[PATCH 09/13] x86/asm: Convert ALTERNATIVE*() assembler macros to preprocessor macros

From: Josh Poimboeuf
Date: Wed Oct 04 2017 - 12:00:08 EST

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The ALTERNATIVE() and ALTERNATIVE_2() macros are GNU assembler macros,
which makes them quite inflexible for future changes. Convert them to
preprocessor macros.

Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/entry/entry_32.S | 12 +++---
arch/x86/entry/entry_64.S | 10 ++---
arch/x86/entry/entry_64_compat.S | 8 ++--
arch/x86/entry/vdso/vdso32/system_call.S | 10 ++---
arch/x86/include/asm/alternative-asm.h | 68 +++++++++++++++-----------------
arch/x86/include/asm/smap.h | 4 +-
arch/x86/lib/copy_page_64.S | 2 +-
arch/x86/lib/memcpy_64.S | 4 +-
arch/x86/lib/memmove_64.S | 3 +-
arch/x86/lib/memset_64.S | 4 +-
10 files changed, 59 insertions(+), 66 deletions(-)

diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 21d1197779a4..338dc838a9a8 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -443,8 +443,8 @@ ENTRY(entry_SYSENTER_32)
movl %esp, %eax
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
- ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \
- "jmp .Lsyscall_32_done", X86_FEATURE_XENPV
+ #define JMP_IF_IRET testl %eax, %eax; jz .Lsyscall_32_done
+ ALTERNATIVE(JMP_IF_IRET, jmp .Lsyscall_32_done, X86_FEATURE_XENPV)

/* Opportunistic SYSEXIT */
TRACE_IRQS_ON /* User mode traces as IRQs on. */
@@ -536,7 +536,7 @@ restore_all:
TRACE_IRQS_IRET
.Lrestore_all_notrace:
#ifdef CONFIG_X86_ESPFIX32
- ALTERNATIVE "jmp .Lrestore_nocheck", "", X86_BUG_ESPFIX
+ ALTERNATIVE(jmp .Lrestore_nocheck, , X86_BUG_ESPFIX)

movl PT_EFLAGS(%esp), %eax # mix EFLAGS, SS and CS
/*
@@ -692,9 +692,9 @@ ENTRY(simd_coprocessor_error)
pushl $0
#ifdef CONFIG_X86_INVD_BUG
/* AMD 486 bug: invd from userspace calls exception 19 instead of #GP */
- ALTERNATIVE "pushl $do_general_protection", \
- "pushl $do_simd_coprocessor_error", \
- X86_FEATURE_XMM
+ ALTERNATIVE(pushl $do_general_protection,
+ pushl $do_simd_coprocessor_error,
+ X86_FEATURE_XMM)
#else
pushl $do_simd_coprocessor_error
#endif
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index c7c85724d7e0..49733c72619a 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -925,7 +925,7 @@ ENTRY(native_load_gs_index)
SWAPGS
.Lgs_change:
movl %edi, %gs
-2: ALTERNATIVE "", "mfence", X86_BUG_SWAPGS_FENCE
+2: ALTERNATIVE(, mfence, X86_BUG_SWAPGS_FENCE)
SWAPGS
popfq
FRAME_END
@@ -938,12 +938,8 @@ EXPORT_SYMBOL(native_load_gs_index)
/* running with kernelgs */
bad_gs:
SWAPGS /* switch back to user gs */
-.macro ZAP_GS
- /* This can't be a string because the preprocessor needs to see it. */
- movl $__USER_DS, %eax
- movl %eax, %gs
-.endm
- ALTERNATIVE "", "ZAP_GS", X86_BUG_NULL_SEG
+ #define ZAP_GS movl $__USER_DS, %eax; movl %eax, %gs
+ ALTERNATIVE(, ZAP_GS, X86_BUG_NULL_SEG)
xorl %eax, %eax
movl %eax, %gs
jmp 2b
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 4d9385529c39..16e82b5103b5 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -124,8 +124,8 @@ ENTRY(entry_SYSENTER_compat)
movq %rsp, %rdi
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
- ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \
- "jmp .Lsyscall_32_done", X86_FEATURE_XENPV
+ #define JMP_IF_IRET testl %eax, %eax; jz .Lsyscall_32_done
+ ALTERNATIVE(JMP_IF_IRET, jmp .Lsyscall_32_done, X86_FEATURE_XENPV)
jmp sysret32_from_system_call

