Date: Sat, 30 Apr 2016 15:12:26 -0500 From: Dan Parrot <dan.parrot@...l.com> To: musl@...ts.openwall.com Subject: Re: PowerPC Port: Question about magic numbers in sigsetjmp.s Thanks for the quick response. I'll take a look at the patch and comments. Dan. -----Original Message-----From: Bobby Bingham <koorogi@...rogi.info> Reply-to: musl@...ts.openwall.com To: musl@...ts.openwall.com Subject: Re: [musl] PowerPC Port: Question about magic numbers in sigsetjmp.s Date: Sat, 30 Apr 2016 14:20:48 -0500 On Sat, Apr 30, 2016 at 12:55:19PM -0500, Dan Parrot wrote: > I'm trying to modify the PowerPC port in order to run it on a 64-bit > Little Endian system. I haven't been able to get pthreads to pass the I've already submitted a patch to the mailing list to add a ppc64le port. http://www.openwall.com/lists/musl/2016/03/27/8 I'm about to submit a new version to address the remaining comments that have been made on it, but it should be close to done. > tests in libc-testsuite and I believe the culprit to be sigsetjmp.s. > > I would be grateful for an explanation of the offsets added to register > 3 in these two lines in sigsetjmp.s: > > stw 5, 448(3) > stw 16, 448+4+8(3) > See this commit: http://git.musl-libc.org/cgit/musl/commit/?id=583e55122e767b1586286a0d9c35e2a4027998ab The sigjmp_buf structure includes a __jmp_buf at the beginning (see the definition in include/setjmp.h). __jmp_buf is 448 bytes large on ppc32 (it should be larger on ppc64). So, these are accessing the part of the sigjmp_buf beyond the initial __jmp_buf. The first line is saving the return address to the __fl member, and the second line is saving r16 to __ss. The first two elements of __ss are used by __sigsetjmp_tail to save the signal mask. The remainder of __ss is unused, so it's a convenient place to spill a register to. > > Thanks. > Dan. > > Bobby
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