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Use separate sections for __dev/__cpu/__mem code/data
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Introducing separate sections for __dev* (HOTPLUG),
__cpu* (HOTPLUG_CPU) and __mem* (MEMORY_HOTPLUG)
allows us to do a much more reliable Section mismatch
check in modpost. We are no longer dependent on the actual
configuration of for example HOTPLUG.

This has the effect that all users see much more
Section mismatch warnings than before because they
were almost all hidden when HOTPLUG was enabled.
The advantage of this is that when building a piece
of code then it is much more likely that the Section
mismatch errors are spotted and the warnings will be
felt less random of nature.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Adrian Bunk <bunk@kernel.org>
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Sam Ravnborg committed Jan 28, 2008
1 parent f3fe866 commit eb8f689
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Showing 3 changed files with 159 additions and 60 deletions.
88 changes: 82 additions & 6 deletions include/asm-generic/vmlinux.lds.h
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Original file line number Diff line number Diff line change
Expand Up @@ -9,10 +9,46 @@
/* Align . to a 8 byte boundary equals to maximum function alignment. */
#define ALIGN_FUNCTION() . = ALIGN(8)

/* The actual configuration determine if the init/exit sections
* are handled as text/data or they can be discarded (which
* often happens at runtime)
*/
#ifdef CONFIG_HOTPLUG
#define DEV_KEEP(sec) *(.dev##sec)
#define DEV_DISCARD(sec)
#else
#define DEV_KEEP(sec)
#define DEV_DISCARD(sec) *(.dev##sec)
#endif

#ifdef CONFIG_HOTPLUG_CPU
#define CPU_KEEP(sec) *(.cpu##sec)
#define CPU_DISCARD(sec)
#else
#define CPU_KEEP(sec)
#define CPU_DISCARD(sec) *(.cpu##sec)
#endif

#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
|| defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
#define MEM_KEEP(sec) *(.mem##sec)
#define MEM_DISCARD(sec)
#else
#define MEM_KEEP(sec)
#define MEM_DISCARD(sec) *(.mem##sec)
#endif


/* .data section */
#define DATA_DATA \
*(.data) \
*(.data.init.refok) \
DEV_KEEP(init.data) \
DEV_KEEP(exit.data) \
CPU_KEEP(init.data) \
CPU_KEEP(exit.data) \
MEM_KEEP(init.data) \
MEM_KEEP(exit.data) \
. = ALIGN(8); \
VMLINUX_SYMBOL(__start___markers) = .; \
*(__markers) \
Expand Down Expand Up @@ -132,14 +168,23 @@
*(__ksymtab_strings) \
} \
\
/* __*init sections */ \
__init_rodata : AT(ADDR(__init_rodata) - LOAD_OFFSET) { \
DEV_KEEP(init.rodata) \
DEV_KEEP(exit.rodata) \
CPU_KEEP(init.rodata) \
CPU_KEEP(exit.rodata) \
MEM_KEEP(init.rodata) \
MEM_KEEP(exit.rodata) \
} \
\
/* Built-in module parameters. */ \
__param : AT(ADDR(__param) - LOAD_OFFSET) { \
VMLINUX_SYMBOL(__start___param) = .; \
*(__param) \
VMLINUX_SYMBOL(__stop___param) = .; \
VMLINUX_SYMBOL(__end_rodata) = .; \
} \
\
. = ALIGN((align));

/* RODATA provided for backward compatibility.
Expand All @@ -159,7 +204,14 @@
ALIGN_FUNCTION(); \
*(.text) \
*(.text.init.refok) \
*(.exit.text.refok)
*(.exit.text.refok) \
DEV_KEEP(init.text) \
DEV_KEEP(exit.text) \
CPU_KEEP(init.text) \
CPU_KEEP(exit.text) \
MEM_KEEP(init.text) \
MEM_KEEP(exit.text)


/* sched.text is aling to function alignment to secure we have same
* address even at second ld pass when generating System.map */
Expand All @@ -184,11 +236,35 @@
VMLINUX_SYMBOL(__kprobes_text_end) = .;

/* init and exit section handling */
#define INIT_TEXT *(.init.text)
#define INIT_DATA *(.init.data)
#define EXIT_TEXT *(.exit.text)
#define EXIT_DATA *(.exit.data)
#define INIT_DATA \
*(.init.data) \
DEV_DISCARD(init.data) \
DEV_DISCARD(init.rodata) \
CPU_DISCARD(init.data) \
CPU_DISCARD(init.rodata) \
MEM_DISCARD(init.data) \
MEM_DISCARD(init.rodata)

