 @@ EX(10f) l8ui a6, a3, 0
EX(10f) s8i a6, a5, 0
.L15:
movi a2, 0 # return success for len bytes copied
- abi_ret_default
+ abi_ret(STACK_SIZE)
ENDPROC(__xtensa_copy_user)
@@ -281,4 +297,4 @@ ENDPROC(__xtensa_copy_user)
10:
sub a2, a5, a2 /* a2 <-- bytes copied */
sub a2, a11, a2 /* a2 <-- bytes not copied */
- abi_ret_default
+ abi_ret(STACK_SIZE)
--
2.20.1
next prev parent reply other threads:[~2021-10-19 5:17 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 5:17 [PATCH 00/10] xtensa: support call0 ABI kernel Max Filippov
2021-10-19 5:17 ` [PATCH 01/10] xtensa: move _SimulateUserKernelVectorException out of WindowVectors Max Filippov
2021-10-19 5:17 ` [PATCH 02/10] xtensa: use a14 instead of a15 in inline assembly Max Filippov
2021-10-19 5:17 ` [PATCH 03/10] xtensa: don't use a12 in strncpy_user Max Filippov
2021-10-19 5:17 ` Max Filippov [this message]
2021-10-19 5:17 ` [PATCH 05/10] xtensa: definitions for call0 ABI Max Filippov
2021-10-19 5:17 ` [PATCH 06/10] xtensa: implement call0 ABI support in assembly Max Filippov
2021-10-19 5:17 ` [PATCH 07/10] xtensa: use register window specific opcodes only when present Max Filippov
2021-10-19 5:17 ` [PATCH 08/10] xtensa: only build windowed register support code when needed Max Filippov
2021-10-19 5:17 ` [PATCH 09/10] xtensa: remove unused variable wmask Max Filippov
2021-10-19 5:17 ` [PATCH 10/10] xtensa: move section symbols to asm/sections.h Max Filippov
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