[PATCH] sh: Fix args for __uClibc_main() in crt1.S
Carmelo AMOROSO
carmelo.amoroso at st.com
Wed Aug 6 12:42:46 UTC 2008
Carmelo AMOROSO wrote:
> Takashi Yoshii wrote:
>> Hi,
>>
>> As a comment in libc/sysdeps/linux/sh/crt1.S says
>>> /* __uClibc_main (main, argc, argv, init, fini) */
>> , something wrong here. There should be two more args.
>>
>> 7th arg "stack_end" seems to be missing.
>> 6th one is not listed, but the original code pushed register "r4" here.
>> It is not documented, but because ldso/ldso/sh/dl-startup.h explicitly sets
>> 0 to r4 just before jump here, there must be a kind of calling convention.
>> So, I preserve the code, and add a comment that this is the way to pass
>> rtld_fini from prior routine.
>> I really can't find any documents about this convention, though.
>>
>> /yoshii
>>
>> ---
>> sh: Fix args for __uClibc_main() in crt1.S
>> add missing 7th arg "stack_end".
>> add comment of undocumented usage of r4.
>> fix comment of expected __uClibc_main() prototype.
>>
>> diff --git a/libc/sysdeps/linux/sh/crt1.S b/libc/sysdeps/linux/sh/crt1.S
>> --- a/libc/sysdeps/linux/sh/crt1.S
>> +++ b/libc/sysdeps/linux/sh/crt1.S
>> @@ -24,6 +24,11 @@
>>
>> At this entry point, most registers' values are unspecified, except:
>>
>> + r4 Contains a function pointer to be registered with `atexit'.
>> + This is how the dynamic linker arranges to have DT_FINI
>> + functions called for shared libraries that have been loaded
>> + before this code runs.
>> +
>> sp The stack contains the arguments and environment:
>> 0(sp) argc
>> 4(sp) argv[0]
>> @@ -48,7 +53,8 @@ _start:
>> mov.l @r15+,r5
>> mov r15, r6
>>
>> - /* Push the fini func onto the stack */
>> + /* Push the stack_end, rtld_fini and fini func onto the stack */
>> + mov.l r6, at -r15
>> mov.l r4, at -r15
>> mov.l L_fini,r0
>> mov.l r0, at -r15
>> @@ -57,7 +63,7 @@ _start:
>> mov.l L_main,r4
>> mov.l L_init,r7
>>
>> - /* __uClibc_main (main, argc, argv, init, fini) */
>> + /* __uClibc_main (main, argc, argv, init, fini, rtld_fini, stack_end) */
>>
>> /* Let the libc call main and exit with its return code. */
>> mov.l L_uClibc_main,r1
>>
>
> Hi Takashi,
> your point is correct and the patch looks fine. Looking again at the
> ld.so -> _start flow, yes sh4 forces rtld_fini to be NULL (r4 = 0 set in
> dl-startup.h as you told), so this means that on sh4 we do not call the
> _dl_fini destructor, loosing eventually to call the destructors of the
> dependant shared objects.
> It should be simple enough to write a test showing this.
Well, I've written the test and, as I thought, we do not call the
destructor for any dependant shared objects.
> I'll spend a few time longer to look at what it's happening on glibc
> part, and eventually integrate your patch by setting the rtld_fini (6 ^
> args) too.
>
Indeed glibc (sysdeps/sh/dl-machine.h: _start) passes in r4 the _dl_fini
instead of NULL. This makes dso's destructor get properly called.
I'll see how to integrate a test case into the test-suite too.
Full fix will come soon.
Carmelo
> Thanks a lot,
> Carmelo
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