#define INIT_TEXT \
*(.init.text) \
DEV_DISCARD(init.text) \
CPU_DISCARD(init.text) \
MEM_DISCARD(init.text)

#define EXIT_DATA \
*(.exit.data) \
DEV_DISCARD(exit.data) \
DEV_DISCARD(exit.rodata) \
CPU_DISCARD(exit.data) \
CPU_DISCARD(exit.rodata) \
MEM_DISCARD(exit.data) \
MEM_DISCARD(exit.rodata)

#define EXIT_TEXT \
*(.exit.text) \
DEV_DISCARD(exit.text) \
CPU_DISCARD(exit.text) \
MEM_DISCARD(exit.text)

/* DWARF debug sections.
Symbols in the DWARF debugging sections are relative to
Expand Down
77 changes: 38 additions & 39 deletions include/linux/init.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,18 +60,54 @@
#define __exit_refok noinline __section(.exit.text.refok)

#ifdef MODULE
#define __exit __section(.exit.text) __cold
#define __exitused
#else
#define __exit __attribute_used__ __section(.exit.text) __cold
#define __exitused __used
#endif

#define __exit __section(.exit.text) __exitused __cold

/* Used for HOTPLUG */
#define __devinit __section(.devinit.text) __cold
#define __devinitdata __section(.devinit.data)
#define __devinitconst __section(.devinit.rodata)
#define __devexit __section(.devexit.text) __exitused __cold
#define __devexitdata __section(.devexit.data)
#define __devexitconst __section(.devexit.rodata)

/* Used for HOTPLUG_CPU */
#define __cpuinit __section(.cpuinit.text) __cold
#define __cpuinitdata __section(.cpuinit.data)
#define __cpuinitconst __section(.cpuinit.rodata)
#define __cpuexit __section(.cpuexit.text) __exitused __cold
#define __cpuexitdata __section(.cpuexit.data)
#define __cpuexitconst __section(.cpuexit.rodata)

/* Used for MEMORY_HOTPLUG */
#define __meminit __section(.meminit.text) __cold
#define __meminitdata __section(.meminit.data)
#define __meminitconst __section(.meminit.rodata)
#define __memexit __section(.memexit.text) __exitused __cold
#define __memexitdata __section(.memexit.data)
#define __memexitconst __section(.memexit.rodata)

/* For assembly routines */
#define __INIT .section ".init.text","ax"
#define __INIT_REFOK .section ".text.init.refok","ax"
#define __FINIT .previous

#define __INITDATA .section ".init.data","aw"
#define __INITDATA_REFOK .section ".data.init.refok","aw"

#define __DEVINIT .section ".devinit.text", "ax"
#define __DEVINITDATA .section ".devinit.data", "aw"

#define __CPUINIT .section ".cpuinit.text", "ax"
#define __CPUINITDATA .section ".cpuinit.data", "aw"

#define __MEMINIT .section ".meminit.text", "ax"
#define __MEMINITDATA .section ".meminit.data", "aw"

#ifndef __ASSEMBLY__
/*
* Used for initialization calls..
Expand Down Expand Up @@ -254,43 +290,6 @@ void __init parse_early_param(void);
#define __initdata_or_module __initdata
#endif /*CONFIG_MODULES*/

#ifdef CONFIG_HOTPLUG
#define __devinit
#define __devinitdata
#define __devexit
#define __devexitdata
#else
#define __devinit __init
#define __devinitdata __initdata
#define __devexit __exit
#define __devexitdata __exitdata
#endif

#ifdef CONFIG_HOTPLUG_CPU
#define __cpuinit
#define __cpuinitdata
#define __cpuexit
#define __cpuexitdata
#else
#define __cpuinit __init
#define __cpuinitdata __initdata
#define __cpuexit __exit
#define __cpuexitdata __exitdata
#endif

#if defined(CONFIG_MEMORY_HOTPLUG) || defined(CONFIG_ACPI_HOTPLUG_MEMORY) \
|| defined(CONFIG_ACPI_HOTPLUG_MEMORY_MODULE)
#define __meminit
#define __meminitdata
#define __memexit
#define __memexitdata
#else
#define __meminit __init
#define __meminitdata __initdata
#define __memexit __exit
#define __memexitdata __exitdata
#endif

/* Functions marked as __devexit may be discarded at kernel link time, depending
on config options. Newer versions of binutils detect references from
retained sections to discarded sections and flag an error. Pointers to
Expand Down
54 changes: 39 additions & 15 deletions scripts/mod/modpost.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -670,27 +670,41 @@ int match(const char *sym, const char * const pat[])
static const char *section_white_list[] =
{ ".debug*", ".stab*", ".note*", ".got*", ".toc*", NULL };

