x86, asm: Refactor atomic64_386_32.S to support old binutils and be cleaner

The old code didn't work on binutils 2.12 because setting a symbol to
a register apparently requires a fairly recent version.

This commit refactors the code to use the C preprocessor instead, and
in the process makes the whole code a bit easier to understand.

The object code produced is unchanged as expected.

This fixes kernel bugzilla 16506.

Reported-by: Dieter Stussy <kd6lvw+software@kd6lvw.ampr.org>
Signed-off-by: Luca Barbieri <luca@luca-barbieri.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: <stable@kernel.org> 2.6.35
LKML-Reference: <tip-*@git.kernel.org>

diff --git a/arch/x86/lib/atomic64_386_32.S b/arch/x86/lib/atomic64_386_32.S
index 4a5979a..78ee8e0 100644 (file)
--- a/arch/x86/lib/atomic64_386_32.S
+++ b/arch/x86/lib/atomic64_386_32.S
@@ -25,150 +25,170 @@
        CFI_ADJUST_CFA_OFFSET -4
 .endm
 
-.macro BEGIN func reg
-$v = \reg
-
-ENTRY(atomic64_\func\()_386)
-       CFI_STARTPROC
-       LOCK $v
-
-.macro RETURN
-       UNLOCK $v
+#define BEGIN(op) \
+.macro END; \
+       CFI_ENDPROC; \
+ENDPROC(atomic64_##op##_386); \
+.purgem END; \
+.endm; \
+ENTRY(atomic64_##op##_386); \
+       CFI_STARTPROC; \
+       LOCK v;
+
+#define RET \
+       UNLOCK v; \
        ret
-.endm
-
-.macro END_
-       CFI_ENDPROC
-ENDPROC(atomic64_\func\()_386)
-.purgem RETURN
-.purgem END_
-.purgem END
-.endm
-
-.macro END
-RETURN
-END_
-.endm
-.endm
-
-BEGIN read %ecx
-       movl  ($v), %eax
-       movl 4($v), %edx
-END
-
-BEGIN set %esi
-       movl %ebx,  ($v)
-       movl %ecx, 4($v)
-END
-
-BEGIN xchg %esi
-       movl  ($v), %eax
-       movl 4($v), %edx
-       movl %ebx,  ($v)
-       movl %ecx, 4($v)
-END
-
-BEGIN add %ecx
-       addl %eax,  ($v)
-       adcl %edx, 4($v)
-END
 
-BEGIN add_return %ecx
-       addl  ($v), %eax
-       adcl 4($v), %edx
-       movl %eax,  ($v)
-       movl %edx, 4($v)
-END
-
-BEGIN sub %ecx
-       subl %eax,  ($v)
-       sbbl %edx, 4($v)
-END
-
-BEGIN sub_return %ecx
+#define RET_END \
+       RET; \
+       END
+
+#define v %ecx
+BEGIN(read)
+       movl  (v), %eax
+       movl 4(v), %edx
+RET_END
+#undef v
+
+#define v %esi
+BEGIN(set)
+       movl %ebx,  (v)
+       movl %ecx, 4(v)
+RET_END
+#undef v
+
+#define v  %esi
+BEGIN(xchg)
+       movl  (v), %eax
+       movl 4(v), %edx
+       movl %ebx,  (v)
+       movl %ecx, 4(v)
+RET_END
+#undef v
+
+#define v %ecx
+BEGIN(add)
+       addl %eax,  (v)
+       adcl %edx, 4(v)
+RET_END
+#undef v
+
+#define v %ecx
+BEGIN(add_return)
+       addl  (v), %eax
+       adcl 4(v), %edx
+       movl %eax,  (v)
+       movl %edx, 4(v)
+RET_END
+#undef v
+
+#define v %ecx
+BEGIN(sub)
+       subl %eax,  (v)
+       sbbl %edx, 4(v)
+RET_END
+#undef v
+
+#define v %ecx
+BEGIN(sub_return)
        negl %edx
        negl %eax
        sbbl $0, %edx
-       addl  ($v), %eax
-       adcl 4($v), %edx
-       movl %eax,  ($v)
-       movl %edx, 4($v)
-END
-
-BEGIN inc %esi
-       addl $1,  ($v)
-       adcl $0, 4($v)
-END
-
-BEGIN inc_return %esi
-       movl  ($v), %eax
-       movl 4($v), %edx
+       addl  (v), %eax
+       adcl 4(v), %edx
+       movl %eax,  (v)
+       movl %edx, 4(v)
+RET_END
+#undef v
+
+#define v %esi
+BEGIN(inc)
+       addl $1,  (v)
+       adcl $0, 4(v)
+RET_END
+#undef v
+
+#define v %esi
+BEGIN(inc_return)
+       movl  (v), %eax
+       movl 4(v), %edx
        addl $1, %eax
        adcl $0, %edx
-       movl %eax,  ($v)
-       movl %edx, 4($v)
-END
-
-BEGIN dec %esi
-       subl $1,  ($v)
-       sbbl $0, 4($v)
-END
-
-BEGIN dec_return %esi
-       movl  ($v), %eax
-       movl 4($v), %edx
+       movl %eax,  (v)
+       movl %edx, 4(v)
+RET_END
+#undef v
+
+#define v %esi
+BEGIN(dec)
+       subl $1,  (v)
+       sbbl $0, 4(v)
+RET_END
+#undef v
+
+#define v %esi
+BEGIN(dec_return)
+       movl  (v), %eax
+       movl 4(v), %edx
        subl $1, %eax
        sbbl $0, %edx
-       movl %eax,  ($v)
-       movl %edx, 4($v)
-END
+       movl %eax,  (v)
+       movl %edx, 4(v)
+RET_END
+#undef v
 
-BEGIN add_unless %ecx
+#define v %ecx
+BEGIN(add_unless)
        addl %eax, %esi
        adcl %edx, %edi
-       addl  ($v), %eax
-       adcl 4($v), %edx
+       addl  (v), %eax
+       adcl 4(v), %edx
        cmpl %eax, %esi
        je 3f
 1:
-       movl %eax,  ($v)
-       movl %edx, 4($v)
+       movl %eax,  (v)
+       movl %edx, 4(v)
        movl $1, %eax
 2:
-RETURN
+       RET
 3:
        cmpl %edx, %edi
        jne 1b
        xorl %eax, %eax
        jmp 2b
-END_
+END
+#undef v
 
-BEGIN inc_not_zero %esi
-       movl  ($v), %eax
-       movl 4($v), %edx
+#define v %esi
+BEGIN(inc_not_zero)
+       movl  (v), %eax
+       movl 4(v), %edx
        testl %eax, %eax
        je 3f
 1:
        addl $1, %eax
        adcl $0, %edx
-       movl %eax,  ($v)
-       movl %edx, 4($v)
+       movl %eax,  (v)
+       movl %edx, 4(v)
        movl $1, %eax
 2:
-RETURN
+       RET
 3:
        testl %edx, %edx
        jne 1b
        jmp 2b
-END_
+END
+#undef v
 
-BEGIN dec_if_positive %esi
-       movl  ($v), %eax
-       movl 4($v), %edx
+#define v %esi
+BEGIN(dec_if_positive)
+       movl  (v), %eax
+       movl 4(v), %edx
        subl $1, %eax
        sbbl $0, %edx
        js 1f
-       movl %eax,  ($v)
-       movl %edx, 4($v)
+       movl %eax,  (v)
+       movl %edx, 4(v)
 1:
-END
+RET_END
+#undef v