`zig libc` crashes with out of memory error on loongarch64

[yxd-ym]

Zig Version

0.14.0-dev.1622+2ac543388

Steps to Reproduce and Observed Behavior

1. Bootstrap a loongarch64 linux zig with ziglang/zig-bootstrap@1ad232c , either musl or gnu.
2. Run zig libc on a loongarch64 linux machine with the bootstrapped zig
3. The error occurs like this:

$ ~/opt/zig/musl/zig libc
error: OutOfMemory

Expected Behavior

zig libc returns correct libc related information on loongarch64 like x86_64 or aarch64 ones

[yxd-ym]

also see: ziglang/zig-bootstrap#164 (comment)

[alexrp]

Does it happen under QEMU?

[yxd-ym]

I bootstrapped another version with ReleaseSafe mode and the error is different

 $ ~/opt/zig/musl/zig libc
thread 59547 panic: incorrect alignment
Aborted (core dumped)

Here is the backtrace output.

(gdb) r libc
Starting program: /home/yxd/opt/zig/musl/zig libc
[New LWP 59504]
[New LWP 59505]
[New LWP 59506]
[New LWP 59507]
[New LWP 59508]
thread 59502 panic: incorrect alignment

Thread 1 "zig" received signal SIGABRT, Aborted.
raise (sig=<optimized out>) at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/libc/musl/src/signal/raise.c:12
warning: 12     /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/libc/musl/src/signal/raise.c: No such file or directory
(gdb) bt
#0  raise (sig=<optimized out>) at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/libc/musl/src/signal/raise.c:12
#1  0x000000000a8dc530 in abort () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/libc/musl/src/exit/abort.c:11
#2  0x0000000009e04490 in posix.abort () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/posix.zig:706
#3  0x000000000a840068 in debug.panicImpl (trace=0x0, first_trace_addr=...) at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/io/Writer.zig:19
#4  0x00000000099fef58 in builtin.default_panic (error_return_trace=0x0, ret_addr=...) at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/builtin.zig:885
#5  0x0000000009c247c4 in posix.mmap (ptr=<optimized out>, length=528, prot=<optimized out>, flags=<optimized out>, fd=<optimized out>, offset=0)
    at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/posix.zig:4706
#6  0x0000000009bc1a58 in crypto.tlcsprng.tlsCsprngFill () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/crypto/tlcsprng.zig:64
#7  0x0000000009c89488 in Random.bytes () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/Random.zig:55
#8  Random.int__anon_48074 () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/Random.zig:109
#9  Compilation.update (comp=0x7ffff7f9d350, main_progress_node=...) at Compilation.zig:2122
#10 0x0000000009c8fc14 in main.updateModule (comp=0x7ffff7f9d350, color=auto, prog_node=...) at main.zig:4499
#11 0x0000000009a2af0c in main.jitCmd (gpa=..., arena=..., options=...) at main.zig:5586
#12 0x00000000099feb7c in main.mainArgs (arena=...) at main.zig:303
#13 main.main () at main.zig:199
#14 start.callMain () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/start.zig:619
#15 start.callMainWithArgs () at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/start.zig:579
#16 start.main (c_argc=<optimized out>, c_argv=<optimized out>, c_envp=<optimized out>) at /Users/yxd/playspace/zig-bootstrap/out/host/lib/zig/std/start.zig:594

---

update

I got the reason of this problem, my loongarch64 machine's memory page size is not 16KiB but 4KiB.

yxd@derp ~/tmp/test_zig $ getconf PAGESIZE
4096

I will check this with linux distribution's packagers.

[yxd-ym]

Does it happen under QEMU?

I haven't try it on qemu. I will check the page size thing first.

(The two errors happen on two different machines (with same linux distribution (loongarchlinux)) with different zig optimize values (ReleaseFast vs. ReleaseSafe (no strip)))

[alexrp]

Ok, seems like this would be addressed by #20511.

[yxd-ym]

Ok, seems like this would be addressed by #20511.

OK, I will wait for this PR merged and check again.

---

However, I bootstrapped a 4KiB page size version of loongarch64-linux-musl zig for my 4KiB page size loongarchlinux machine.

For this version, zig libc works, but only with ZIG_DEBUG_CMD=1 set.

yxd@derp ~/tmp/test_zig $ ZIG_DEBUG_CMD=1 ~/opt/zig/musl/zig libc
# The directory that contains `stdlib.h`.
# On POSIX-like systems, include directories be found with: `cc -E -Wp,-v -xc /dev/null`
include_dir=/usr/include

# The system-specific include directory. May be the same as `include_dir`.
# On Windows it's the directory that includes `vcruntime.h`.
# On POSIX it's the directory that includes `sys/errno.h`.
sys_include_dir=/usr/include

# The directory that contains `crt1.o` or `crt2.o`.
# On POSIX, can be found with `cc -print-file-name=crt1.o`.
# Not needed when targeting MacOS.
crt_dir=/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.1.1/../../..

