* [musl] C++ segfault on riscv64
@ 2022-03-18 16:41 Kenny, Joseph P
2022-03-18 16:48 ` [musl] Re: [EXTERNAL] " Kenny, Joseph P
0 siblings, 1 reply; 3+ messages in thread
From: Kenny, Joseph P @ 2022-03-18 16:41 UTC (permalink / raw)
To: musl
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I’m getting segfaults with musl for C++ code on riscv64. I have tested mipsel using qemu user mode as described below and found no issues.
I’m cross-compiling using the latest riscv64-linux-musl-cross.tgz (23-Nov-2021) from musl.cc on x86_64/Fedora 35. I have confirmed that I get the following behavior for both riscv64 hardware and qemu user mode.
C is fine:
$ cat hello.c
#include<stdio.h>
int main(int argc, char **argv) {
printf("Hello\n");
return 0;
}
$ riscv32-linux-musl-gcc -static -g -Og hello.c -o hello
$ qemu-riscv32 hello
Hello
C++ segfaults:
$ riscv32-linux-musl-g++ -static -g -Og hello.cc -o hello
$ qemu-riscv32 hello
Segmentation fault (core dumped)
GDB confirms the segfault in __dynamic_cast on both qmeu and riscv64 hardware. I’ll paste in the assembly below. Segfault occurs on the last instruction shown [ld a5,0(a0)].
I’ve taken this as far as my skills allow. Any ideas what’s going on here or how to debug further?
Thanks
000000000007d38e <__dynamic_cast>:
7d38e: c55d beqz a0,7d43c <__dynamic_cast+0xae>
7d390: 00053803 ld a6,0(a0)
7d394: 715d addi sp,sp,-80
7d396: fc26 sd s1,56(sp)
7d398: ff083703 ld a4,-16(a6)
7d39c: ff883783 ld a5,-8(a6)
7d3a0: 84b6 mv s1,a3
7d3a2: 972a add a4,a4,a0
7d3a4: 6314 ld a3,0(a4)
7d3a6: 4805 li a6,1
7d3a8: 1812 slli a6,a6,0x24
7d3aa: e802 sd zero,16(sp)
7d3ac: ec42 sd a6,24(sp)
7d3ae: e0a2 sd s0,64(sp)
7d3b0: 842a mv s0,a0
7d3b2: ff86b503 ld a0,-8(a3)
7d3b6: e486 sd ra,72(sp)
7d3b8: f84a sd s2,48(sp)
7d3ba: f44e sd s3,40(sp)
7d3bc: f052 sd s4,32(sp)
7d3be: e402 sd zero,8(sp)
7d3c0: 04f51663 bne a0,a5,7d40c <__dynamic_cast+0x7e>
7d3c4: 611c ld a5,0(a0)
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^ permalink raw reply [flat|nested] 3+ messages in thread
* [musl] Re: [EXTERNAL] [musl] C++ segfault on riscv64
2022-03-18 16:41 [musl] C++ segfault on riscv64 Kenny, Joseph P
@ 2022-03-18 16:48 ` Kenny, Joseph P
2022-03-19 8:44 ` Szabolcs Nagy
0 siblings, 1 reply; 3+ messages in thread
From: Kenny, Joseph P @ 2022-03-18 16:48 UTC (permalink / raw)
To: musl
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Sorry for the confusing post. I get the same behavior on qemu for both riscv64 and riscv32. I posted output from riscv32.
Here is the C++ code:
$ cat hello.cc
#include <iostream>
int main() {
std::cout << "Hello\n";
return 0;
}
From: "Kenny, Joseph P" <jpkenny@sandia.gov>
Reply-To: "musl@lists.openwall.com" <musl@lists.openwall.com>
Date: Friday, March 18, 2022 at 9:42 AM
To: "musl@lists.openwall.com" <musl@lists.openwall.com>
Subject: [EXTERNAL] [musl] C++ segfault on riscv64
I’m getting segfaults with musl for C++ code on riscv64. I have tested mipsel using qemu user mode as described below and found no issues.
I’m cross-compiling using the latest riscv64-linux-musl-cross.tgz (23-Nov-2021) from musl.cc on x86_64/Fedora 35. I have confirmed that I get the following behavior for both riscv64 hardware and qemu user mode.
