x86/asm: Add suffix macro for GEN_*_RMWcc()

The coming x86 refcount protection needs to be able to add trailing
instructions to the GEN_*_RMWcc() operations. This extracts the
difference between the goto/non-goto cases so the helper macros
can be defined outside the #ifdef cases. Additionally adds argument
naming to the resulting asm for referencing from suffixed
instructions, and adds clobbers for "cc", and "cx" to let suffixes
use _ASM_CX, and retain any set flags.

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Elena Reshetova <elena.reshetova@intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Hans Liljestrand <ishkamiel@gmail.com>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Jann Horn <jannh@google.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arozansk@redhat.com
Cc: axboe@kernel.dk
Cc: kernel-hardening@lists.openwall.com
Cc: linux-arch <linux-arch@vger.kernel.org>
Link: http://lkml.kernel.org/r/1500921349-10803-2-git-send-email-keescook@chromium.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/rmwcc.h b/arch/x86/include/asm/rmwcc.h
index 661dd305694af8878b8cdcd8b9396b9c7da3b646..045f99211a9921cfd4eddb7250ff4ed56a602c2a 100644 (file)
--- a/arch/x86/include/asm/rmwcc.h
+++ b/arch/x86/include/asm/rmwcc.h
@@ -1,45 +1,56 @@
 #ifndef _ASM_X86_RMWcc
 #define _ASM_X86_RMWcc
 
+#define __CLOBBERS_MEM         "memory"
+#define __CLOBBERS_MEM_CC_CX   "memory", "cc", "cx"
+
 #if !defined(__GCC_ASM_FLAG_OUTPUTS__) && defined(CC_HAVE_ASM_GOTO)
 
 /* Use asm goto */
 
-#define __GEN_RMWcc(fullop, var, cc, ...)                              \
+#define __GEN_RMWcc(fullop, var, cc, clobbers, ...)                    \
 do {                                                                   \
        asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"             \
-                       : : "m" (var), ## __VA_ARGS__                   \
-                       : "memory" : cc_label);                         \
+                       : : [counter] "m" (var), ## __VA_ARGS__         \
+                       : clobbers : cc_label);                         \
        return 0;                                                       \
 cc_label:                                                              \
        return 1;                                                       \
 } while (0)
 
-#define GEN_UNARY_RMWcc(op, var, arg0, cc)                             \
-       __GEN_RMWcc(op " " arg0, var, cc)
+#define __BINARY_RMWcc_ARG     " %1, "
 
-#define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                 \
-       __GEN_RMWcc(op " %1, " arg0, var, cc, vcon (val))
 
 #else /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
 
 /* Use flags output or a set instruction */
 
-#define __GEN_RMWcc(fullop, var, cc, ...)                              \
+#define __GEN_RMWcc(fullop, var, cc, clobbers, ...)                    \
 do {                                                                   \
        bool c;                                                         \
        asm volatile (fullop ";" CC_SET(cc)                             \
-                       : "+m" (var), CC_OUT(cc) (c)                    \
-                       : __VA_ARGS__ : "memory");                      \
+                       : [counter] "+m" (var), CC_OUT(cc) (c)          \
+                       : __VA_ARGS__ : clobbers);                      \
        return c;                                                       \
 } while (0)
 
+#define __BINARY_RMWcc_ARG     " %2, "
+
+#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
+
 #define GEN_UNARY_RMWcc(op, var, arg0, cc)                             \
-       __GEN_RMWcc(op " " arg0, var, cc)
+       __GEN_RMWcc(op " " arg0, var, cc, __CLOBBERS_MEM)
+
+#define GEN_UNARY_SUFFIXED_RMWcc(op, suffix, var, arg0, cc)            \
+       __GEN_RMWcc(op " " arg0 "\n\t" suffix, var, cc,                 \
+                   __CLOBBERS_MEM_CC_CX)
 
 #define GEN_BINARY_RMWcc(op, var, vcon, val, arg0, cc)                 \
-       __GEN_RMWcc(op " %2, " arg0, var, cc, vcon (val))
+       __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0, var, cc,                \
+                   __CLOBBERS_MEM, vcon (val))
 
-#endif /* defined(__GCC_ASM_FLAG_OUTPUTS__) || !defined(CC_HAVE_ASM_GOTO) */
+#define GEN_BINARY_SUFFIXED_RMWcc(op, suffix, var, vcon, val, arg0, cc)        \
+       __GEN_RMWcc(op __BINARY_RMWcc_ARG arg0 "\n\t" suffix, var, cc,  \
+                   __CLOBBERS_MEM_CC_CX, vcon (val))
 
 #endif /* _ASM_X86_RMWcc */