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Commit ac180540 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

Revert "x86/refcount: Work around GCC inlining bug" 



This reverts commit 9e1725b4.

See this commit for details about the revert:

  e769742d ("Revert "x86/jump-labels: Macrofy inline assembly code to work around GCC inlining bugs"")

The conflict resolution for interaction with:

  288e4521: ("x86/asm: 'Simplify' GEN_*_RMWcc() macros")

was provided by Masahiro Yamada.

 Conflicts:
	arch/x86/include/asm/refcount.h

Reported-by: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: default avatarBorislav Petkov <bp@alien8.de>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Richard Biener <rguenther@suse.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Segher Boessenkool <segher@kernel.crashing.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Nadav Amit <namit@vmware.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 851a4cd7

arch/x86/include/asm/refcount.h

+33 −48
Original line number Diff line number Diff line
@@ -4,41 +4,6 @@ 
 * x86-specific implementation of refcount_t. Based on PAX_REFCOUNT from

 * PaX/grsecurity.

 */



#ifdef __ASSEMBLY__



#include <asm/asm.h>

#include <asm/bug.h>



.macro REFCOUNT_EXCEPTION counter:req

	.pushsection .text..refcount

111:	lea \counter, %_ASM_CX

112:	ud2

	ASM_UNREACHABLE

	.popsection

113:	_ASM_EXTABLE_REFCOUNT(112b, 113b)

.endm



/* Trigger refcount exception if refcount result is negative. */

.macro REFCOUNT_CHECK_LT_ZERO counter:req

	js 111f

	REFCOUNT_EXCEPTION counter="\counter"

.endm



/* Trigger refcount exception if refcount result is zero or negative. */

.macro REFCOUNT_CHECK_LE_ZERO counter:req

	jz 111f

	REFCOUNT_CHECK_LT_ZERO counter="\counter"

.endm



/* Trigger refcount exception unconditionally. */

.macro REFCOUNT_ERROR counter:req

	jmp 111f

	REFCOUNT_EXCEPTION counter="\counter"

.endm



#else /* __ASSEMBLY__ */



#include <linux/refcount.h>

#include <asm/bug.h>
@@ -50,12 +15,35 @@ 
 * central refcount exception. The fixup address for the exception points

 * back to the regular execution flow in .text.

 */

#define _REFCOUNT_EXCEPTION				\

	".pushsection .text..refcount\n"		\

	"111:\tlea %[var], %%" _ASM_CX "\n"		\

	"112:\t" ASM_UD2 "\n"				\

	ASM_UNREACHABLE					\

	".popsection\n"					\

	"113:\n"					\

	_ASM_EXTABLE_REFCOUNT(112b, 113b)



/* Trigger refcount exception if refcount result is negative. */

#define REFCOUNT_CHECK_LT_ZERO				\

	"js 111f\n\t"					\

	_REFCOUNT_EXCEPTION



/* Trigger refcount exception if refcount result is zero or negative. */

#define REFCOUNT_CHECK_LE_ZERO				\

	"jz 111f\n\t"					\

	REFCOUNT_CHECK_LT_ZERO



/* Trigger refcount exception unconditionally. */

#define REFCOUNT_ERROR					\

	"jmp 111f\n\t"					\

	_REFCOUNT_EXCEPTION



static __always_inline void refcount_add(unsigned int i, refcount_t *r)

{

	asm volatile(LOCK_PREFIX "addl %1,%0\n\t"

		"REFCOUNT_CHECK_LT_ZERO counter=\"%[counter]\""

		: [counter] "+m" (r->refs.counter)

		REFCOUNT_CHECK_LT_ZERO

		: [var] "+m" (r->refs.counter)

		: "ir" (i)

		: "cc", "cx");

}
@@ -63,32 +51,31 @@ static __always_inline void refcount_add(unsigned int i, refcount_t *r) 
static __always_inline void refcount_inc(refcount_t *r)

{

	asm volatile(LOCK_PREFIX "incl %0\n\t"

		"REFCOUNT_CHECK_LT_ZERO counter=\"%[counter]\""

		: [counter] "+m" (r->refs.counter)

		REFCOUNT_CHECK_LT_ZERO

		: [var] "+m" (r->refs.counter)

		: : "cc", "cx");

}



static __always_inline void refcount_dec(refcount_t *r)

{

	asm volatile(LOCK_PREFIX "decl %0\n\t"

		"REFCOUNT_CHECK_LE_ZERO counter=\"%[counter]\""

		: [counter] "+m" (r->refs.counter)

		REFCOUNT_CHECK_LE_ZERO

		: [var] "+m" (r->refs.counter)

		: : "cc", "cx");

}



static __always_inline __must_check

bool refcount_sub_and_test(unsigned int i, refcount_t *r)

{



	return GEN_BINARY_SUFFIXED_RMWcc(LOCK_PREFIX "subl",

					 "REFCOUNT_CHECK_LT_ZERO counter=\"%[var]\"",

					 REFCOUNT_CHECK_LT_ZERO,

					 r->refs.counter, e, "er", i, "cx");

}



static __always_inline __must_check bool refcount_dec_and_test(refcount_t *r)

{

	return GEN_UNARY_SUFFIXED_RMWcc(LOCK_PREFIX "decl",

					"REFCOUNT_CHECK_LT_ZERO counter=\"%[var]\"",

					REFCOUNT_CHECK_LT_ZERO,

					r->refs.counter, e, "cx");

}
@@ -106,8 +93,8 @@ bool refcount_add_not_zero(unsigned int i, refcount_t *r) 


		/* Did we try to increment from/to an undesirable state? */

		if (unlikely(c < 0 || c == INT_MAX || result < c)) {

			asm volatile("REFCOUNT_ERROR counter=\"%[counter]\""

				     : : [counter] "m" (r->refs.counter)

			asm volatile(REFCOUNT_ERROR

				     : : [var] "m" (r->refs.counter)

				     : "cc", "cx");

			break;

		}
@@ -122,6 +109,4 @@ static __always_inline __must_check bool refcount_inc_not_zero(refcount_t *r) 
	return refcount_add_not_zero(1, r);

}



#endif /* __ASSEMBLY__ */



#endif

arch/x86/kernel/macros.S

+0 −1
Original line number Diff line number Diff line
@@ -7,4 +7,3 @@ 
 */



#include <linux/compiler.h>
 
#include <asm/refcount.h>