Messages in this thread Patch in this message | | | Date | Tue, 19 Dec 2006 10:46:29 +0530 | From | Vivek Goyal <> | Subject | [PATCH 3/5] i386: move startup_32() in text.head section |
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o Entry startup_32 was in .text section but it was accessing some init data too and it prompts MODPOST to generate compilation warnings.
WARNING: vmlinux - Section mismatch: reference to .init.data:boot_params from .text between '_text' (at offset 0xc0100029) and 'startup_32_smp' WARNING: vmlinux - Section mismatch: reference to .init.data:boot_params from .text between '_text' (at offset 0xc0100037) and 'startup_32_smp' WARNING: vmlinux - Section mismatch: reference to .init.data:init_pg_tables_end from .text between '_text' (at offset 0xc0100099) and 'startup_32_smp'
o Can't move startup_32 to .init.text as this entry point has to be at the start of bzImage. Hence moved startup_32 to a new section .text.head and instructed MODPOST to not to generate warnings if init data is being accessed from .text.head section. This code has been audited.
o SMP boot up code (startup_32_smp) can go into .init.text if CPU hotplug is not supported. Otherwise it generates more warnings
WARNING: vmlinux - Section mismatch: reference to .init.data:new_cpu_data from .text between 'checkCPUtype' (at offset 0xc0100126) and 'is486' WARNING: vmlinux - Section mismatch: reference to .init.data:new_cpu_data from .text between 'checkCPUtype' (at offset 0xc0100130) and 'is486'
Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> ---
arch/i386/kernel/head.S | 17 ++++++++++++++--- arch/i386/kernel/vmlinux.lds.S | 7 ++++++- scripts/mod/modpost.c | 10 +++++++++- 3 files changed, 29 insertions(+), 5 deletions(-)
diff -puN arch/i386/kernel/head.S~i386-reloc-kernel-move-startup_32-in-text-head arch/i386/kernel/head.S --- linux-2.6.19-rc1-reloc/arch/i386/kernel/head.S~i386-reloc-kernel-move-startup_32-in-text-head 2006-12-15 14:09:01.000000000 +0530 +++ linux-2.6.19-rc1-reloc-root/arch/i386/kernel/head.S 2006-12-15 14:09:01.000000000 +0530 @@ -53,6 +53,7 @@ * any particular GDT layout, because we load our own as soon as we * can. */ +.section .text.head ENTRY(startup_32) #ifdef CONFIG_PARAVIRT @@ -141,16 +142,25 @@ page_pde_offset = (__PAGE_OFFSET >> 20); jb 10b movl %edi,(init_pg_tables_end - __PAGE_OFFSET) -#ifdef CONFIG_SMP xorl %ebx,%ebx /* This is the boot CPU (BSP) */ jmp 3f - /* * Non-boot CPU entry point; entered from trampoline.S * We can't lgdt here, because lgdt itself uses a data segment, but * we know the trampoline has already loaded the boot_gdt_table GDT * for us. + * + * If cpu hotplug is not supported then this code can go in init section + * which will be freed later */ + +#ifdef CONFIG_HOTPLUG_CPU +.section .text +#else +.section .init.text +#endif + +#ifdef CONFIG_SMP ENTRY(startup_32_smp) cld movl $(__BOOT_DS),%eax @@ -208,8 +218,8 @@ ENTRY(startup_32_smp) xorl %ebx,%ebx incl %ebx -3: #endif /* CONFIG_SMP */ +3: /* * Enable paging @@ -492,6 +502,7 @@ ignore_int: #endif iret +.section .text #ifdef CONFIG_PARAVIRT startup_paravirt: cld diff -puN arch/i386/kernel/vmlinux.lds.S~i386-reloc-kernel-move-startup_32-in-text-head arch/i386/kernel/vmlinux.lds.S --- linux-2.6.19-rc1-reloc/arch/i386/kernel/vmlinux.lds.S~i386-reloc-kernel-move-startup_32-in-text-head 2006-12-15 14:09:01.000000000 +0530 +++ linux-2.6.19-rc1-reloc-root/arch/i386/kernel/vmlinux.lds.S 2006-12-15 14:09:01.000000000 +0530 @@ -37,9 +37,14 @@ SECTIONS { . = LOAD_OFFSET + LOAD_PHYSICAL_ADDR; phys_startup_32 = startup_32 - LOAD_OFFSET; + + .text.head : AT(ADDR(.text.head) - LOAD_OFFSET) { + _text = .; /* Text and read-only data */ + *(.text.head) + } :text = 0x9090 + /* read-only */ .text : AT(ADDR(.text) - LOAD_OFFSET) { - _text = .; /* Text and read-only data */ *(.text) SCHED_TEXT LOCK_TEXT diff -puN scripts/mod/modpost.c~i386-reloc-kernel-move-startup_32-in-text-head scripts/mod/modpost.c --- linux-2.6.19-rc1-reloc/scripts/mod/modpost.c~i386-reloc-kernel-move-startup_32-in-text-head 2006-12-15 14:09:01.000000000 +0530 +++ linux-2.6.19-rc1-reloc-root/scripts/mod/modpost.c 2006-12-15 14:09:01.000000000 +0530 @@ -623,11 +623,19 @@ static int secref_whitelist(const char * if (f1 && f2) return 1; - /* Whitelist all references from .pci_fixup section if vmlinux */ + /* Whitelist all references from .pci_fixup section if vmlinux + * Whitelist all refereces from .text.head to .init.data if vmlinux + * Whitelist all refereces from .text.head to .init.text if vmlinux + */ if (is_vmlinux(modname)) { if ((strcmp(fromsec, ".pci_fixup") == 0) && (strcmp(tosec, ".init.text") == 0)) return 1; + + if ((strcmp(fromsec, ".text.head") == 0) && + ((strcmp(tosec, ".init.data") == 0) || + (strcmp(tosec, ".init.text") == 0))) + return 1; } return 0; } _ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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