kbuild: protect compiled-in dtb from dead data elimination
PATCH 1/1 kbuild: protect compiled-in dtb from dead data elimination
DTBs are compiled into byte arrays that are placed inside .dtb.init.rodata section. As they are never referenced directly from the code, they get removed during dead data elimination and we end up with __dtb_start == __dtb_end.
--- include/asm-generic/vmlinux.lds.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
include/asm-generic/vmlinux.lds.h +1 -1
@@ -193,7 +193,7 @@#define KERNEL_DTB () \ STRUCT_ALIGN(); \ VMLINUX_SYMBOL(__dtb_start) = .; \ - *(.dtb.init.rodata) \ + KEEP(*(.dtb.init.rodata)) \ VMLINUX_SYMBOL(__dtb_end) = .;/*
Signature · 1 line
2.7.4
Quoted 4 lines · On Wed, 26 Oct 2016 10:47:43 +0200 Marcin Nowakowski…
DTBs are compiled into byte arrays that are placed inside .dtb.init.rodata section. As they are never referenced directly from the code, they get removed during dead data elimination and we end up with
__dtb_start==__dtb_end.
Thanks, I got a bunch of patches from Paul for similar, so I went through it and we've actually got a lot of tables we should probably protect with KEEP(). For reference this is what I have on top of Paul's patches. I'll send them up to kbuild after we get this CRC build issue dealt with.
I'm glad you guys are finding it useful.
Thanks,
Nick
From: Nicholas Piggin <[email protected]>
Date: Tue, 25 Oct 2016 20:42:42 +1100
Subject: [PATCH] kbuild: dead code elimination keep various other tables
This should get a little bit less painful as things eventually move to generic linker table helper macros, but for now be liberal in keeping data tables.
--- include/asm-generic/vmlinux.lds.h | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-)
include/asm-generic/vmlinux.lds.h +16 -16
@@ -184,7 +184,7 @@#define ACPI_PROBE_TABLE (name) \ . = ALIGN(8); \ VMLINUX_SYMBOL(__##name##_acpi_probe_table) = .; \ - *(__##name##_acpi_probe_table) \ + KEEP(*(__##name##_acpi_probe_table)) \ VMLINUX_SYMBOL(__##name##_acpi_probe_table_end) = .;#else #define ACPI_PROBE_TABLE (name)
@@ -193,7 +193,7 @@#define KERNEL_DTB () \ STRUCT_ALIGN(); \ VMLINUX_SYMBOL(__dtb_start) = .; \ - *(.dtb.init.rodata) \ + KEEP(*(.dtb.init.rodata)) \ VMLINUX_SYMBOL(__dtb_end) = .;/*
@@ -214,11 +214,11 @@/* implement dynamic printk debug */ \ . = ALIGN(8); \ VMLINUX_SYMBOL(__start___jump_table) = .; \ - *(__jump_table ) \ + KEEP(*(__jump_table)) \ VMLINUX_SYMBOL(__stop___jump_table) = .; \ . = ALIGN(8); \ VMLINUX_SYMBOL(__start___verbose) = .; \ - *(__verbose ) \ + KEEP(*(__verbose)) \ VMLINUX_SYMBOL(__stop___verbose) = .; \ LIKELY_PROFILE() \BRANCH_PROFILE () \
@@ -271,10 +271,10 @@ VMLINUX_SYMBOL(__start_rodata) = .; \ *(.rodata) *(.rodata.*) \ RO_AFTER_INIT_DATA /* Read only after init */ \ - *(__vermagic) /* Kernel version magic */ \ +KEEP (*(__vermagic))/* Kernel version magic */ \ . = ALIGN(8); \ VMLINUX_SYMBOL(__start___tracepoints_ptrs) = .; \ - *(__tracepoints_ptrs) /* Tracepoints: pointer array */\ + KEEP(*(__tracepoints_ptrs)) /* Tracepoints: pointer array */ \ VMLINUX_SYMBOL(__stop___tracepoints_ptrs) = .; \ *(__tracepoints_strings)/* Tracepoints: strings */ \ } \
@@ -316,7 +316,7 @@/* Built-in firmware blobs */ \ .builtin_fw : AT(ADDR(.builtin_fw) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start_builtin_fw) = .; \ - *(.builtin_fw) \ + KEEP(*(.builtin_fw)) \ VMLINUX_SYMBOL(__end_builtin_fw) = .; \ } \ \
@@ -394,7 +394,7 @@ \/* Kernel symbol table: strings */ \ __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) { \ - KEEP(*(__ksymtab_strings)) \ + *(__ksymtab_strings) \ } \ \/* __*init sections */ \
@@ -407,14 +407,14 @@/* Built-in module parameters. */ \ __param : AT(ADDR(__param) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___param) = .; \ - *(__param ) \ + KEEP(*(__param)) \ VMLINUX_SYMBOL(__stop___param) = .; \ } \ \/* Built-in module versions. */ \ __modver : AT(ADDR(__modver) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___modver) = .; \ - *(__modver ) \ + KEEP(*(__modver)) \ VMLINUX_SYMBOL(__stop___modver) = .; \ . = ALIGN((align)); \ VMLINUX_SYMBOL(__end_rodata) = .; \
@@ -517,7 +517,7 @@ . = ALIGN(align); \ __ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___ex_table) = .; \ - *(__ex_table ) \ + KEEP(*(__ex_table)) \ VMLINUX_SYMBOL(__stop___ex_table) = .; \ }
@@ -533,9 +533,9 @@#ifdef CONFIG_CONSTRUCTORS #define KERNEL_CTORS () . = ALIGN(8); \ VMLINUX_SYMBOL(__ctors_start) = .; \ - *(.ctors) \ - *(SORT(.init_array.*)) \ - *(.init_array) \ + KEEP(*(.ctors)) \ + KEEP(*(SORT(.init_array.*))) \ + KEEP(*(.init_array)) \ VMLINUX_SYMBOL(__ctors_end) = .;#else #define KERNEL_CTORS ()
@@ -659,7 +659,7 @@ . = ALIGN(8); \ __bug_table : AT(ADDR(__bug_table) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start___bug_table) = .; \ - *(__bug_table ) \ + KEEP(*(__bug_table)) \ VMLINUX_SYMBOL(__stop___bug_table) = .; \ }#else
@@ -671,7 +671,7 @@ . = ALIGN(4); \ .tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__tracedata_start) = .; \ - *(.tracedata) \ + KEEP(*(.tracedata)) \ VMLINUX_SYMBOL(__tracedata_end) = .; \ } #else
Signature · 1 line
2.9.3