Date: Mon, 30 Sep 2002 17:16:10 -0400 From: Daniel Eischen <eischen@vigrid.com> To: current@freebsd.org Subject: Longer term fix for sigreturn ABI breaking Message-ID: <3D98BF1A.4A58EE74@vigrid.com>
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At the end is a potentially longer term fix for the ABI
breakage that was introduced when the i386 mcontext_t
was changed/enlarged.
Someone other than I (Bruce?) should vet this. It should
solve the libc_r binary compatibility problem, but it may
not fix everything. Applications that copy ucontext_t's
around (without changing corrupting the mc_fpformat field)
will still break, but there may not be many (if any) of
those.
--
Dan Eischen
Index: i386/i386/machdep.c
===================================================================
RCS file: /opt/d/CVS/src/sys/i386/i386/machdep.c,v
retrieving revision 1.539
diff -u -r1.539 machdep.c
--- i386/i386/machdep.c 30 Sep 2002 07:02:22 -0000 1.539
+++ i386/i386/machdep.c 30 Sep 2002 20:42:30 -0000
@@ -680,7 +680,7 @@
struct proc *p = td->td_proc;
struct trapframe *regs;
const ucontext_t *ucp;
- int cs, eflags, error, ret;
+ int cs, eflags, error;
error = copyin(uap->sigcntxp, &uc, sizeof(uc));
if (error != 0)
@@ -754,9 +754,15 @@
return (EINVAL);
}
- ret = set_fpcontext(td, &ucp->uc_mcontext);
- if (ret != 0)
- return (ret);
+ /*
+ * Intentionally ignore the error to keep binary
+ * compatibility with applications that fiddle with
+ * the FPU save area in the context. The kernel
+ * now saves the FPU state in the context, but it
+ * gets corrupted by those applications that try
+ * to work around the kernel NOT saving it.
+ */
+ (void)set_fpcontext(td, &ucp->uc_mcontext);
bcopy(&ucp->uc_mcontext.mc_fs, regs, sizeof(*regs));
}
@@ -2109,7 +2115,7 @@
* Set machine context.
*
* However, we don't set any but the user modifyable flags, and
- * we we won't touch the cs selector.
+ * we won't touch the cs selector.
*/
int
set_mcontext(struct thread *td, const mcontext_t *mcp)
@@ -2147,10 +2153,6 @@
static void
get_fpcontext(struct thread *td, mcontext_t *mcp)
{
-#if 1 /* XXX: tmp hack to restore ability to run releng4 binaries */
- /* For now, always store the FP state in the PCB. */
- (void)npxgetregs(td, (union savefpu *)&td->td_pcb->pcb_save);
-#else
#ifndef DEV_NPX
mcp->mc_fpformat = _MC_FPFMT_NODEV;
mcp->mc_ownedfp = _MC_FPOWNED_NONE;
@@ -2186,16 +2188,11 @@
}
mcp->mc_fpformat = npxformat();
#endif
-#endif /* tmp hack to restore ability to run releng4 binaries */
}
static int
set_fpcontext(struct thread *td, const mcontext_t *mcp)
{
-#if 1 /* XXX: tmp hack to restore ability to run releng4 binaries */
- /* For now, the FP state is always stored in the PCB. */
- npxsetregs(td, (union savefpu *)&td->td_pcb->pcb_save);
-#else
union savefpu *addr;
if (mcp->mc_fpformat == _MC_FPFMT_NODEV)
@@ -2234,7 +2231,6 @@
*/
} else
return (EINVAL);
-#endif /* tmp hack to restore ability to run releng4 binaries */
return (0);
}
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