* [PATCH] kbuild: protect compiled-in dtb from dead data elimination
@ 2016-10-26 8:47 Marcin Nowakowski
2016-10-26 8:53 ` Nicholas Piggin
0 siblings, 1 reply; 2+ messages in thread
From: Marcin Nowakowski @ 2016-10-26 8:47 UTC (permalink / raw)
To: linux-kernel; +Cc: npiggin, mmarek, 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.
Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Fixes: b67067f1176d ("kbuild: allow archs to select link dead code/data elimination"
---
include/asm-generic/vmlinux.lds.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index abe79e3..ad5d0bb 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -193,7 +193,7 @@
#define KERNEL_DTB() \
STRUCT_ALIGN(); \
VMLINUX_SYMBOL(__dtb_start) = .; \
- *(.dtb.init.rodata) \
+ KEEP(*(.dtb.init.rodata)) \
VMLINUX_SYMBOL(__dtb_end) = .;
/*
--
2.7.4
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [PATCH] kbuild: protect compiled-in dtb from dead data elimination
2016-10-26 8:47 [PATCH] kbuild: protect compiled-in dtb from dead data elimination Marcin Nowakowski
@ 2016-10-26 8:53 ` Nicholas Piggin
0 siblings, 0 replies; 2+ messages in thread
From: Nicholas Piggin @ 2016-10-26 8:53 UTC (permalink / raw)
To: Marcin Nowakowski; +Cc: linux-kernel, mmarek, Paul Burton, linux-kbuid
On Wed, 26 Oct 2016 10:47:43 +0200
Marcin Nowakowski <marcin.nowakowski@imgtec.com> wrote:
> 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 <npiggin@gmail.com>
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.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
include/asm-generic/vmlinux.lds.h | 32 ++++++++++++++++----------------
1 file changed, 16 insertions(+), 16 deletions(-)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index abe79e3..1cac167 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -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
--
2.9.3
^ permalink raw reply [flat|nested] 2+ messages in thread
end of thread, other threads:[~2016-10-26 8:53 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-10-26 8:47 [PATCH] kbuild: protect compiled-in dtb from dead data elimination Marcin Nowakowski
2016-10-26 8:53 ` Nicholas Piggin
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
Powered by JetHome