Messages in this thread Patch in this message | | | Date | Tue, 5 May 2009 18:39:30 +0200 | From | Sam Ravnborg <> | Subject | Re: [PATCH] x86-64: fix build with older binutils |
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Hi Jan.
> Impact: build fix > > binutils prior to 2.17 can't deal with the currently possible situation > of a new segment following the per-CPU segment, but that new segment > being empty - objcopy misplaces the .bss (and perhaps also the .brk) > sections outside of any segment. However, the current ordering of > sections really just appears to be the effect of cumulative unrelated > changes; re-ordering things allows to easily guarantee that the segment > following the per-CPU one is non-empty, and at once eliminates the need > for the bogus data.init2 segment. > > Signed-off-by: Jan Beulich <jbeulich@novell.com>
I like the way your patch simplies the linker scrip for x86. We have recently merged the linker scripts for 32 and 64 bit, and I tried to apply your patch on top of the unified version. (Applied manually obviously).
With a 64 bit defconfig build I got: /home/sam/x-tools/x86_64-unknown-linux-gnu/bin/x86_64-unknown-linux-gnu-ld: section .vsyscall_0 [00000000016c6000 -> 00000000016c60e7] overlaps section .init.rodata [00000000016c5a00 -> 00000000016c6348] make[1]: *** [.tmp_vmlinux1] Error 1
I did not try to build a kernel with your original patch.
Can you spot anything obvious wrong in my patch. It is on top of x86/kbuild in -tip.
Sam
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S index 4c85b2e..477fa48 100644 --- a/arch/x86/kernel/vmlinux.lds.S +++ b/arch/x86/kernel/vmlinux.lds.S @@ -46,11 +46,10 @@ PHDRS { data PT_LOAD FLAGS(7); /* RWE */ #ifdef CONFIG_X86_64 user PT_LOAD FLAGS(7); /* RWE */ - data.init PT_LOAD FLAGS(7); /* RWE */ #ifdef CONFIG_SMP percpu PT_LOAD FLAGS(7); /* RWE */ #endif - data.init2 PT_LOAD FLAGS(7); /* RWE */ + init PT_LOAD FLAGS(7); /* RWE */ #endif note PT_NOTE FLAGS(0); /* ___ */ } @@ -103,70 +102,58 @@ SECTIONS __stop___ex_table = .; } :text = 0x9090 - RODATA + RO_DATA(PAGE_SIZE) /* Data */ . = ALIGN(PAGE_SIZE); .data : AT(ADDR(.data) - LOAD_OFFSET) { - DATA_DATA - CONSTRUCTORS - -#ifdef CONFIG_X86_64 - /* End of data section */ - _edata = .; -#endif - } :data + /* init_task */ + . = ALIGN(THREAD_SIZE); + *(.data.init_task) -#ifdef CONFIG_X86_32 - /* 32 bit has nosave before _edata */ - . = ALIGN(PAGE_SIZE); - .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { - __nosave_begin = .; - *(.data.nosave) . = ALIGN(PAGE_SIZE); - __nosave_end = .; - } -#endif - - . = ALIGN(PAGE_SIZE); - .data.page_aligned : AT(ADDR(.data.page_aligned) - LOAD_OFFSET) { *(.data.page_aligned) - *(.data.idt) - } #ifdef CONFIG_X86_32 - . = ALIGN(32); + . = ALIGN(32); #else - . = ALIGN(PAGE_SIZE); - . = ALIGN(CONFIG_X86_L1_CACHE_BYTES); + . = ALIGN(CONFIG_X86_L1_CACHE_BYTES); #endif - .data.cacheline_aligned : - AT(ADDR(.data.cacheline_aligned) - LOAD_OFFSET) { *(.data.cacheline_aligned) - } - /* rarely changed data like cpu maps */ + DATA_DATA + CONSTRUCTORS + + /* rarely changed data like cpu maps */ #ifdef CONFIG_X86_32 - . = ALIGN(32); + . = ALIGN(32); #else - . = ALIGN(CONFIG_X86_INTERNODE_CACHE_BYTES); + . = ALIGN(CONFIG_X86_INTERNODE_CACHE_BYTES); #endif - .data.read_mostly : AT(ADDR(.data.read_mostly) - LOAD_OFFSET) { *(.data.read_mostly) -#ifdef CONFIG_X86_32 /* End of data section */ _edata = .; -#endif + } :data + +#ifdef CONFIG_X86_32 + /* 32 bit has nosave before _edata */ + . = ALIGN(PAGE_SIZE); + .