# The directory that contains `vcruntime.lib`.
# Only needed when targeting MSVC on Windows.
msvc_lib_dir=

# The directory that contains `kernel32.lib`.
# Only needed when targeting MSVC on Windows.
kernel32_lib_dir=

# The directory that contains `crtbeginS.o` and `crtendS.o`
# Only needed when targeting Haiku.
gcc_dir=

It will crash if this environment variable is not set.

yxd@derp ~/tmp/test_zig $ ~/opt/zig/musl/zig libc
Segmentation fault (core dumped)

I checked the code here

https://github.com/ziglang/zig-bootstrap/blob/9b6a22d685f78799eeb69487161df82b6c943116/zig/src/main.zig#L5452-L5455

So it seems that running jitCmd with ReleaseFast for loongarch might cause some error.

[yxd-ym]

Backtrace of

yxd@derp ~/tmp/test_zig $ ~/opt/zig/musl/zig libc
Segmentation fault (core dumped)

is like this after I disabled strip in jitCmd function for ReleaseFast.

(gdb) r libc
Starting program: /home/yxd/.cache/zig/o/524096a6eb1b49fde3b21dc390171077/libc libc

Program received signal SIGSEGV, Segmentation fault.
0x0000000001083b6c in posix.openatZ (dir_fd=<optimized out>, file_path=0x7ffffffef9b8 "/usr/bin/env", flags=<optimized out>, mode=0)
    at /home/yxd/opt/zig/musl-debug/lib/std/posix.zig:1775
1775            switch (errno(rc)) {
(gdb) bt
#0  0x0000000001083b6c in posix.openatZ (dir_fd=<optimized out>, file_path=0x7ffffffef9b8 "/usr/bin/env", flags=<optimized out>, mode=0)
    at /home/yxd/opt/zig/musl-debug/lib/std/posix.zig:1775
#1  0x00000000010753c0 in fs.Dir.openFileZ (sub_path=0x7ffffffef9b8 "/usr/bin/env", flags=...) at /home/yxd/opt/zig/musl-debug/lib/std/fs/Dir.zig:882
#2  fs.Dir.openFile (flags=...) at /home/yxd/opt/zig/musl-debug/lib/std/fs/Dir.zig:829
#3  0x000000000107c93c in fs.openFileAbsolute () at /home/yxd/opt/zig/musl-debug/lib/std/fs.zig:280
#4  zig.system.detectAbiAndDynamicLinker (os=..., query=...) at /home/yxd/opt/zig/musl-debug/lib/std/zig/system.zig:1037
#5  zig.system.resolveTargetQuery (query=...) at /home/yxd/opt/zig/musl-debug/lib/std/zig/system.zig:348
#6  zig.resolveTargetQueryOrFatal (target_query=...) at /home/yxd/opt/zig/musl-debug/lib/std/zig.zig:613
#7  libc.main () at libc.zig:66
#8  0x00000000010752a4 in start.callMain () at /home/yxd/opt/zig/musl-debug/lib/std/start.zig:619
#9  start.callMainWithArgs () at /home/yxd/opt/zig/musl-debug/lib/std/start.zig:579
#10 start.posixCallMainAndExit (argc_argv_ptr=<optimized out>) at /home/yxd/opt/zig/musl-debug/lib/std/start.zig:535
#11 0x0000000000000000 in ?? ()
Backtrace stopped: frame did not save the PC

and in frame 0, rc = 4

[alexrp]

Does this still happen on master?

[yxd-ym]

I used the latest version downloaded from https://ziglang.org/download/ . It still happens.

$ zig version
0.15.0-dev.345+ec2888858
$ zig libc
error: OutOfMemory
Segmentation fault (core dumped)

However, running with ZIG_DEBUG_CMD=1 also still works.

$ ZIG_DEBUG_CMD=1 zig libc
# The directory that contains `stdlib.h`.
# On POSIX-like systems, include directories be found with: `cc -E -Wp,-v -xc /dev/null`
include_dir=/usr/include

# The system-specific include directory. May be the same as `include_dir`.
# On Windows it's the directory that includes `vcruntime.h`.
# On POSIX it's the directory that includes `sys/errno.h`.
sys_include_dir=/usr/include

# The directory that contains `crt1.o` or `crt2.o`.
# On POSIX, can be found with `cc -print-file-name=crt1.o`.
# Not needed when targeting MacOS.
crt_dir=/usr/lib/gcc/loongarch64-unknown-linux-gnu/14.2.1/../../..

# The directory that contains `vcruntime.lib`.
# Only needed when targeting MSVC on Windows.
msvc_lib_dir=

# The directory that contains `kernel32.lib`.
# Only needed when targeting MSVC on Windows.
kernel32_lib_dir=

# The directory that contains `crtbeginS.o` and `crtendS.o`
# Only needed when targeting Haiku.
gcc_dir=