Messages in this thread Patch in this message | | | Date | Tue, 7 Jun 2022 17:59:56 -0700 | From | Josh Poimboeuf <> | Subject | Re: 5.19-rc1 x86 build failure |
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On Tue, Jun 07, 2022 at 12:42:33PM +0000, Andrew Cooper wrote: > On 07/06/2022 13:19, Joe Damato wrote: > > 96 .pushsection .brk_reservation,"aw",@nobits > > 97 .brk.early_pgt_alloc: > > 98 ???? 00000000 .skip ((2 * 3) * ((1UL) << 12)) > > **** Error: missing ')' > > **** Error: missing ')' > > **** Error: missing ')' > > **** Error: junk at end of line, first unrecognized character is `U' > > 98 0000 > > 100 .popsection > > > > This comes from arch/x86/mm/init.c, which has the following code: > > > > RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE); > > > > wherein INIT_PGT_BUF_SIZE (via PAGE_SIZE) has a "1UL" which makes the > > assembler unhappy. > > > > I don't really know what the correct way to fix this is; it seems that the > > macro _AC should handle this if ASSEMBLY is defined, IIUC, but that does > > not seem to be the case at this point in init.c. > > > > Perhaps I am doing something incorrect during the build process causing > > this to happen? > > The problem is that _AC() is evaluated in C context (so gains the UL/ULL > suffix), and the C'd string is fed directly into the assembler (where > older binutils doesn't tolerate the suffix). > > Short of having a _PAGE_SIZE which is an explicitly non-AC()'d constant, > I'm not sure what to suggest. Ideally, you'd want to temporarily define > __ASSEMBLY__ around the expansion of __stringify(), but I don't think > that's possible as RESERVE_BRK() is a macro itself.
Joe, what version of binutils do you have?
We can fix this by taking a completely different approach: define the variable in C and just do the "nobits" in the linker script, like below. I can work up a proper patch tomorrow.
diff --git a/arch/x86/include/asm/setup.h b/arch/x86/include/asm/setup.h index 7590ac2570b9..4704184a2d78 100644 --- a/arch/x86/include/asm/setup.h +++ b/arch/x86/include/asm/setup.h @@ -108,19 +108,11 @@ extern unsigned long _brk_end; void *extend_brk(size_t size, size_t align); /* - * Reserve space in the brk section. The name must be unique within the file, + * Reserve space in the .brk section. The name must be unique within vmlinux, * and somewhat descriptive. The size is in bytes. - * - * The allocation is done using inline asm (rather than using a section - * attribute on a normal variable) in order to allow the use of @nobits, so - * that it doesn't take up any space in the vmlinux file. */ #define RESERVE_BRK(name, size) \ - asm(".pushsection .brk_reservation,\"aw\",@nobits\n\t" \ - ".brk." #name ":\n\t" \ - ".skip " __stringify(size) "\n\t" \ - ".size .brk." #name ", " __stringify(size) "\n\t" \ - ".popsection\n\t") + char __brk_##name[size] __section(".brk_reservation"); extern void probe_roms(void); #ifdef __i386__ @@ -133,12 +125,16 @@ asmlinkage void __init x86_64_start_reservations(char *real_mode_data); #endif /* __i386__ */ #endif /* _SETUP */ -#else -#define RESERVE_BRK(name,sz) \ - .pushsection .brk_reservation,"aw",@nobits; \ -.brk.name: \ -1: .skip sz; \ - .size .brk.name,.-1b; \ + +#else /* __ASSEMBLY */ + +#define RESERVE_BRK(name, size) \ + .pushsection .brk_reservation, "aw"; \ +__brk_##name: \ +1: .skip size; \ + .size __brk_##name, . - 1b; \ .popsection + #endif /* __ASSEMBLY__ */ + #endif /* _ASM_X86_SETUP_H */ diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 91831b9d8aa8..f105b8aa055e 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -392,7 +392,7 @@ SECTIONS __end_of_kernel_reserve = .; . = ALIGN(PAGE_SIZE); - .brk : AT(ADDR(.brk) - LOAD_OFFSET) { + .brk (NOLOAD) : AT(ADDR(.brk) - LOAD_OFFSET) { __brk_base = .; . += 64 * 1024; /* 64k alignment slop space */ *(.brk_reservation) /* areas brk users have reserved */
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