Date: Sun, 06 Jul 2014 12:21:49 -0700 From: Nathan Whitehorn <nwhitehorn@freebsd.org> To: Andrew Turner <andrew@freebsd.org>, src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r268310 - head/libexec/rtld-elf/arm Message-ID: <53B9A1CD.2010803@freebsd.org> In-Reply-To: <201407061024.s66AO6R9012248@svn.freebsd.org> References: <201407061024.s66AO6R9012248@svn.freebsd.org>
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Thank you! I can now upgrade my AVILA for the first time in 3 years. Most things seem to work fine, despite the long absence. -Nathan On 07/06/14 03:24, Andrew Turner wrote: > Author: andrew > Date: Sun Jul 6 10:24:06 2014 > New Revision: 268310 > URL: http://svnweb.freebsd.org/changeset/base/268310 > > Log: > Align the stack in _rtld_bind_start. Normally this is called with the > correct stack alignment, however when we have a leaf function that uses > thread local storage it calls __aeabi_read_tp to get the thread pointer. > Neither GCC or clang see this as a function call so will align the stack > to a 4-byte boundary. This may be a problem as _rtld_bind expects to be > on an 8-byte boundary. > > The solution is to store a copy of the stack pointer and force the > alignment before calling _rtld_bind. > > This fixes a problem with armeb where applications would crash in odd ways. > It should also remove the need for a local patch to clang to force the > stack alignment to an 8-byte boundary, even for leaf functions. Further > testing will be needed before reverting this local change to clang as we > may rely on it in other places. > > Reviewed by: jmg@ > > Modified: > head/libexec/rtld-elf/arm/rtld_start.S > > Modified: head/libexec/rtld-elf/arm/rtld_start.S > ============================================================================== > --- head/libexec/rtld-elf/arm/rtld_start.S Sun Jul 6 07:34:18 2014 (r268309) > +++ head/libexec/rtld-elf/arm/rtld_start.S Sun Jul 6 10:24:06 2014 (r268310) > @@ -77,7 +77,7 @@ __FBSDID("$FreeBSD$"); > * lr = &GOT[2] > */ > _rtld_bind_start: > - stmdb sp!,{r0-r4,sl,fp} > + stmdb sp!,{r0-r5,sl,fp} > > sub r1, ip, lr /* r1 = 4 * (n + 1) */ > sub r1, r1, #4 /* r1 = 4 * n */ > @@ -86,11 +86,14 @@ _rtld_bind_start: > ldr r0, [lr, #-4] /* get obj ptr from GOT[1] */ > mov r4, ip /* save GOT location */ > > + mov r5, sp /* Save the stack pointer */ > + bic sp, sp, #7 /* Align the stack pointer */ > bl _rtld_bind /* Call the binder */ > + mov sp, r5 /* Restore the old stack pointer */ > > str r0, [r4] /* save address in GOT */ > mov ip, r0 /* save new address */ > > - ldmia sp!,{r0-r4,sl,fp,lr} /* restore the stack */ > + ldmia sp!,{r0-r5,sl,fp,lr} /* restore the stack */ > mov pc, ip /* jump to the new address */ > >
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