From: Nick Desaulniers ndesaulniers@google.com
commit 334865b2915c33080624e0d06f1c3e917036472c upstream.
Bernardo reported an error that Nathan bisected down to (x86_64) defconfig+LTO_CLANG_FULL+X86_PMEM_LEGACY.
LTO vmlinux.o ld.lld: error: <instantiation>:1:13: redefinition of 'found' .set found, 0 ^
<inline asm>:29:1: while in macro instantiation extable_type_reg reg=%eax, type=(17 | ((0) << 16)) ^
This appears to be another LTO specific issue similar to what was folded into commit 4b5305decc84 ("x86/extable: Extend extable functionality"), where the `.set found, 0` in DEFINE_EXTABLE_TYPE_REG in arch/x86/include/asm/asm.h conflicts with the symbol for the static function `found` in arch/x86/kernel/pmem.c.
Assembler .set directive declare symbols with global visibility, so the assembler may not rename such symbols in the event of a conflict. LTO could rename static functions if there was a conflict in C sources, but it cannot see into symbols defined in inline asm.
The symbols are also retained in the symbol table, regardless of LTO.
Give the symbols .L prefixes making them locally visible, so that they may be renamed for LTO to avoid conflicts, and to drop them from the symbol table regardless of LTO.
Fixes: 4b5305decc84 ("x86/extable: Extend extable functionality") Reported-by: Bernardo Meurer Costa beme@google.com Debugged-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Reviewed-by: Nathan Chancellor nathan@kernel.org Tested-by: Nathan Chancellor nathan@kernel.org Link: https://lore.kernel.org/r/20220329202148.2379697-1-ndesaulniers@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/asm.h | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-)
--- a/arch/x86/include/asm/asm.h +++ b/arch/x86/include/asm/asm.h @@ -149,24 +149,24 @@
# define DEFINE_EXTABLE_TYPE_REG \ ".macro extable_type_reg type:req reg:req\n" \ - ".set found, 0\n" \ - ".set regnr, 0\n" \ + ".set .Lfound, 0\n" \ + ".set .Lregnr, 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" \ + ".set .Lfound, .Lfound+1\n" \ + ".long \type + (.Lregnr << 8)\n" \ ".endif\n" \ - ".set regnr, regnr+1\n" \ + ".set .Lregnr, .Lregnr+1\n" \ ".endr\n" \ - ".set regnr, 0\n" \ + ".set .Lregnr, 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" \ + ".set .Lfound, .Lfound+1\n" \ + ".long \type + (.Lregnr << 8)\n" \ ".endif\n" \ - ".set regnr, regnr+1\n" \ + ".set .Lregnr, .Lregnr+1\n" \ ".endr\n" \ - ".if (found != 1)\n" \ + ".if (.Lfound != 1)\n" \ ".error "extable_type_reg: bad register argument"\n" \ ".endif\n" \ ".endm\n"