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { + __nosave_begin = .; + *(.data.nosave) + . = ALIGN(PAGE_SIZE); + __nosave_end = .; } +#endif #ifdef CONFIG_X86_64 #define VSYSCALL_ADDR (-10*1024*1024) -#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data.read_mostly) + \ - SIZEOF(.data.read_mostly) + 4095) & ~(4095)) -#define VSYSCALL_VIRT_ADDR ((ADDR(.data.read_mostly) + \ - SIZEOF(.data.read_mostly) + 4095) & ~(4095)) +#define VSYSCALL_PHYS_ADDR ((LOADADDR(.data) + \ + SIZEOF(.data) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1)) +#define VSYSCALL_VIRT_ADDR ((ADDR(.data) + \ + SIZEOF(.data) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1)) #define VLOAD_OFFSET (VSYSCALL_ADDR - VSYSCALL_PHYS_ADDR) #define VLOAD(x) (ADDR(x) - VLOAD_OFFSET) @@ -232,35 +219,31 @@ SECTIONS #endif /* CONFIG_X86_64 */ - /* init_task */ - . = ALIGN(THREAD_SIZE); - .data.init_task : AT(ADDR(.data.init_task) - LOAD_OFFSET) { - *(.data.init_task) + /* will be freed after init - paired with __init_end */ + .init.start : AT(ADDR(.init.start) - LOAD_OFFSET) { + . = ALIGN(PAGE_SIZE); + __init_begin = .; } -#ifdef CONFIG_X86_64 - :data.init -#endif +#if defined(CONFIG_X86_64) && defined(CONFIG_SMP) /* - * smp_locks might be freed after init - * start/end must be page aligned + * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the + * output PHDR, so the next output section - .init.text - should + * start another segment - init. */ . = ALIGN(PAGE_SIZE); - .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) { - __smp_locks = .; - *(.smp_locks) - __smp_locks_end = .; - . = ALIGN(PAGE_SIZE); - } + PERCPU_VADDR(0, :percpu) +#endif - /* Init code and data - will be freed after init */ - . = ALIGN(PAGE_SIZE); .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) { - __init_begin = .; /* paired with __init_end */ _sinittext = .; INIT_TEXT _einittext = .; } +#ifdef CONFIG_X86_64 + :init +#endif + .init.data : AT(ADDR(.init.data) - LOAD_OFFSET) { INIT_DATA @@ -331,17 +314,7 @@ SECTIONS } #endif -#if defined(CONFIG_X86_64) && defined(CONFIG_SMP) - /* - * percpu offsets are zero-based on SMP. PERCPU_VADDR() changes the - * output PHDR, so the next output section - __data_nosave - should - * start another section data.init2. Also, pda should be at the head of - * percpu area. Preallocate it and define the percpu offset symbol - * so that it can be accessed as a percpu variable. - */ - . = ALIGN(PAGE_SIZE); - PERCPU_VADDR(0, :percpu) -#else +#if defined(CONFIG_X86_32) || !defined(CONFIG_SMP) PERCPU(PAGE_SIZE) #endif @@ -352,6 +325,18 @@ SECTIONS __init_end = .; } + /* + * smp_locks might be freed after init + * start/end must be page aligned + */ + . = ALIGN(PAGE_SIZE); + .smp_locks : AT(ADDR(.smp_locks) - LOAD_OFFSET) { + __smp_locks = .; + *(.smp_locks) + __smp_locks_end = .; + . = ALIGN(PAGE_SIZE); + } + #ifdef CONFIG_X86_64 .data_nosave : AT(ADDR(.data_nosave) - LOAD_OFFSET) { . = ALIGN(PAGE_SIZE); @@ -359,8 +344,7 @@ SECTIONS *(.data.nosave) . = ALIGN(PAGE_SIZE); __nosave_end = .; - } :data.init2 - /* use another section data.init2, see PERCPU_VADDR() above */ + } #endif /* BSS */
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