Date: Sun, 31 Jan 2016 18:42:25 -0600 From: Justin Hibbits <chmeeedalf@gmail.com> To: Mark Millard <markmi@dsl-only.net> Cc: freebsd-toolchain@freebsd.org, Nathan Whitehorn <nwhitehorn@freebsd.org>, Roman Divacky <rdivacky@vlakno.cz>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org> Subject: Re: 3 quick questions about stack alignment for powerpc (32-bit) signal handlers Message-ID: <CAHSQbTCCM9RVe=maoSbSXb6MzqJK%2BBQWgOkWWvn5wbaw13JBqg@mail.gmail.com> In-Reply-To: <0716BE3E-B7D1-4A10-B011-C1F0245296E7@dsl-only.net> References: <517B7923-5166-42D0-8FA8-52C05F956F06@dsl-only.net> <20160131140807.GA83147@vlakno.cz> <0716BE3E-B7D1-4A10-B011-C1F0245296E7@dsl-only.net>
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I'll take a look at the signal code in the kernel this evening. -Justin On Jan 31, 2016 18:41, "Mark Millard" <markmi@dsl-only.net> wrote: > I have submitted Bug 206810 for this 11.0-CURRENT/clang380-import stack > alignment problem for TARGET_ARCH=powerpc signal delivery. > > === > Mark Millard > markmi at dsl-only.net > > On 2016-Jan-31, at 6:08 AM, Roman Divacky <rdivacky at vlakno.cz> wrote: > > Fwiw, LLVM expect 16B aligned stack on PowerPC. > > On Sun, Jan 31, 2016 at 05:55:20AM -0800, Mark Millard wrote: > > 3 quick FreeBSD for powerpc (32-bit) questions: > > > > > > A) For PowerPC (32-bit) what is the stack alignment requirement by the > ABI(s) that FreeBSD targets? > > > > B) Are signal handlers supposed to be given that alignment? > > > > > > I ask because signal handlers are at times begin given just 4-byte > alignment but clang 3.8.0 powerpc's code generation can depend on the > alignment being more than 4. > > > > clang 3.8.0 can calculate addresses by, for example, masking in a 0x4 > relative to what would need to be an aligned address with alignment 8 or > more instead of adding 0x4 to a more arbitrary address. > > > > So far I've only seen less than 8 byte stack alignment via signal > handler activity. > > > > > > C) Which should be blamed for problems here: clang's code generation, > FreeBSD's stack alignment handling for signals, or both? > > > > === > > Mark Millard > > markmi at dsl-only.net > > > > _______________________________________________ > > freebsd-toolchain@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain > > To unsubscribe, send any mail to " > freebsd-toolchain-unsubscribe@freebsd.org" > >
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