Re: [PATCH v2] mips: delete __cpuinit/__CPUINIT usage from MIPS code

[Ralf Baechle <ralf@linux-mips.org>]

On Wed, Jun 19, 2013 at 08:28:07PM -0400, Paul Gortmaker wrote:

> I am literally in the middle of typing up a mail to linux-arch that
> explains this, and that the no-op step comes in at the beginning of the
> merge window, and that the big purge comes at the end.
> 
> However, I do not want that process to be set in stone ; as Ralf indicated,
> he expected some changes to the mips tree and wanted to deal with the
> conflicts himself (which is fine by me!) and so we can do that at the
> expense of some temporary section warnings.  This is why I explicitly
> called them out in the above commit log.
> 
> > Once that is working, we would make a second pass and remove the
> > symbols themselves.
> 
> Yep, thanks for looking at things; it sounds like we are in alignment
> with how to proceed here -- only that I wasn't quick enough in getting
> the steps published and the no-op phase into linux-next.

And I having come to the same conclusion have spent the last few hours
running a test build with the following patch applied.  It does

 - make __cpuinit, __cpuinitdata, __cpuinitconst, __cpuexit, __cpuexitdata
   and __cpuexitconst nops.
 - with .cpuinit.* and .cpuexit.* sections now being unused support for
   these sections in linker scripts and modpost is no longer required.

  Ralf

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

 include/asm-generic/vmlinux.lds.h | 20 ---------------
 include/linux/init.h              | 18 +++++++-------
 scripts/mod/modpost.c             | 52 +++++++--------------------------------
 3 files changed, 18 insertions(+), 72 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index eb58d2d..eab362e 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -76,14 +76,6 @@
 #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)
 #define MEM_KEEP(sec)    *(.mem##sec)
 #define MEM_DISCARD(sec)
@@ -184,8 +176,6 @@
 	*(.data..shared_aligned) /* percpu related */			\
 	DEV_KEEP(init.data)						\
 	DEV_KEEP(exit.data)						\
-	CPU_KEEP(init.data)						\
-	CPU_KEEP(exit.data)						\
 	MEM_KEEP(init.data)						\
 	MEM_KEEP(exit.data)						\
 	*(.data.unlikely)						\
@@ -374,8 +364,6 @@
 		*(.ref.rodata)						\
 		DEV_KEEP(init.rodata)					\
 		DEV_KEEP(exit.rodata)					\
-		CPU_KEEP(init.rodata)					\
-		CPU_KEEP(exit.rodata)					\
 		MEM_KEEP(init.rodata)					\
 		MEM_KEEP(exit.rodata)					\
 	}								\
@@ -418,8 +406,6 @@
 		*(.ref.text)						\
 	DEV_KEEP(init.text)						\
 	DEV_KEEP(exit.text)						\
-	CPU_KEEP(init.text)						\
-	CPU_KEEP(exit.text)						\
 	MEM_KEEP(init.text)						\
 	MEM_KEEP(exit.text)						\
 		*(.text.unlikely)
@@ -504,7 +490,6 @@
 #define INIT_DATA							\
 	*(.init.data)							\
 	DEV_DISCARD(init.data)						\
-	CPU_DISCARD(init.data)						\
 	MEM_DISCARD(init.data)						\
 	KERNEL_CTORS()							\
 	MCOUNT_REC()							\
@@ -512,7 +497,6 @@
 	FTRACE_EVENTS()							\
 	TRACE_SYSCALLS()						\
 	DEV_DISCARD(init.rodata)					\
-	CPU_DISCARD(init.rodata)					\
 	MEM_DISCARD(init.rodata)					\
 	CLK_OF_TABLES()							\
 	CLKSRC_OF_TABLES()						\
@@ -522,22 +506,18 @@
 #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)
 
 #define EXIT_CALL							\
diff --git a/include/linux/init.h b/include/linux/init.h
index 8618147..a4eefc1 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -94,12 +94,12 @@
 #define __exit          __section(.exit.text) __exitused __cold notrace
 
 /* Used for HOTPLUG_CPU */
-#define __cpuinit        __section(.cpuinit.text) __cold notrace
-#define __cpuinitdata    __section(.cpuinit.data)
-#define __cpuinitconst   __constsection(.cpuinit.rodata)
-#define __cpuexit        __section(.cpuexit.text) __exitused __cold notrace
-#define __cpuexitdata    __section(.cpuexit.data)
-#define __cpuexitconst   __constsection(.cpuexit.rodata)
+#define __cpuinit
+#define __cpuinitdata
+#define __cpuinitconst
+#define __cpuexit
+#define __cpuexitdata
+#define __cpuexitconst
 
 /* Used for MEMORY_HOTPLUG */
 #define __meminit        __section(.meminit.text) __cold notrace
@@ -118,9 +118,9 @@
 #define __INITRODATA	.section	".init.rodata","a",%progbits
 #define __FINITDATA	.previous
 
-#define __CPUINIT        .section	".cpuinit.text", "ax"
-#define __CPUINITDATA    .section	".cpuinit.data", "aw"
-#define __CPUINITRODATA  .section	".cpuinit.rodata", "a"
+#define __CPUINIT
+#define __CPUINITDATA
+#define __CPUINITRODATA
 
