* 5.19-rc1 x86 build failure
@ 2022-06-07 12:19 Joe Damato
2022-06-07 12:42 ` Andrew Cooper
0 siblings, 1 reply; 6+ messages in thread
From: Joe Damato @ 2022-06-07 12:19 UTC (permalink / raw)
To: x86
Cc: jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst,
Andrew.Cooper3
Greetings:
My apologies if this is the incorrect place to report this, but I got a
build error when trying to compile the net-next 5.19-rc1 tree.
git bisect says that commit a1e2c031ec394 ("x86/mm: Simplify
RESERVE_BRK()") is responsible for the build issue I am hitting.
I am performing this build on an x86_64 system with GNU C11 (Ubuntu
5.4.0-6ubuntu1~16.04.12) version 5.4.0 20160609 (x86_64-linux-gnu).
The assembler outputs a cryptic error message:
/tmp/ccnGOKZ5.s: Assembler messages:
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: missing ')'
/tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized
character is `U'
/tmp/ccnGOKZ5.s:99: Error: missing ')'
/tmp/ccnGOKZ5.s:99: Error: missing ')'
/tmp/ccnGOKZ5.s:99: Error: missing ')'
/tmp/ccnGOKZ5.s:99: Error: junk at end of line, first unrecognized
character is `U'
I've asked GCC to generate the assembly and output so I can see more
specifically where this issue is (via "-fverbose-asm -Wa,-adhln=output"):
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?
Thanks,
Joe
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: 5.19-rc1 x86 build failure 2022-06-07 12:19 5.19-rc1 x86 build failure Joe Damato @ 2022-06-07 12:42 ` Andrew Cooper 2022-06-08 0:59 ` Josh Poimboeuf 0 siblings, 1 reply; 6+ messages in thread From: Andrew Cooper @ 2022-06-07 12:42 UTC (permalink / raw) To: Joe Damato, x86 Cc: jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst, Andrew Cooper On 07/06/2022 13:19, Joe Damato wrote: > Greetings: > > My apologies if this is the incorrect place to report this, but I got a > build error when trying to compile the net-next 5.19-rc1 tree. > > git bisect says that commit a1e2c031ec394 ("x86/mm: Simplify > RESERVE_BRK()") is responsible for the build issue I am hitting. > > I am performing this build on an x86_64 system with GNU C11 (Ubuntu > 5.4.0-6ubuntu1~16.04.12) version 5.4.0 20160609 (x86_64-linux-gnu). > > The assembler outputs a cryptic error message: > > /tmp/ccnGOKZ5.s: Assembler messages: > /tmp/ccnGOKZ5.s:98: Error: missing ')' > /tmp/ccnGOKZ5.s:98: Error: missing ')' > /tmp/ccnGOKZ5.s:98: Error: missing ')' > /tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized > character is `U' > /tmp/ccnGOKZ5.s:99: Error: missing ')' > /tmp/ccnGOKZ5.s:99: Error: missing ')' > /tmp/ccnGOKZ5.s:99: Error: missing ')' > /tmp/ccnGOKZ5.s:99: Error: junk at end of line, first unrecognized > character is `U' > > I've asked GCC to generate the assembly and output so I can see more > specifically where this issue is (via "-fverbose-asm -Wa,-adhln=output"): > > 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. ~Andrew ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 5.19-rc1 x86 build failure 2022-06-07 12:42 ` Andrew Cooper @ 2022-06-08 0:59 ` Josh Poimboeuf 2022-06-08 9:10 ` Joe Damato 2022-06-08 9:24 ` Andrew Cooper 0 siblings, 2 replies; 6+ messages in thread From: Josh Poimboeuf @ 2022-06-08 0:59 UTC (permalink / raw) To: Andrew Cooper Cc: Joe Damato, x86, jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst 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 */ ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: 5.19-rc1 x86 build failure 2022-06-08 0:59 ` Josh Poimboeuf @ 2022-06-08 9:10 ` Joe Damato 2022-06-08 9:24 ` Andrew Cooper 1 sibling, 0 replies; 6+ messages in thread From: Joe Damato @ 2022-06-08 9:10 UTC (permalink / raw) To: Josh Poimboeuf Cc: Andrew Cooper, x86, jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst On Tue, Jun 07, 2022 at 05:59:56PM -0700, Josh Poimboeuf wrote: > 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? I am using binutils: 2.26.1-1ubuntu1~16.04.8+esm4. > 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. The change below makes sense to me. I applied it locally and was able to build the kernel again. Let me know if you'd like me to try building the next patch you write up. > 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 */ ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 5.19-rc1 x86 build failure 2022-06-08 0:59 ` Josh Poimboeuf 2022-06-08 9:10 ` Joe Damato @ 2022-06-08 9:24 ` Andrew Cooper 2022-06-08 15:00 ` Josh Poimboeuf 1 sibling, 1 reply; 6+ messages in thread From: Andrew Cooper @ 2022-06-08 9:24 UTC (permalink / raw) To: Josh Poimboeuf Cc: Joe Damato, x86, jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst, Andrew Cooper On 08/06/2022 01:59, Josh Poimboeuf wrote: > @@ -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 While I think about it before you write the patch properly, you ought to have a .type in here too, seeing as the C side now gets one. ~Andrew ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: 5.19-rc1 x86 build failure 2022-06-08 9:24 ` Andrew Cooper @ 2022-06-08 15:00 ` Josh Poimboeuf 0 siblings, 0 replies; 6+ messages in thread From: Josh Poimboeuf @ 2022-06-08 15:00 UTC (permalink / raw) To: Andrew Cooper Cc: Joe Damato, x86, jpoimboe, peterz, linux-kernel, jiangshanlai, bp, brgerst On Wed, Jun 08, 2022 at 09:24:25AM +0000, Andrew Cooper wrote: > On 08/06/2022 01:59, Josh Poimboeuf wrote: > > @@ -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 > > While I think about it before you write the patch properly, you ought to > have a .type in here too, seeing as the C side now gets one. Good point, I'll just use the SYM_DATA_{START,END} macros. -- Josh ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2022-06-08 15:10 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-06-07 12:19 5.19-rc1 x86 build failure Joe Damato 2022-06-07 12:42 ` Andrew Cooper 2022-06-08 0:59 ` Josh Poimboeuf 2022-06-08 9:10 ` Joe Damato 2022-06-08 9:24 ` Andrew Cooper 2022-06-08 15:00 ` Josh Poimboeuf
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