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Message-ID: <5fe467cd-4b68-2841-8aae-c485e7570267@loongson.cn>
Date: Sat, 21 May 2022 14:38:20 +0800
From: 王洪亮 <wanghongliang@...ngson.cn>
To: musl@...ts.openwall.com
Subject: Re: add loongarch64 port v3


在 2022/5/16 下午10:27, Rich Felker 写道:
> OK, review follows:
>> diff --git a/arch/loongarch64/bits/signal.h b/arch/loongarch64/bits/signal.h
>> new file mode 100644
>> index 00000000..e6613516
>> --- /dev/null
>> +++ b/arch/loongarch64/bits/signal.h
>> @@ -0,0 +1,79 @@
>> +#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
>> + || defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
>> +
>> +#if defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
>> +#define MINSIGSTKSZ 4096
>> +#define SIGSTKSZ 16384
>> +#endif
>> +
>> +typedef unsigned long greg_t, gregset_t[32];
>> +
>> +typedef struct sigcontext {
>> +	unsigned long pc;
>> +	gregset_t gregs;
>> +	unsigned int flags;
>> +	unsigned long extcontext[0] __attribute__((__aligned__(16)));
>> +}mcontext_t;
> Again, [0] is not valid C. If the extension field is going to be
> declared at all it needs to be declared in a way it can be accessed
> without invoking UB, e.g. as a FAM.

[0] is allowed in GNU C, we can not use it in musl ?

I don't understand  UB ?  e.g. as a FAM ?

> I'm also not clear on how
> specifying the alignment here helps since any object created in a way
> that the alignment would affect cannot have the FAM present.
>
the __aligned__(16)  here used to save 128bit vector later.
>
>> diff --git a/arch/loongarch64/kstat.h b/arch/loongarch64/kstat.h
>> new file mode 100644
>> index 00000000..900f119d
>> --- /dev/null
>> +++ b/arch/loongarch64/kstat.h
>> @@ -0,0 +1,21 @@
>> +struct kstat {
>> +	dev_t st_dev;
>> +	ino_t st_ino;
>> +	mode_t st_mode;
>> +	nlink_t st_nlink;
>> +	uid_t st_uid;
>> +	gid_t st_gid;
>> +	dev_t st_rdev;
>> +	unsigned long __pad;
>> +	off_t st_size;
>> +	blksize_t st_blksize;
>> +	int __pad2;
>> +	blkcnt_t st_blocks;
>> +	long st_atime_sec;
>> +	unsigned long st_atime_nsec;
>> +	long st_mtime_sec;
>> +	unsigned long st_mtime_nsec;
>> +	long st_ctime_sec;
>> +	unsigned long st_ctime_nsec;
>> +	unsigned __unused[2];
>> +};
> I think this file should be removed, right? -- since there is no
> legacy stat sycall with a kstat structure.
yes, I removed this file.
>> diff --git a/arch/loongarch64/reloc.h b/arch/loongarch64/reloc.h
>> new file mode 100644
>> index 00000000..249cb40c
>> --- /dev/null
>> +++ b/arch/loongarch64/reloc.h
>> @@ -0,0 +1,35 @@
>> +#ifndef __RELOC_H__
>> +#define __RELOC_H__
>> +
>> +#define _GNU_SOURCE
>> +#include <endian.h>
> You cannot define FTMs in the middle of a header file that might be
> included somewhere other than the very top of a source file. But there
> does not seem to be any reason it's defined at all.

I fixed this error:

diff --git a/arch/loongarch64/reloc.h b/arch/loongarch64/reloc.h

index 249cb40c..2f759a34 100644
--- a/arch/loongarch64/reloc.h
+++ b/arch/loongarch64/reloc.h
@@ -1,9 +1,3 @@
-#ifndef __RELOC_H__
-#define __RELOC_H__
-
-#define _GNU_SOURCE
-#include <endian.h>
-
  #ifdef __loongarch64_soft_float
  #define FP_SUFFIX "-sf"
  #else
@@ -31,5 +25,3 @@
      "    la.local $t1, "#sym" \n" \
      "    or %0, $t1, $zero \n" \
      : "=r"(*(fp)) : : "memory" )
-
-#endif