.Lsysenter_fix_flags:
@@ -224,8 +224,8 @@ GLOBAL(entry_SYSCALL_compat_after_hwframe)
movq %rsp, %rdi
call do_fast_syscall_32
/* XEN PV guests always use IRET path */
- ALTERNATIVE "testl %eax, %eax; jz .Lsyscall_32_done", \
- "jmp .Lsyscall_32_done", X86_FEATURE_XENPV
+ ALTERNATIVE(JMP_IF_IRET,
+ jmp .Lsyscall_32_done, X86_FEATURE_XENPV)

/* Opportunistic SYSRET */
sysret32_from_system_call:
diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S
index ed4bc9731cbb..a0c5f9e8226c 100644
--- a/arch/x86/entry/vdso/vdso32/system_call.S
+++ b/arch/x86/entry/vdso/vdso32/system_call.S
@@ -48,15 +48,15 @@ __kernel_vsyscall:
CFI_ADJUST_CFA_OFFSET 4
CFI_REL_OFFSET ebp, 0

- #define SYSENTER_SEQUENCE "movl %esp, %ebp; sysenter"
- #define SYSCALL_SEQUENCE "movl %ecx, %ebp; syscall"
+ #define SYSENTER_SEQUENCE movl %esp, %ebp; sysenter
+ #define SYSCALL_SEQUENCE movl %ecx, %ebp; syscall

#ifdef CONFIG_X86_64
/* If SYSENTER (Intel) or SYSCALL32 (AMD) is available, use it. */
- ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSENTER32, \
- SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32
+ ALTERNATIVE_2(, SYSENTER_SEQUENCE, X86_FEATURE_SYSENTER32,
+ SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32)
#else
- ALTERNATIVE "", SYSENTER_SEQUENCE, X86_FEATURE_SEP
+ ALTERNATIVE(, SYSENTER_SEQUENCE, X86_FEATURE_SEP)
#endif

/* Enter using int $0x80 */
diff --git a/arch/x86/include/asm/alternative-asm.h b/arch/x86/include/asm/alternative-asm.h
index e7636bac7372..60073947350d 100644
--- a/arch/x86/include/asm/alternative-asm.h
+++ b/arch/x86/include/asm/alternative-asm.h
@@ -39,23 +39,21 @@
* @newinstr. ".skip" directive takes care of proper instruction padding
* in case @newinstr is longer than @oldinstr.
*/
-.macro ALTERNATIVE oldinstr, newinstr, feature
-140:
- \oldinstr
-141:
- .skip -(((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)),0x90
-142:
-
- .pushsection .altinstructions,"a"
- altinstruction_entry 140b,143f,\feature,142b-140b,144f-143f,142b-141b
- .popsection
-
- .pushsection .altinstr_replacement,"ax"
-143:
- \newinstr
-144:
+#define ALTERNATIVE(oldinstr, newinstr, feature) \
+140:; \
+ oldinstr; \
+141:; \
+ .skip -(((144f-143f)-(141b-140b)) > 0) * \
+ ((144f-143f)-(141b-140b)),0x90; \
+142:; \
+ .pushsection .altinstructions, "a"; \
+ altinstruction_entry 140b,143f,feature,142b-140b,144f-143f,142b-141b;\
+ .popsection; \
+ .pushsection .altinstr_replacement, "ax"; \
+143:; \
+ newinstr; \
+144:; \
.popsection
-.endm

#define old_len 141b-140b
#define new_len1 144f-143f
@@ -73,27 +71,25 @@
* has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
* @feature2, it replaces @oldinstr with @feature2.
*/
-.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
-140:
- \oldinstr
-141:
- .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
- (alt_max_short(new_len1, new_len2) - (old_len)),0x90
-142:
-
- .pushsection .altinstructions,"a"
- altinstruction_entry 140b,143f,\feature1,142b-140b,144f-143f,142b-141b
- altinstruction_entry 140b,144f,\feature2,142b-140b,145f-144f,142b-141b
- .popsection
-
- .pushsection .altinstr_replacement,"ax"
-143:
- \newinstr1
-144:
- \newinstr2
-145:
+#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
+ newinstr2, feature2) \
+140:; \
+ oldinstr; \
+141:; \
+ .skip -((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
+ (alt_max_short(new_len1, new_len2) - (old_len)),0x90; \
+142:; \
+ .pushsection .altinstructions, "a"; \
+ altinstruction_entry 140b,143f,feature1,142b-140b,144f-143f,142b-141b; \
+ altinstruction_entry 140b,144f,feature2,142b-140b,145f-144f,142b-141b; \
+ .popsection; \
+ .pushsection .altinstr_replacement, "ax"; \
+143:; \
+ newinstr1; \
+144:; \
+ newinstr2; \
+145:; \
.popsection
-.endm

