[PATCH] i386: fix broken FP exception handling (543f2a33) · Commits · 戴 / test

The FXSAVE information leak patch introduced a bug in FP exception handling: it clears FP exceptions only when there are already none outstanding. Mikael Pettersson reported that causes problems with the Erlang runtime and has tested this fix. Signed-off-by:

Chuck Ebbert <76306.1226@compuserve.com> Acked-by:

Mikael Pettersson <mikpe@it.uu.se> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

include/asm-i386/i387.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -58,13 +58,13 @@ static inline void __save_init_fpu( struct task_struct *tsk )
		alternative_input(
		"fnsave %[fx] ;fwait;" GENERIC_NOP8 GENERIC_NOP4,
		"fxsave %[fx]\n"
		"bt $7,%[fsw] ; jc 1f ; fnclex\n1:",
		"bt $7,%[fsw] ; jnc 1f ; fnclex\n1:",
		X86_FEATURE_FXSR,
		[fx] "m" (tsk->thread.i387.fxsave),
		[fsw] "m" (tsk->thread.i387.fxsave.swd) : "memory");
		/* AMD K7/K8 CPUs don't save/restore FDP/FIP/FOP unless an exception
		is pending. Clear the x87 state here by setting it to fixed
		values. __per_cpu_offset[0] is a random variable that should be in L1 */
		values. safe_address is a random variable that should be in L1 */
		alternative_input(
		GENERIC_NOP8 GENERIC_NOP2,
		"emms\n\t" /* clear stack tags */

Admin message