>> diff --git a/src/ldso/loongarch64/dlsym.s b/src/ldso/loongarch64/dlsym.s
>> new file mode 100644
>> index 00000000..10ac5c7f
>> --- /dev/null
>> +++ b/src/ldso/loongarch64/dlsym.s
>> @@ -0,0 +1,12 @@
>> +.global dlsym
>> +.hidden __dlsym
>> +.type   dlsym,@function
>> +dlsym:
>> +	move	$a2, $ra
>> +	la.global	$r16, __dlsym
>> +	addi.d 	$sp, $sp, -8
>> +	st.d	$ra, $sp, 0
>> +	jirl	$ra, $r16, 0
>> +	ld.d	$ra, $sp, 0
>> +	addi.d	$sp, $sp, 8
>> +	jirl	$r0, $ra, 0
> Is there a reason this can't be a tail call? Maybe the ABI requires
> that the caller reserve space for the callee to spill arg registers
> that are used?

I optimized the code implementation:

diff --git a/src/ldso/loongarch64/dlsym.s b/src/ldso/loongarch64/dlsym.s
index 10ac5c7f..5f51ed85 100644
--- a/src/ldso/loongarch64/dlsym.s
+++ b/src/ldso/loongarch64/dlsym.s
@@ -4,9 +4,4 @@
  dlsym:
      move    $a2, $ra
      la.global    $r16, __dlsym
-    addi.d     $sp, $sp, -8
-    st.d    $ra, $sp, 0
-    jirl    $ra, $r16, 0
-    ld.d    $ra, $sp, 0
-    addi.d    $sp, $sp, 8
-    jirl    $r0, $ra, 0
+    jirl    $r0, $r16, 0
-- 

>> diff --git a/src/thread/loongarch64/clone.s b/src/thread/loongarch64/clone.s
>> new file mode 100644
>> index 00000000..ec920c7b
>> --- /dev/null
>> +++ b/src/thread/loongarch64/clone.s
>> @@ -0,0 +1,47 @@
>> +#__clone(func, stack, flags, arg, ptid, tls, ctid)
>> +#         a0,    a1,   a2,    a3,  a4,  a5,   a6
>> +# sys_clone3(struct clone_args *cl_args, size_t size)
>> +#                                 a0             a1
>> +
>> +.global	__clone
>> +.hidden __clone
>> +.type	__clone,@function
>> +__clone:
>> +	# Save function pointer and argument pointer on new thread stack
>> +	addi.d	$a1, $a1, -16
>> +	st.d	$a0, $a1, 0	# save function pointer
>> +	st.d	$a3, $a1, 8	# save argument pointer
>> +
>> +	li.d	$t0, ~0x004000ff  # mask CSIGNAL and CLONE_DETACHED
>> +	and	$t1, $a2, $t0     # cl_args.flags
>> +	li.d	$t0, 0x000000ff   # CSIGNAL
>> +	and	$t2, $a2, $t0     # cl_args.exit_signal
>> +
>> +	bstrins.d $sp, $zero, 2, 0  # align stack to 8 bytes
>> +	addi.d	$sp, $sp, -88   # struct clone_args
>> +	st.d	$t1, $sp, 0     # flags
>> +	st.d	$a4, $sp, 8     # pidfd
>> +	st.d	$a6, $sp, 16    # child_tid
>> +	st.d	$a4, $sp, 24    # parent_tid
>> +	st.d	$t2, $sp, 32    # exit_signal
>> +	st.d	$a1, $sp, 40    # stack
>> +	st.d	$zero, $sp, 48  # stack_size
>> +	st.d	$a5, $sp, 56    # tls
>> +	st.d	$zero, $sp, 64  # set_tid
>> +	st.d	$zero, $sp, 72  # set_tid_size
>> +	st.d	$zero, $sp, 80  # cgroup
>> +
>> +	move	$a0, $sp
>> +	li.d	$a1, 88
>> +	li.d	$a7, 435	# __NR_clone3
>> +	syscall 0		# call clone3
>> +
>> +	beqz	$a0, 1f		# whether child process
>> +	addi.d	$sp, $sp, 88
>> +	jirl	$zero, $ra, 0	# parent process return
>> +1:
>> +	ld.d	$t8, $sp, 0     # function pointer
>> +	ld.d	$a0, $sp, 8     # argument pointer
>> +	jirl	$ra, $t8, 0     # call the user's function
>> +	li.d	$a7, 93
>> +	syscall	0		# child process exit
> Based on the outcome of the kernel discussiong about __NR_clone3 vs
> __NR_clone, this likely needs to be reverted to use __NR_clone again.
> I'm waiting to see how that comes out. Sorry for the back and forth
> while we try to get this right on the kernel side.
OK,No problem.

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