Commit 48280042 authored by Andrew Cooper's avatar Andrew Cooper Committed by Borislav Petkov
Browse files

x86/fpu/xstate: Fix XSTATE_WARN_ON() to emit relevant diagnostics 



"XSAVE consistency problem" has been reported under Xen, but that's the extent
of my divination skills.

Modify XSTATE_WARN_ON() to force the caller to provide relevant diagnostic
information, and modify each caller suitably.

For check_xstate_against_struct(), this removes a double WARN() where one will
do perfectly fine.

CC stable as this has been wonky debugging for 7 years and it is good to
have there too.

Signed-off-by: default avatarAndrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220810221909.12768-1-andrew.cooper3@citrix.com
parent f0c4d9fc

arch/x86/kernel/fpu/xstate.c

+6 −6
Original line number Diff line number Diff line
@@ -440,8 +440,8 @@ static void __init __xstate_dump_leaves(void) 
	}

}



#define XSTATE_WARN_ON(x) do {							\

	if (WARN_ONCE(x, "XSAVE consistency problem, dumping leaves")) {	\

#define XSTATE_WARN_ON(x, fmt, ...) do {					\

	if (WARN_ONCE(x, "XSAVE consistency problem: " fmt, ##__VA_ARGS__)) {	\

		__xstate_dump_leaves();						\

	}									\

} while (0)
@@ -554,8 +554,7 @@ static bool __init check_xstate_against_struct(int nr) 
	    (nr >= XFEATURE_MAX) ||

	    (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) ||

	    ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) {

		WARN_ONCE(1, "no structure for xstate: %d\n", nr);

		XSTATE_WARN_ON(1);

		XSTATE_WARN_ON(1, "No structure for xstate: %d\n", nr);

		return false;

	}

	return true;
@@ -598,12 +597,13 @@ static bool __init paranoid_xstate_size_valid(unsigned int kernel_size) 
		 * XSAVES.

		 */

		if (!xsaves && xfeature_is_supervisor(i)) {

			XSTATE_WARN_ON(1);

			XSTATE_WARN_ON(1, "Got supervisor feature %d, but XSAVES not advertised\n", i);

			return false;

		}

	}

	size = xstate_calculate_size(fpu_kernel_cfg.max_features, compacted);

	XSTATE_WARN_ON(size != kernel_size);

	XSTATE_WARN_ON(size != kernel_size,

		       "size %u != kernel_size %u\n", size, kernel_size);

	return size == kernel_size;

}