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riscv: Less inefficient gcc tishift helpers (and export their symbols)

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The existing __lshrti3 was really inefficient, and the other two helpers
are also needed to compile some modules.

Add the missing versions, and export all of the symbols like arm64
already does.

This code is based on the assembly generated by libgcc builds.

This fixes a build break triggered by ubsan:

riscv64-unknown-linux-gnu-ld: lib/ubsan.o: in function `.L2':
ubsan.c:(.text.unlikely+0x38): undefined reference to `__ashlti3'
riscv64-unknown-linux-gnu-ld: ubsan.c:(.text.unlikely+0x42): undefined reference to `__ashrti3'

Signed-off-by: Olof Johansson <olof@lixom.net>
[paul.walmsley@sifive.com: use SYM_FUNC_{START,END} instead of
 ENTRY/ENDPROC; note libgcc origin]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
This commit is contained in:
Olof Johansson 2019-12-16 20:06:31 -08:00 committed by Paul Walmsley
parent 95f4d9cced
commit fc585d4a5c
2 changed files with 61 additions and 18 deletions
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4
arch/riscv/include/asm/asm-prototypes.h
View File

@ -5,4 +5,8 @@
#include <linux/ftrace.h>
#include <asm-generic/asm-prototypes.h>
long long __lshrti3(long long a, int b);
long long __ashrti3(long long a, int b);
long long __ashlti3(long long a, int b);
#endif /* _ASM_RISCV_PROTOTYPES_H */

75
arch/riscv/lib/tishift.S
View File

@ -4,34 +4,73 @@
*/
#include <linux/linkage.h>
#include <asm-generic/export.h>
ENTRY(__lshrti3)
SYM_FUNC_START(__lshrti3)
beqz a2, .L1
li a5,64
sub a5,a5,a2
addi sp,sp,-16
sext.w a4,a5
blez a5, .L2
sext.w a2,a2
sll a4,a1,a4
srl a0,a0,a2
srl a1,a1,a2
sll a4,a1,a4
srl a2,a1,a2
or a0,a0,a4
sd a1,8(sp)
sd a0,0(sp)
ld a0,0(sp)
ld a1,8(sp)
addi sp,sp,16
ret
mv a1,a2
.L1:
ret
.L2:
negw a4,a4
srl a1,a1,a4
sd a1,0(sp)
sd zero,8(sp)
ld a0,0(sp)
ld a1,8(sp)
addi sp,sp,16
negw a0,a4
li a2,0
srl a0,a1,a0
mv a1,a2
ret
ENDPROC(__lshrti3)
SYM_FUNC_END(__lshrti3)
EXPORT_SYMBOL(__lshrti3)
SYM_FUNC_START(__ashrti3)
beqz a2, .L3
li a5,64
sub a5,a5,a2
sext.w a4,a5
blez a5, .L4
sext.w a2,a2
srl a0,a0,a2
sll a4,a1,a4
sra a2,a1,a2
or a0,a0,a4
mv a1,a2
.L3:
ret
.L4:
negw a0,a4
srai a2,a1,0x3f
sra a0,a1,a0
mv a1,a2
ret
SYM_FUNC_END(__ashrti3)
EXPORT_SYMBOL(__ashrti3)
SYM_FUNC_START(__ashlti3)
beqz a2, .L5
li a5,64
sub a5,a5,a2
sext.w a4,a5
blez a5, .L6
sext.w a2,a2
sll a1,a1,a2
srl a4,a0,a4
sll a2,a0,a2
or a1,a1,a4
mv a0,a2
.L5:
ret
.L6:
negw a1,a4
li a2,0
sll a1,a0,a1
mv a0,a2
ret
SYM_FUNC_END(__ashlti3)
EXPORT_SYMBOL(__ashlti3)