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kbuild: -ffunction-sections fix for archs with conflicting sections

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Enabling -ffunction-sections modified the generic linker script to
pull .text.* sections into regular TEXT_TEXT section, conflicting
with some architectures. Revert that change and require archs that
enable the option to ensure they have no conflicting section names,
and do the appropriate merging.

Reported-by: Guenter Roeck <linux@roeck-us.net>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: b67067f117 ("kbuild: allow archs to select link dead code/data elimination")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.com>
This commit is contained in:
Nicholas Piggin 2016-09-14 12:24:03 +10:00 committed by Michal Marek
parent fbe6e37dab
commit 0f4c4af06e
2 changed files with 13 additions and 6 deletions
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4
arch/Kconfig
View File

@ -478,7 +478,9 @@ config LD_DEAD_CODE_DATA_ELIMINATION
This requires that the arch annotates or otherwise protects
its external entry points from being discarded. Linker scripts
must also merge .text.*, .data.*, and .bss.* correctly into
output sections.
output sections. Care must be taken not to pull in unrelated
sections (e.g., '.text.init'). Typically '.' in section names
is used to distinguish them from label names / C identifiers.
config HAVE_CONTEXT_TRACKING
bool

15
include/asm-generic/vmlinux.lds.h
View File

@ -198,9 +198,9 @@
/*
* .data section
* -fdata-sections generates .data.identifier which needs to be pulled in
* with .data, but don't want to pull in .data..stuff which has its own
* requirements. Same for bss.
* LD_DEAD_CODE_DATA_ELIMINATION option enables -fdata-sections generates
* .data.identifier which needs to be pulled in with .data, but don't want to
* pull in .data..stuff which has its own requirements. Same for bss.
*/
#define DATA_DATA \
*(.data .data.[0-9a-zA-Z_]*) \
@ -434,10 +434,15 @@
}
/* .text section. Map to function alignment to avoid address changes
* during second ld run in second ld pass when generating System.map */
* during second ld run in second ld pass when generating System.map
* LD_DEAD_CODE_DATA_ELIMINATION option enables -ffunction-sections generates
* .text.identifier which needs to be pulled in with .text , but some
* architectures define .text.foo which is not intended to be pulled in here.
* Those enabling LD_DEAD_CODE_DATA_ELIMINATION must ensure they don't have
* conflicting section names, and must pull in .text.[0-9a-zA-Z_]* */
#define TEXT_TEXT \
ALIGN_FUNCTION(); \
*(.text.hot .text .text.fixup .text.unlikely .text.*) \
*(.text.hot .text .text.fixup .text.unlikely) \
*(.ref.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text) \