#endif /* __ASSEMBLY__ */

diff --git a/arch/x86/include/asm/smap.h b/arch/x86/include/asm/smap.h
index db333300bd4b..b1264cff8906 100644
--- a/arch/x86/include/asm/smap.h
+++ b/arch/x86/include/asm/smap.h
@@ -28,10 +28,10 @@
#ifdef CONFIG_X86_SMAP

#define ASM_CLAC \
- ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
+ ALTERNATIVE(, __ASM_CLAC, X86_FEATURE_SMAP)

#define ASM_STAC \
- ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
+ ALTERNATIVE(, __ASM_STAC, X86_FEATURE_SMAP)

#else /* CONFIG_X86_SMAP */

diff --git a/arch/x86/lib/copy_page_64.S b/arch/x86/lib/copy_page_64.S
index e8508156c99d..0611dee51760 100644
--- a/arch/x86/lib/copy_page_64.S
+++ b/arch/x86/lib/copy_page_64.S
@@ -13,7 +13,7 @@
*/
ALIGN
ENTRY(copy_page)
- ALTERNATIVE "jmp copy_page_regs", "", X86_FEATURE_REP_GOOD
+ ALTERNATIVE(jmp copy_page_regs, , X86_FEATURE_REP_GOOD)
movl $4096/8, %ecx
rep movsq
ret
diff --git a/arch/x86/lib/memcpy_64.S b/arch/x86/lib/memcpy_64.S
index 9a53a06e5a3e..7ada0513864b 100644
--- a/arch/x86/lib/memcpy_64.S
+++ b/arch/x86/lib/memcpy_64.S
@@ -28,8 +28,8 @@
*/
ENTRY(__memcpy)
ENTRY(memcpy)
- ALTERNATIVE_2 "jmp memcpy_orig", "", X86_FEATURE_REP_GOOD, \
- "jmp memcpy_erms", X86_FEATURE_ERMS
+ ALTERNATIVE_2(jmp memcpy_orig, , X86_FEATURE_REP_GOOD,
+ jmp memcpy_erms, X86_FEATURE_ERMS)

movq %rdi, %rax
movq %rdx, %rcx
diff --git a/arch/x86/lib/memmove_64.S b/arch/x86/lib/memmove_64.S
index 15de86cd15b0..ca6c39effa2f 100644
--- a/arch/x86/lib/memmove_64.S
+++ b/arch/x86/lib/memmove_64.S
@@ -42,7 +42,8 @@ ENTRY(__memmove)
jg 2f

.Lmemmove_begin_forward:
- ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS
+ #define ERMS_MOVSB_RET movq %rdx, %rcx; rep movsb; retq
+ ALTERNATIVE(, ERMS_MOVSB_RET, X86_FEATURE_ERMS)

/*
* movsq instruction have many startup latency
diff --git a/arch/x86/lib/memset_64.S b/arch/x86/lib/memset_64.S
index 55b95db30a61..d86825a11724 100644
--- a/arch/x86/lib/memset_64.S
+++ b/arch/x86/lib/memset_64.S
@@ -26,8 +26,8 @@ ENTRY(__memset)
*
* Otherwise, use original memset function.
*/
- ALTERNATIVE_2 "jmp memset_orig", "", X86_FEATURE_REP_GOOD, \
- "jmp memset_erms", X86_FEATURE_ERMS
+ ALTERNATIVE_2(jmp memset_orig, , X86_FEATURE_REP_GOOD,
+ jmp memset_erms, X86_FEATURE_ERMS)

movq %rdi,%r9
movq %rdx,%rcx
--
2.13.6

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