[PATCH 5.4 239/240] riscv: Less inefficient gcc tishift helpers (and export their symbols)

Greg Kroah-Hartman
2022-06-20T14:07:07Z

From: Olof Johansson <olof@lixom.net>

commit fc585d4a5cf614727f64d86550b794bcad29d5c3 upstream.

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>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/riscv/include/asm/asm-prototypes.h | 4 +
arch/riscv/lib/tishift.S | 75 ++++++++++++++++++++++++--------
2 files changed, 61 insertions(+), 18 deletions(-)

--- a/arch/riscv/include/asm/asm-prototypes.h
+++ b/arch/riscv/include/asm/asm-prototypes.h
@@ -4,4 +4,8 @@
#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 */
--- a/arch/riscv/lib/tishift.S
+++ b/arch/riscv/lib/tishift.S
@@ -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
+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
-ENDPROC(__lshrti3)
+SYM_FUNC_END(__ashlti3)
+EXPORT_SYMBOL(__ashlti3)