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libc/arm64: work arround linker bug for cas()

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at the _cas0 label, the linker would generate spurious stack
adjustment before the return:

atexitdont+0x84 0x000000000003614c	CLREX	$0xf
atexitdont+0x88 0x0000000000036150	MOVW	R31,R0
atexitdont+0x8c 0x0000000000036154	MOV	(SP)16!,R30 <- ????????????
atexitdont+0x90 0x0000000000036158	RETURN

the work arround is to move the code into its own cas0
text symbol.

this fixes impossible cwfs crashes in srvi().
This commit is contained in:
cinap_lenrek 2020-05-17 23:46:09 +02:00
parent b599dc0e54
commit 0002fd0cf7
2 changed files with 7 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

10
sys/src/libc/arm64/atom.s
View file

@ -3,6 +3,12 @@
* int cas(uint *p, int ov, int nv); * int cas(uint *p, int ov, int nv);
* int casl(ulong *p, ulong ov, ulong nv); * int casl(ulong *p, ulong ov, ulong nv);
*/ */
TEXT cas0(SB), 1, $-4
_cas0:
CLREX
MOVW $0, R0
RETURN
TEXT cas32(SB), 1, $-4 TEXT cas32(SB), 1, $-4
TEXT cas(SB), 1, $-4 TEXT cas(SB), 1, $-4
TEXT casl(SB), 1, $-4 TEXT casl(SB), 1, $-4
@ -16,10 +22,6 @@ _cas1:
CBNZ R4, _cas1 CBNZ R4, _cas1
MOVW $1, R0 MOVW $1, R0
B _barrier(SB) B _barrier(SB)
_cas0:
CLREX
MOVW $0, R0
RETURN
TEXT casp(SB), 1, $-4 TEXT casp(SB), 1, $-4
MOV ov+8(FP), R1 MOV ov+8(FP), R1

1
sys/src/libc/arm64/tas.s
View file

@ -5,6 +5,7 @@ _tas1:
STXRW R2, (R0), R3 STXRW R2, (R0), R3
CBNZ R3, _tas1 CBNZ R3, _tas1
MOVW R1, R0 MOVW R1, R0
B _barrier(SB)
TEXT _barrier(SB), 1, $-4 TEXT _barrier(SB), 1, $-4
DMB $0xB // ISH DMB $0xB // ISH