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ld.lld: error: <inline asm>:25:2: macro 'extable_type_reg' is already defined #1513

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nathanchance opened this issue Nov 24, 2021 · 4 comments
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ld.lld: error: <inline asm>:25:2: macro 'extable_type_reg' is already defined #1513

nathanchance opened this issue Nov 24, 2021 · 4 comments
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@nathanchance
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[BUG] linux-next This is an issue only seen in linux-next [FEATURE] LTO Related to building the kernel with LLVM Link Time Optimization [FIXED][LINUX] development cycle This bug was only present and fixed in a -next or -rc cycle [Reported-by] kbuild test robot Reported-by: kbuild test robot <[email protected]> [TOOL] integrated-as The issue is relevant to LLVM integrated assembler

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@nathanchance
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The kernel test robot reported an issue with a proposed series:

$ git fetch https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/wip.extable

$ git checkout 04a71fc5f69191cb18f97c0ae4e4c941fe335f4e

$ curl -LSs https://lore.kernel.org/all/[email protected]/2-a.bin | gzip -d > .config

$ make -skj"$(nproc)" LLVM=1 LLVM_IAS=1 olddefconfig vmlinux
ld.lld: error: <inline asm>:64:2: macro 'extable_type_reg' is already defined
        .macro extable_type_reg type:req reg:req
        ^

It looks like something similar to commit be604c616ca7 ("arm64: sysreg: Make mrs_s and msr_s macros work with Clang and LTO") will be needed here.

I tried something like

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 95bb23082b87..88a030c22bb2 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -152,30 +152,37 @@
 
 #else /* ! __ASSEMBLY__ */
 
-asm(
-"	.macro extable_type_reg type:req reg:req\n"
-"	.set found, 0\n"
-"	.set regnr, 0\n"
-"	.irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n"
-"	.ifc \\reg, %\\rs\n"
-"	.set found, found+1\n"
-"	.long \\type + (regnr << 8)\n"
-"	.endif\n"
-"	.set regnr, regnr+1\n"
-"	.endr\n"
-"	.set regnr, 0\n"
-"	.irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n"
-"	.ifc \\reg, %\\rs\n"
-"	.set found, found+1\n"
-"	.long \\type + (regnr << 8)\n"
-"	.endif\n"
-"	.set regnr, regnr+1\n"
-"	.endr\n"
-"	.if (found != 1)\n"
-"	.error \"extable_type_reg: bad register argument\"\n"
-"	.endif\n"
+# define DEFINE_EXTABLE_TYPE_REG \
+"	.macro extable_type_reg type:req reg:req\n"						\
+"	.set found, 0\n"									\
+"	.set regnr, 0\n"									\
+"	.irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n"		\
+"	.ifc \\reg, %\\rs\n"									\
+"	.set found, found+1\n"									\
+"	.long \\type + (regnr << 8)\n"								\
+"	.endif\n"										\
+"	.set regnr, regnr+1\n"									\
+"	.endr\n"										\
+"	.set regnr, 0\n"									\
+"	.irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n"	\
+"	.ifc \\reg, %\\rs\n"									\
+"	.set found, found+1\n"									\
+"	.long \\type + (regnr << 8)\n"								\
+"	.endif\n"										\
+"	.set regnr, regnr+1\n"									\
+"	.endr\n"										\
+"	.if (found != 1)\n"									\
+"	.error \"extable_type_reg: bad register argument\"\n"					\
+"	.endif\n"										\
 "	.endm\n"
-);
+
+# define UNDEFINE_EXTABLE_TYPE_REG \
+"	.purgem extable_type_reg\n"
+
+# define __extable_type_reg(type, reg) \
+	DEFINE_EXTABLE_TYPE_REG								\
+"	extable_type_reg type=" __stringify(type) ", reg=" __stringify(reg) " \n"	\
+	UNDEFINE_EXTABLE_TYPE_REG
 
 # define _ASM_EXTABLE_TYPE(from, to, type)			\
 	" .pushsection \"__ex_table\",\"a\"\n"			\
@@ -185,12 +192,12 @@ asm(
 	" .long " __stringify(type) " \n"			\
 	" .popsection\n"
 
-# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg)				\
-	" .pushsection \"__ex_table\",\"a\"\n"					\
-	" .balign 4\n"								\
-	" .long (" #from ") - .\n"						\
-	" .long (" #to ") - .\n"						\
-	"extable_type_reg reg=" __stringify(reg) ", type=" __stringify(type) " \n"\
+# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg)	\
+	" .pushsection \"__ex_table\",\"a\"\n"		\
+	" .balign 4\n"					\
+	" .long (" #from ") - .\n"			\
+	" .long (" #to ") - .\n"			\
+	__extable_type_reg(type, reg)			\
 	" .popsection\n"
 
 /* For C file, we already have NOKPROBE_SYMBOL macro */

which results in

In file included from arch/x86/kernel/asm-offsets.c:9:
In file included from ./include/linux/crypto.h:20:
In file included from ./include/linux/slab.h:15:
In file included from ./include/linux/gfp.h:6:
In file included from ./include/linux/mmzone.h:8:
In file included from ./include/linux/spinlock.h:55:
In file included from ./include/linux/preempt.h:78:
In file included from ./arch/x86/include/asm/preempt.h:7:
In file included from ./include/linux/thread_info.h:60:
In file included from ./arch/x86/include/asm/thread_info.h:53:
In file included from ./arch/x86/include/asm/cpufeature.h:5:
In file included from ./arch/x86/include/asm/processor.h:22:
./arch/x86/include/asm/msr.h:168:8: error: invalid % escape in inline assembly string
                     _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_WRMSR_SAFE, %[err])
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
./arch/x86/include/asm/asm.h:200:2: note: expanded from macro '_ASM_EXTABLE_TYPE_REG'
        __extable_type_reg(type, reg)                   \
        ^
./arch/x86/include/asm/asm.h:183:2: note: expanded from macro '__extable_type_reg'
        DEFINE_EXTABLE_TYPE_REG                                                         \
        ^
./arch/x86/include/asm/asm.h:160:16: note: expanded from macro 'DEFINE_EXTABLE_TYPE_REG'
"       .ifc \\reg, %\\rs\n"                                                                    \
                     ^
2 errors generated.

after which I tried replacing the % with %% in DEFINE_EXTABLE_TYPE_REG , which appears to break the macro entirely:

<instantiation>:19:2: error: extable_type_reg: bad register argument
        .error "extable_type_reg: bad register argument"
        ^
note: while in macro instantiation
        extable_type_reg type=(17 | ((0) << 16)), reg=%esi
        ^

My knowledge of assembly macros is non-existent so any input around this would be appreciate :)
@nathanchance nathanchance added [TOOL] integrated-as The issue is relevant to LLVM integrated assembler [FEATURE] LTO Related to building the kernel with LLVM Link Time Optimization [Reported-by] kbuild test robot Reported-by: kbuild test robot <[email protected]> labels Nov 24, 2021
@nickdesaulniers
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after which I tried replacing the % with %% in DEFINE_EXTABLE_TYPE_REG , which appears to break the macro entirely:

Did you replace % with %% for BOTH .ifc directives in DEFINE_EXTABLE_TYPE_REG? ;)

@nathanchance
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Did you replace % with %% for BOTH .ifc directives in DEFINE_EXTABLE_TYPE_REG? ;)

Nope... This works!

diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 95bb23082b87..5b06676538ed 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -152,30 +152,37 @@
 
