On Tue, Feb 2, 2016 at 10:13 AM, Konstantin Belousov <k...@freebsd.org> wrote: > On Tue, Feb 02, 2016 at 10:05:16AM -0600, Justin Hibbits wrote: >> Good catch! I'll commit the change tonight. > I looked once at the powerpc sigsend(), and I think that it has an > issue. The usfp is calculated by taking the stack pointer at the time > of signal delivery and substracting the sigframe size. This means that > a transient misalignment during some code (e.g. leaf function) is > transferred to the signal handler execution. > > Other arches explicitely realign stack pointer for the signal > frame before the frame is formed. > > I am not sure if the problem reported in the thread is caused by this > or not, but forced realignment in sendsig() is required for ABI compliance.
Good point. Currently the assumption is that the stack will always be 16-byte aligned, which is required per ABI. Since there's no push/pop, only full frame creation/destruction, it hasn't bitten us yet, but it should be fixed. It's not the cause of this bug, though. This bug is caused after sendsig(), in the sigcode trampoline in user space. - Justin _______________________________________________ freebsd-toolchain@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-toolchain To unsubscribe, send any mail to "freebsd-toolchain-unsubscr...@freebsd.org"