 #define __MEMINIT        .section	".meminit.text", "ax"
 #define __MEMINITDATA    .section	".meminit.data", "aw"
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index a4be8e1..3acbf080 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -861,24 +861,23 @@ static void check_section(const char *modname, struct elf_info *elf,
 
 
 #define ALL_INIT_DATA_SECTIONS \
-	".init.setup$", ".init.rodata$", \
-	".cpuinit.rodata$", ".meminit.rodata$", \
-	".init.data$", ".cpuinit.data$", ".meminit.data$"
+	".init.setup$", ".init.rodata$", ".meminit.rodata$", \
+	".init.data$", ".meminit.data$"
 #define ALL_EXIT_DATA_SECTIONS \
-	".exit.data$", ".cpuexit.data$", ".memexit.data$"
+	".exit.data$", ".memexit.data$"
 
 #define ALL_INIT_TEXT_SECTIONS \
-	".init.text$", ".cpuinit.text$", ".meminit.text$"
+	".init.text$", ".meminit.text$"
 #define ALL_EXIT_TEXT_SECTIONS \
-	".exit.text$", ".cpuexit.text$", ".memexit.text$"
+	".exit.text$", ".memexit.text$"
 
 #define ALL_PCI_INIT_SECTIONS	\
 	".pci_fixup_early$", ".pci_fixup_header$", ".pci_fixup_final$", \
 	".pci_fixup_enable$", ".pci_fixup_resume$", \
 	".pci_fixup_resume_early$", ".pci_fixup_suspend$"
 
-#define ALL_XXXINIT_SECTIONS CPU_INIT_SECTIONS, MEM_INIT_SECTIONS
-#define ALL_XXXEXIT_SECTIONS CPU_EXIT_SECTIONS, MEM_EXIT_SECTIONS
+#define ALL_XXXINIT_SECTIONS MEM_INIT_SECTIONS
+#define ALL_XXXEXIT_SECTIONS MEM_EXIT_SECTIONS
 
 #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
 #define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS
@@ -887,11 +886,9 @@ static void check_section(const char *modname, struct elf_info *elf,
 #define TEXT_SECTIONS ".text$"
 
 #define INIT_SECTIONS      ".init.*"
-#define CPU_INIT_SECTIONS  ".cpuinit.*"
 #define MEM_INIT_SECTIONS  ".meminit.*"
 
 #define EXIT_SECTIONS      ".exit.*"
-#define CPU_EXIT_SECTIONS  ".cpuexit.*"
 #define MEM_EXIT_SECTIONS  ".memexit.*"
 
 /* init data sections */
@@ -979,48 +976,20 @@ const struct sectioncheck sectioncheck[] = {
 	.mismatch = DATA_TO_ANY_EXIT,
 	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
 },
-/* Do not reference init code/data from cpuinit/meminit code/data */
+/* Do not reference init code/data from meminit code/data */
 {
 	.fromsec = { ALL_XXXINIT_SECTIONS, NULL },
 	.tosec   = { INIT_SECTIONS, NULL },
 	.mismatch = XXXINIT_TO_SOME_INIT,
 	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
 },
-/* Do not reference cpuinit code/data from meminit code/data */
-{
-	.fromsec = { MEM_INIT_SECTIONS, NULL },
-	.tosec   = { CPU_INIT_SECTIONS, NULL },
-	.mismatch = XXXINIT_TO_SOME_INIT,
-	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
-},
-/* Do not reference meminit code/data from cpuinit code/data */
-{
-	.fromsec = { CPU_INIT_SECTIONS, NULL },
-	.tosec   = { MEM_INIT_SECTIONS, NULL },
-	.mismatch = XXXINIT_TO_SOME_INIT,
-	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
-},
-/* Do not reference exit code/data from cpuexit/memexit code/data */
+/* Do not reference exit code/data from memexit code/data */
 {
 	.fromsec = { ALL_XXXEXIT_SECTIONS, NULL },
 	.tosec   = { EXIT_SECTIONS, NULL },
 	.mismatch = XXXEXIT_TO_SOME_EXIT,
 	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
 },
-/* Do not reference cpuexit code/data from memexit code/data */
-{
-	.fromsec = { MEM_EXIT_SECTIONS, NULL },
-	.tosec   = { CPU_EXIT_SECTIONS, NULL },
-	.mismatch = XXXEXIT_TO_SOME_EXIT,
-	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
-},
-/* Do not reference memexit code/data from cpuexit code/data */
-{
-	.fromsec = { CPU_EXIT_SECTIONS, NULL },
-	.tosec   = { MEM_EXIT_SECTIONS, NULL },
-	.mismatch = XXXEXIT_TO_SOME_EXIT,
-	.symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL },
-},
 /* Do not use exit code/data from init code */
 {
 	.fromsec = { ALL_INIT_SECTIONS, NULL },
@@ -1089,8 +1058,6 @@ static const struct sectioncheck *section_mismatch(
  * Pattern 2:
  *   Many drivers utilise a *driver container with references to
  *   add, remove, probe functions etc.
- *   These functions may often be marked __cpuinit and we do not want to
- *   warn here.
  *   the pattern is identified by:
  *   tosec   = init or exit section
  *   fromsec = data section
@@ -1249,7 +1216,6 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr,
 /*
  * Convert a section name to the function/data attribute
  * .init.text => __init
- * .cpuinit.data => __cpudata
  * .memexitconst => __memconst
  * etc.
  *