 #else /* ! __ASSEMBLY__ */
 
-asm(
-"	.macro extable_type_reg type:req reg:req\n"
-"	.set found, 0\n"
-"	.set regnr, 0\n"
-"	.irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n"
-"	.ifc \\reg, %\\rs\n"
-"	.set found, found+1\n"
-"	.long \\type + (regnr << 8)\n"
-"	.endif\n"
-"	.set regnr, regnr+1\n"
-"	.endr\n"
-"	.set regnr, 0\n"
-"	.irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n"
-"	.ifc \\reg, %\\rs\n"
-"	.set found, found+1\n"
-"	.long \\type + (regnr << 8)\n"
-"	.endif\n"
-"	.set regnr, regnr+1\n"
-"	.endr\n"
-"	.if (found != 1)\n"
-"	.error \"extable_type_reg: bad register argument\"\n"
-"	.endif\n"
+# define DEFINE_EXTABLE_TYPE_REG \
+"	.macro extable_type_reg type:req reg:req\n"						\
+"	.set found, 0\n"									\
+"	.set regnr, 0\n"									\
+"	.irp rs,rax,rcx,rdx,rbx,rsp,rbp,rsi,rdi,r8,r9,r10,r11,r12,r13,r14,r15\n"		\
+"	.ifc \\reg, %%\\rs\n"									\
+"	.set found, found+1\n"									\
+"	.long \\type + (regnr << 8)\n"								\
+"	.endif\n"										\
+"	.set regnr, regnr+1\n"									\
+"	.endr\n"										\
+"	.set regnr, 0\n"									\
+"	.irp rs,eax,ecx,edx,ebx,esp,ebp,esi,edi,r8d,r9d,r10d,r11d,r12d,r13d,r14d,r15d\n"	\
+"	.ifc \\reg, %%\\rs\n"									\
+"	.set found, found+1\n"									\
+"	.long \\type + (regnr << 8)\n"								\
+"	.endif\n"										\
+"	.set regnr, regnr+1\n"									\
+"	.endr\n"										\
+"	.if (found != 1)\n"									\
+"	.error \"extable_type_reg: bad register argument\"\n"					\
+"	.endif\n"										\
 "	.endm\n"
-);
+
+# define UNDEFINE_EXTABLE_TYPE_REG \
+"	.purgem extable_type_reg\n"
+
+# define __extable_type_reg(type, reg) \
+	DEFINE_EXTABLE_TYPE_REG								\
+"	extable_type_reg type=" __stringify(type) ", reg=" __stringify(reg) " \n"	\
+	UNDEFINE_EXTABLE_TYPE_REG
 
 # define _ASM_EXTABLE_TYPE(from, to, type)			\
 	" .pushsection \"__ex_table\",\"a\"\n"			\
@@ -185,12 +192,12 @@ asm(
 	" .long " __stringify(type) " \n"			\
 	" .popsection\n"
 
-# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg)				\
-	" .pushsection \"__ex_table\",\"a\"\n"					\
-	" .balign 4\n"								\
-	" .long (" #from ") - .\n"						\
-	" .long (" #to ") - .\n"						\
-	"extable_type_reg reg=" __stringify(reg) ", type=" __stringify(type) " \n"\
+# define _ASM_EXTABLE_TYPE_REG(from, to, type, reg)	\
+	" .pushsection \"__ex_table\",\"a\"\n"		\
+	" .balign 4\n"					\
+	" .long (" #from ") - .\n"			\
+	" .long (" #to ") - .\n"			\
+	__extable_type_reg(type, reg)			\
 	" .popsection\n"
 
 /* For C file, we already have NOKPROBE_SYMBOL macro */

@nathanchance
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Patch submitted: https://lore.kernel.org/r/[email protected]/

@nathanchance nathanchance added [BUG] linux-next This is an issue only seen in linux-next [PATCH] Submitted A patch has been submitted for review labels Dec 10, 2021
@nathanchance nathanchance self-assigned this Dec 10, 2021
@nathanchance
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Fixed: https://git.kernel.org/tip/4b5305decc8436bfe363d1c1773e8fa1c828b14d

@nathanchance nathanchance added [FIXED][LINUX] development cycle This bug was only present and fixed in a -next or -rc cycle and removed [PATCH] Submitted A patch has been submitted for review labels Dec 13, 2021
@nathanchance nathanchance mentioned this issue Mar 23, 2022
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[BUG] linux-next This is an issue only seen in linux-next [FEATURE] LTO Related to building the kernel with LLVM Link Time Optimization [FIXED][LINUX] development cycle This bug was only present and fixed in a -next or -rc cycle [Reported-by] kbuild test robot Reported-by: kbuild test robot <[email protected]> [TOOL] integrated-as The issue is relevant to LLVM integrated assembler
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