C is fine:
$ cat hello.c
#include<stdio.h>
int main(int argc, char **argv) {
printf("Hello\n");
return 0;
}
$ riscv32-linux-musl-gcc -static -g -Og hello.c -o hello
$ qemu-riscv32 hello
Hello
C++ segfaults:
$ riscv32-linux-musl-g++ -static -g -Og hello.cc -o hello
$ qemu-riscv32 hello
Segmentation fault (core dumped)
GDB confirms the segfault in __dynamic_cast on both qmeu and riscv64 hardware. I’ll paste in the assembly below. Segfault occurs on the last instruction shown [ld a5,0(a0)].
I’ve taken this as far as my skills allow. Any ideas what’s going on here or how to debug further?
Thanks
000000000007d38e <__dynamic_cast>:
7d38e: c55d beqz a0,7d43c <__dynamic_cast+0xae>
7d390: 00053803 ld a6,0(a0)
7d394: 715d addi sp,sp,-80
7d396: fc26 sd s1,56(sp)
7d398: ff083703 ld a4,-16(a6)
7d39c: ff883783 ld a5,-8(a6)
7d3a0: 84b6 mv s1,a3
7d3a2: 972a add a4,a4,a0
7d3a4: 6314 ld a3,0(a4)
7d3a6: 4805 li a6,1
7d3a8: 1812 slli a6,a6,0x24
7d3aa: e802 sd zero,16(sp)
7d3ac: ec42 sd a6,24(sp)
7d3ae: e0a2 sd s0,64(sp)
7d3b0: 842a mv s0,a0
7d3b2: ff86b503 ld a0,-8(a3)
7d3b6: e486 sd ra,72(sp)
7d3b8: f84a sd s2,48(sp)
7d3ba: f44e sd s3,40(sp)
7d3bc: f052 sd s4,32(sp)
7d3be: e402 sd zero,8(sp)
7d3c0: 04f51663 bne a0,a5,7d40c <__dynamic_cast+0x7e>
7d3c4: 611c ld a5,0(a0)
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [musl] Re: [EXTERNAL] [musl] C++ segfault on riscv64
2022-03-18 16:48 ` [musl] Re: [EXTERNAL] " Kenny, Joseph P
@ 2022-03-19 8:44 ` Szabolcs Nagy
0 siblings, 0 replies; 3+ messages in thread
From: Szabolcs Nagy @ 2022-03-19 8:44 UTC (permalink / raw)
To: Kenny, Joseph P; +Cc: musl
* Kenny, Joseph P <jpkenny@sandia.gov> [2022-03-18 16:48:11 +0000]:
> Sorry for the confusing post. I get the same behavior on qemu for both riscv64 and riscv32. I posted output from riscv32.
>
> Here is the C++ code:
> $ cat hello.cc
> #include <iostream>
> int main() {
> std::cout << "Hello\n";
> return 0;
> }
>
> From: "Kenny, Joseph P" <jpkenny@sandia.gov>
> Reply-To: "musl@lists.openwall.com" <musl@lists.openwall.com>
> Date: Friday, March 18, 2022 at 9:42 AM
> To: "musl@lists.openwall.com" <musl@lists.openwall.com>
> Subject: [EXTERNAL] [musl] C++ segfault on riscv64
>
> I’m getting segfaults with musl for C++ code on riscv64. I have tested mipsel using qemu user mode as described below and found no issues.
>
> I’m cross-compiling using the latest riscv64-linux-musl-cross.tgz (23-Nov-2021) from musl.cc on x86_64/Fedora 35. I have confirmed that I get the following behavior for both riscv64 hardware and qemu user mode.
...
> C++ segfaults:
>
> $ riscv32-linux-musl-g++ -static -g -Og hello.cc -o hello
> $ qemu-riscv32 hello
> Segmentation fault (core dumped)
>
> GDB confirms the segfault in __dynamic_cast on both qmeu and riscv64 hardware. I’ll paste in the assembly below. Segfault occurs on the last instruction shown [ld a5,0(a0)].
>
> I’ve taken this as far as my skills allow. Any ideas what’s going on here or how to debug further?
listdc++ iostreams initializers call __dynamic_cast many times (this is
all in libstdc++, nothing to do with musl).
you need to figure out which cast fails and why the type info is corrupt.
e.g. build libstdc++ with debug info and printing the backtrace may help.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-03-18 16:41 [musl] C++ segfault on riscv64 Kenny, Joseph P
2022-03-18 16:48 ` [musl] Re: [EXTERNAL] " Kenny, Joseph P
2022-03-19 8:44 ` Szabolcs Nagy
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