fxsave/xsave instructions will not touch all the bytes in the fxsave/xsave frame. Clear the user buffer before doing fxsave/xsave directly to user buffer during the sigcontext setup. This is essentially needed in the context of xsave(for example, some of the fields in the xsave header are not touched by the xsave and defined as must be zero). This will also present uniform and clean context to the user (from which user can safely do fxrstor/xrstor). Signed-off-by: Suresh Siddha --- Index: tip/arch/x86/kernel/xsave.c =================================================================== --- tip.orig/arch/x86/kernel/xsave.c 2008-08-11 15:26:47.000000000 -0700 +++ tip/arch/x86/kernel/xsave.c 2008-08-11 15:44:33.000000000 -0700 @@ -92,6 +92,12 @@ return 0; clear_used_math(); /* trigger finit */ if (task_thread_info(tsk)->status & TS_USEDFPU) { + /* + * Start with clearing the user buffer. This will present a + * clean context for the bytes not touched by the fxsave/xsave. + */ + __clear_user(buf, sig_xstate_size); + if (task_thread_info(tsk)->status & TS_XSAVE) err = xsave_user(buf); else -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/