init/modpost: conditionally check section mismatch to __meminit*

This reverts commit eb8f6890 ("Use separate sections for __dev/
_cpu/__mem code/data").

Check section mismatch to __meminit* only when CONFIG_MEMORY_HOTPLUG=n.

With this change, the linker script and modpost become simpler, and we
can get rid of the __ref annotations from the memory hotplug code.

[sfr@canb.auug.org.au: remove MEM_KEEP from arch/powerpc/kernel/vmlinux.lds.S]
  Link: https://lkml.kernel.org/r/20240710093213.2aefb25f@canb.auug.org.au
Link: https://lkml.kernel.org/r/20240706160511.2331061-2-masahiroy@kernel.orgSigned-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/powerpc/kernel/vmlinux.lds.S

@@ -123,8 +123,6 @@ SECTIONS
 		 */
 		*(.sfpr);
 		*(.text.asan.* .text.tsan.*)
-		MEM_KEEP(init.text)
-		MEM_KEEP(exit.text)
 	} :text
 
 	. = ALIGN(PAGE_SIZE);

include/asm-generic/vmlinux.lds.h

@@ -141,14 +141,6 @@
  * often happens at runtime)
  */
 
-#if defined(CONFIG_MEMORY_HOTPLUG)
-#define MEM_KEEP(sec)    *(.mem##sec)
-#define MEM_DISCARD(sec)
-#else
-#define MEM_KEEP(sec)
-#define MEM_DISCARD(sec) *(.mem##sec)
-#endif
-
 #ifndef CONFIG_HAVE_DYNAMIC_FTRACE_NO_PATCHABLE
 #define KEEP_PATCHABLE		KEEP(*(__patchable_function_entries))
 #define PATCHABLE_DISCARDS
@@ -357,7 +349,6 @@
 	*(.data..decrypted)						\
 	*(.ref.data)							\
 	*(.data..shared_aligned) /* percpu related */			\
-	MEM_KEEP(init.data*)						\
 	*(.data.unlikely)						\
 	__start_once = .;						\
 	*(.data.once)							\
@@ -542,7 +533,6 @@
 	/* __*init sections */						\
 	__init_rodata : AT(ADDR(__init_rodata) - LOAD_OFFSET) {		\
 		*(.ref.rodata)						\
-		MEM_KEEP(init.rodata)					\
 	}								\
 									\
 	/* Built-in module parameters. */				\
@@ -593,8 +583,7 @@
 		*(.text.unknown .text.unknown.*)			\
 		NOINSTR_TEXT						\
 		*(.ref.text)						\
-		*(.text.asan.* .text.tsan.*)				\
-	MEM_KEEP(init.text*)						\
+		*(.text.asan.* .text.tsan.*)
 
 
 /* sched.text is aling to function alignment to secure we have same
@@ -701,7 +690,6 @@
 #define INIT_DATA							\
 	KEEP(*(SORT(___kentry+*)))					\
 	*(.init.data .init.data.*)					\
-	MEM_DISCARD(init.data*)						\
 	KERNEL_CTORS()							\
 	MCOUNT_REC()							\
 	*(.init.rodata .init.rodata.*)					\
@@ -709,7 +697,6 @@
 	TRACE_SYSCALLS()						\
 	KPROBE_BLACKLIST()						\
 	ERROR_INJECT_WHITELIST()					\
-	MEM_DISCARD(init.rodata)					\
 	CLK_OF_TABLES()							\
 	RESERVEDMEM_OF_TABLES()						\
 	TIMER_OF_TABLES()						\
@@ -727,8 +714,7 @@
 
 #define INIT_TEXT							\
 	*(.init.text .init.text.*)					\
-	*(.text.startup)						\
-	MEM_DISCARD(init.text*)
+	*(.text.startup)
 
 #define EXIT_DATA							\
 	*(.exit.data .exit.data.*)					\

include/linux/init.h

@@ -84,11 +84,15 @@
 
 #define __exit          __section(".exit.text") __exitused __cold notrace
 
-/* Used for MEMORY_HOTPLUG */
-#define __meminit        __section(".meminit.text") __cold notrace \
-						  __latent_entropy
-#define __meminitdata    __section(".meminit.data")
-#define __meminitconst   __section(".meminit.rodata")
+#ifdef CONFIG_MEMORY_HOTPLUG
+#define __meminit
+#define __meminitdata
+#define __meminitconst
+#else
+#define __meminit	__init
+#define __meminitdata	__initdata
+#define __meminitconst	__initconst
+#endif
 
 /* For assembly routines */
 #define __HEAD		.section	".head.text","ax"

scripts/mod/modpost.c

@@ -776,17 +776,14 @@ static void check_section(const char *modname, struct elf_info *elf,
 
 
 #define ALL_INIT_DATA_SECTIONS \
-	".init.setup", ".init.rodata", ".meminit.rodata", \
-	".init.data", ".meminit.data"
+	".init.setup", ".init.rodata", ".init.data"
 
 #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 ".meminit.*"
-
-#define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS
+#define ALL_INIT_SECTIONS ".init.*"
 #define ALL_EXIT_SECTIONS ".exit.*"
 
 #define DATA_SECTIONS ".data", ".data.rel"
@@ -797,9 +794,7 @@ static void check_section(const char *modname, struct elf_info *elf,
 		".fixup", ".entry.text", ".exception.text", \
 		".coldtext", ".softirqentry.text"
 
-#define INIT_SECTIONS      ".init.*"
-
-#define ALL_TEXT_SECTIONS  ".init.text", ".meminit.text", ".exit.text", \
+#define ALL_TEXT_SECTIONS  ".init.text", ".exit.text", \
 		TEXT_SECTIONS, OTHER_TEXT_SECTIONS
 
 enum mismatch {
@@ -839,12 +834,6 @@ static const struct sectioncheck sectioncheck[] = {
 	.bad_tosec = { ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL },
 	.mismatch = TEXTDATA_TO_ANY_INIT_EXIT,
 },
-/* Do not reference init code/data from meminit code/data */
-{
-	.fromsec = { ALL_XXXINIT_SECTIONS, NULL },
-	.bad_tosec = { INIT_SECTIONS, NULL },
-	.mismatch = XXXINIT_TO_SOME_INIT,
-},
 /* Do not use exit code/data from init code */
 {
 	.fromsec = { ALL_INIT_SECTIONS, NULL },
@@ -859,7 +848,7 @@ static const struct sectioncheck sectioncheck[] = {
 },
 {
 	.fromsec = { ALL_PCI_INIT_SECTIONS, NULL },
-	.bad_tosec = { INIT_SECTIONS, NULL },
+	.bad_tosec = { ALL_INIT_SECTIONS, NULL },
 	.mismatch = ANY_INIT_TO_ANY_EXIT,
 },
 {