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Date: Thu, 14 Mar 2024 14:45:29 +0800
From: lixing <lixing@...ngson.cn>
To: musl@...ts.openwall.com
Subject: Re: loongarch64 atomics not working?
在 2024/3/14 下午1:44, Waldemar Brodkorb 写道:
> Hi,
> Rich Felker wrote,
>
>>> Yes I do. I found the reason why my mksh didn't worked.
>>> I compiled everything with -Os and then I get the deadlock.
>>> When I compile everything with -O2 musl mksh is working.
>>>
>>> So it seems some gcc problem code compiled with -Os.
>> Let's look at the generated asm for the function using a_cas_p and see
>> if this is a gcc bug or if the asm argument constraints as written
>> allowed a transformation that's not actually valid.
> Broken mksh with -Os:
>
> 000000012003b970 <cgt_init>:
> 12003b970: 02ff8063 addi.d $sp, $sp, -32
> 12003b974: 29c02077 st.d $s0, $sp, 8
> 12003b978: 27000078 stptr.d $s1, $sp, 0
> 12003b97c: 00150097 move $s0, $a0
> 12003b980: 001500b8 move $s1, $a1
> 12003b984: 1a000084 pcalau12i $a0, 4
> 12003b988: 1a000085 pcalau12i $a1, 4
> 12003b98c: 29c04076 st.d $fp, $sp, 16
> 12003b990: 29c06061 st.d $ra, $sp, 24
> 12003b994: 02c08076 addi.d $fp, $sp, 32
> 12003b998: 02c060a5 addi.d $a1, $a1, 24
> 12003b99c: 02c0c084 addi.d $a0, $a0, 48
> 12003b9a0: 54021400 bl 532 # 12003bbb4 <__vdsosym>
> 12003b9a4: 0015008e move $t2, $a0
> 12003b9a8: 38720000 dbar 0x0
> 12003b9ac: 1a00002d pcalau12i $t1, 1
> 12003b9b0: 1a00032f pcalau12i $t3, 25
> 12003b9b4: 02e5c1ad addi.d $t1, $t1, -1680
> 12003b9b8: 02ca21ec addi.d $t0, $t3, 648
> 12003b9bc: 2200018c ll.d $t0, $t0, 0
> 12003b9c0: 5c00198d bne $t0, $t1, 24 # 12003b9d8 <cgt_init+0x68>
> 12003b9c4: 001501cc move $t0, $t2
> 12003b9c8: 02ca21f0 addi.d $t4, $t3, 648
> 12003b9cc: 2300020c sc.d $t0, $t4, 0
> 12003b9d0: 0040818c slli.w $t0, $t0, 0x0
> 12003b9d4: 43ffe59f beqz $t0, -28 # 12003b9b8 <cgt_init+0x48>
> 12003b9d8: 38720000 dbar 0x0
> 12003b9dc: 400025c0 beqz $t2, 36 # 12003ba00 <cgt_init+0x90>
> 12003b9e0: 28c04076 ld.d $fp, $sp, 16
> 12003b9e4: 28c06061 ld.d $ra, $sp, 24
> 12003b9e8: 00150305 move $a1, $s1
> 12003b9ec: 001502e4 move $a0, $s0
> 12003b9f0: 26000078 ldptr.d $s1, $sp, 0
> 12003b9f4: 28c02077 ld.d $s0, $sp, 8
> 12003b9f8: 02c08063 addi.d $sp, $sp, 32
> 12003b9fc: 4c0001c0 jr $t2
> 12003ba00: 28c06061 ld.d $ra, $sp, 24
> 12003ba04: 28c04076 ld.d $fp, $sp, 16
> 12003ba08: 28c02077 ld.d $s0, $sp, 8
> 12003ba0c: 26000078 ldptr.d $s1, $sp, 0
> 12003ba10: 02bf6804 li.w $a0, -38
> 12003ba14: 02c08063 addi.d $sp, $sp, 32
> 12003ba18: 4c000020 ret
>
> Working mksh with -O2:
> 0000000120045f50 <cgt_init>:
> 120045f50: 02ff8063 addi.d $sp, $sp, -32
> 120045f54: 29c02077 st.d $s0, $sp, 8
> 120045f58: 27000078 stptr.d $s1, $sp, 0
> 120045f5c: 00150097 move $s0, $a0
> 120045f60: 001500b8 move $s1, $a1
> 120045f64: 1a000084 pcalau12i $a0, 4
> 120045f68: 1a000085 pcalau12i $a1, 4
> 120045f6c: 29c04076 st.d $fp, $sp, 16
> 120045f70: 29c06061 st.d $ra, $sp, 24
> 120045f74: 02c08076 addi.d $fp, $sp, 32
> 120045f78: 02dbc0a5 addi.d $a1, $a1, 1776
> 120045f7c: 02dc2084 addi.d $a0, $a0, 1800
> 120045f80: 54024c00 bl 588 # 1200461cc <__vdsosym>
> 120045f84: 0015008f move $t3, $a0
> 120045f88: 38720000 dbar 0x0
> 120045f8c: 1a000030 pcalau12i $t4, 1
> 120045f90: 1a00036d pcalau12i $t1, 27
> 120045f94: 02fd4210 addi.d $t4, $t4, -176
> 120045f98: 50001400 b 20 # 120045fac <cgt_init+0x5c>
> 120045f9c: 02ca21ae addi.d $t2, $t1, 648
> 120045fa0: 230001cc sc.d $t0, $t2, 0
> 120045fa4: 0040818c slli.w $t0, $t0, 0x0
> 120045fa8: 44001580 bnez $t0, 20 # 120045fbc <cgt_init+0x6c>
> 120045fac: 02ca21ac addi.d $t0, $t1, 648
> 120045fb0: 2200018e ll.d $t2, $t0, 0
> 120045fb4: 001501ec move $t0, $t3
> 120045fb8: 5bffe60e beq $t4, $t2, -28 # 120045f9c <cgt_init+0x4c>
> 120045fbc: 38720000 dbar 0x0
> 120045fc0: 400025e0 beqz $t3, 36 # 120045fe4 <cgt_init+0x94>
> 120045fc4: 28c04076 ld.d $fp, $sp, 16
> 120045fc8: 28c06061 ld.d $ra, $sp, 24
> 120045fcc: 00150305 move $a1, $s1
> 120045fd0: 001502e4 move $a0, $s0
> 120045fd4: 26000078 ldptr.d $s1, $sp, 0
> 120045fd8: 28c02077 ld.d $s0, $sp, 8
> 120045fdc: 02c08063 addi.d $sp, $sp, 32
> 120045fe0: 4c0001e0 jr $t3
> 120045fe4: 28c06061 ld.d $ra, $sp, 24
> 120045fe8: 28c04076 ld.d $fp, $sp, 16
> 120045fec: 28c02077 ld.d $s0, $sp, 8
> 120045ff0: 26000078 ldptr.d $s1, $sp, 0
> 120045ff4: 02bf6804 li.w $a0, -38
> 120045ff8: 02c08063 addi.d $sp, $sp, 32
> 120045ffc: 4c000020 ret
>
> Does that help? Both binaries can be found on https://debug.openadk.org.
>
> best regards
> Waldemar
we checked the objdump binaries for -Os and -O2, the a_cas_p implement
looks ok for both.
Also, we cross build the musl and mksh with -Os, the binary hang with
qemu user mode emulation , but not hang in the real hardware.
so, maybe this is a qemu problem, we will let our qemu guys to check
this problem.
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