#define INIT_DATA_SECTIONS ".init.data$"
#define EXIT_DATA_SECTIONS ".exit.data$"
#define ALL_INIT_DATA_SECTIONS \
".init.data$", ".devinit.data$", ".cpuinit.data$", ".meminit.data$"
#define ALL_EXIT_DATA_SECTIONS \
".exit.data$", ".devexit.data$", ".cpuexit.data$", ".memexit.data$"

#define INIT_TEXT_SECTIONS ".init.text$"
#define EXIT_TEXT_SECTIONS ".exit.text$"
#define ALL_INIT_TEXT_SECTIONS \
".init.text$", ".devinit.text$", ".cpuinit.text$", ".meminit.text$"
#define ALL_EXIT_TEXT_SECTIONS \
".exit.text$", ".devexit.text$", ".cpuexit.text$", ".memexit.text$"

#define INIT_SECTIONS INIT_DATA_SECTIONS, INIT_TEXT_SECTIONS
#define EXIT_SECTIONS EXIT_DATA_SECTIONS, EXIT_TEXT_SECTIONS
#define ALL_INIT_SECTIONS ALL_INIT_DATA_SECTIONS, ALL_INIT_TEXT_SECTIONS
#define ALL_EXIT_SECTIONS ALL_EXIT_DATA_SECTIONS, ALL_EXIT_TEXT_SECTIONS

#define DATA_SECTIONS ".data$", ".data.rel$"
#define TEXT_SECTIONS ".text$"

#define INIT_SECTIONS ".init.data$", ".init.text$"
#define DEV_INIT_SECTIONS ".devinit.data$", ".devinit.text$"
#define CPU_INIT_SECTIONS ".cpuinit.data$", ".cpuinit.text$"
#define MEM_INIT_SECTIONS ".meminit.data$", ".meminit.text$"

#define EXIT_SECTIONS ".exit.data$", ".exit.text$"
#define DEV_EXIT_SECTIONS ".devexit.data$", ".devexit.text$"
#define CPU_EXIT_SECTIONS ".cpuexit.data$", ".cpuexit.text$"
#define MEM_EXIT_SECTIONS ".memexit.data$", ".memexit.text$"

/* init data sections */
static const char *init_data_sections[] = { INIT_DATA_SECTIONS, NULL };
static const char *init_data_sections[] = { ALL_INIT_DATA_SECTIONS, NULL };

/* all init sections */
static const char *init_sections[] = { INIT_SECTIONS, NULL };
static const char *init_sections[] = { ALL_INIT_SECTIONS, NULL };

/* All init and exit sections (code + data) */
static const char *init_exit_sections[] =
{INIT_SECTIONS, EXIT_SECTIONS, NULL };
{ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL };

/* data section */
static const char *data_sections[] = { DATA_SECTIONS, NULL };
Expand Down Expand Up @@ -734,22 +748,32 @@ const struct sectioncheck sectioncheck[] = {
*/
{
.fromsec = { TEXT_SECTIONS, DATA_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL }
.tosec = { ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL }
},
/* Do not reference init code/data from devinit/cpuinit/meminit code/data */
{
.fromsec = { DEV_INIT_SECTIONS, CPU_INIT_SECTIONS, MEM_INIT_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, NULL }
},
/* Do not reference exit code/data from devexit/cpuexit/memexit code/data */
{
.fromsec = { DEV_EXIT_SECTIONS, CPU_EXIT_SECTIONS, MEM_EXIT_SECTIONS, NULL },
.tosec = { EXIT_SECTIONS, NULL }
},
/* Do not use exit code/data from init code */
{
.fromsec = { INIT_SECTIONS, NULL },
.tosec = { EXIT_SECTIONS, NULL },
.fromsec = { ALL_INIT_SECTIONS, NULL },
.tosec = { ALL_EXIT_SECTIONS, NULL },
},
/* Do not use init code/data from exit code */
{
.fromsec = { EXIT_SECTIONS, NULL },
.tosec = { INIT_SECTIONS, NULL }
.fromsec = { ALL_EXIT_SECTIONS, NULL },
.tosec = { ALL_INIT_SECTIONS, NULL }
},
/* Do not export init/exit functions or data */
{
.fromsec = { "__ksymtab*", NULL },
.tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL }
.tosec = { ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL }
}
};

Expand Down

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