sparc64: Do not define thread fpregs save area as zero-length array.

This breaks the stack end corruption detection facility.

What that facility does it write a magic value to "end_of_stack()"
and checking to see if it gets overwritten.

"end_of_stack()" is "task_thread_info(p) + 1", which for sparc64 is
the beginning of the FPU register save area.

So once the user uses the FPU, the magic value is overwritten and the
debug checks trigger.

Fix this by making the size explicit.

Due to the size we use for the fpsaved[], gsr[], and xfsr[] arrays we
are limited to 7 levels of FPU state saves.  So each FPU register set
is 256 bytes, allocate 256 * 7 for the fpregs area.

Reported-by: Meelis Roos <mroos@linux.ee>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/include/asm/thread_info_64.h b/arch/sparc/include/asm/thread_info_64.h
index f85dc8512ab3f6fdea1f1430aa8141bdccec2d44..cc6275c931a5782037678abebb9710fff392dad1 100644 (file)
--- a/arch/sparc/include/asm/thread_info_64.h
+++ b/arch/sparc/include/asm/thread_info_64.h
@@ -63,7 +63,8 @@ struct thread_info {
        struct pt_regs          *kern_una_regs;
        unsigned int            kern_una_insn;
 
-       unsigned long           fpregs[0] __attribute__ ((aligned(64)));
+       unsigned long           fpregs[(7 * 256) / sizeof(unsigned long)]
+               __attribute__ ((aligned(64)));
 };
 
 #endif /* !(__ASSEMBLY__) */