[PATCH 0/7] kbuild patches for 4.10

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* [PATCH 0/7] kbuild patches for 4.10
@ 2016-11-23 16:41 Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 1/7] kbuild: kallsyms allow 3-pass generation if symbols size has changed Nicholas Piggin
                   ` (7 more replies)
  0 siblings, 8 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

Hi,

I have a few various kbuild patches for review and  consideration
for 4.10 branch that did not make 4.9. All of these except the first
one have been posted before without big changes. The first, I posted
an RFC for moving kallsyms data section but this approach is simpler.

All patches are independent, so any can be taken in any order. I'm
posting as a group just for convenience but if that is wrong then I
will submit individual patches in future.

Thanks,
Nick

Nicholas Piggin (7):
  kbuild: kallsyms allow 3-pass generation if symbols size has changed
  kbuild: thin archives for multi-y targets
  kbuild/genksyms: handle va_list type
  kbuild: improve linker compatibility with lib-ksyms.o build
  kbuild: keep data tables through dead code elimination
  kbuild: modpost warn if export version crc is missing
  kbuild: minor improvement for thin archives build

 include/asm-generic/vmlinux.lds.h | 68 +++++++++++++++++++--------------------
 scripts/Makefile.build            | 15 ++++++---
 scripts/genksyms/keywords.gperf   |  1 +
 scripts/genksyms/parse.y          |  2 ++
 scripts/link-vmlinux.sh           | 37 ++++++++++++---------
 scripts/mod/modpost.c             |  6 ++++
 6 files changed, 76 insertions(+), 53 deletions(-)

-- 
2.10.2


^ permalink raw reply	[flat|nested] 9+ messages in thread

* [PATCH 1/7] kbuild: kallsyms allow 3-pass generation if symbols size has changed
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 2/7] kbuild: thin archives for multi-y targets Nicholas Piggin
                   ` (6 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

kallsyms generation is not foolproof, due to some linkers adding
symbols (e.g., branch trampolines) when a binary size changes.
Have it attempt a 3rd pass automatically if the kallsyms size changes
in the 2nd pass.

This allows powerpc64 allyesconfig to build without adding another
pass when it's not required.

This can be solved other ways by directing the linker not to add labels
on branch stubs, or to move kallsyms near the end of the image. The
former is undesirable for debugging/tracing, and the latter is a more
significant change that requires more testing and review.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/link-vmlinux.sh | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index f742c65..6b94fe4 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -246,10 +246,14 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
 	#     the right size, but due to the added section, some
 	#     addresses have shifted.
 	#     From here, we generate a correct .tmp_kallsyms2.o
-	# 2a) We may use an extra pass as this has been necessary to
-	#     woraround some alignment related bugs.
-	#     KALLSYMS_EXTRA_PASS=1 is used to trigger this.
-	# 3)  The correct ${kallsymso} is linked into the final vmlinux.
+	# 3)  That link may have expanded the kernel image enough that
+	#     more linker branch stubs / trampolines had to be added, which
+	#     introduces new names, which further expands kallsyms. Do another
+	#     pass if that is the case. In theory it's possible this results
+	#     in even more stubs, but unlikely.
+	#     KALLSYMS_EXTRA_PASS=1 may also used to debug or work around
+	#     other bugs.
+	# 4)  The correct ${kallsymso} is linked into the final vmlinux.
 	#
 	# a)  Verify that the System.map from vmlinux matches the map from
 	#     ${kallsymso}.
@@ -265,8 +269,11 @@ if [ -n "${CONFIG_KALLSYMS}" ]; then
 	vmlinux_link .tmp_kallsyms1.o .tmp_vmlinux2
 	kallsyms .tmp_vmlinux2 .tmp_kallsyms2.o
 
-	# step 2a
-	if [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
+	# step 3
+	size1=$(stat -c "%s" .tmp_kallsyms1.o)
+	size2=$(stat -c "%s" .tmp_kallsyms2.o)
+
+	if [ $size1 -ne $size2 ] || [ -n "${KALLSYMS_EXTRA_PASS}" ]; then
 		kallsymso=.tmp_kallsyms3.o
 		kallsyms_vmlinux=.tmp_vmlinux3
 
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 2/7] kbuild: thin archives for multi-y targets
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 1/7] kbuild: kallsyms allow 3-pass generation if symbols size has changed Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 3/7] kbuild/genksyms: handle va_list type Nicholas Piggin
                   ` (5 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

THIN_ARCHIVES builds archives for built-in.o targets, have it build
multi-y targets as archives as well.

This saves another ~15% of the size of intermediate artifacts in the
build tree. After this patch, the linker is only used in final link,
and special cases like vdsos.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/Makefile.build | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 7675d11..41d2901 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -517,11 +517,18 @@ $($(subst $(obj)/,,$(@:.o=-objs)))    \
 $($(subst $(obj)/,,$(@:.o=-y)))       \
 $($(subst $(obj)/,,$(@:.o=-m)))), $^)
 
-quiet_cmd_link_multi-y = LD      $@
-cmd_link_multi-y = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
+cmd_link_multi-link = $(LD) $(ld_flags) -r -o $@ $(link_multi_deps) $(cmd_secanalysis)
+
+ifdef CONFIG_THIN_ARCHIVES
+  quiet_cmd_link_multi-y = AR      $@
+  cmd_link_multi-y = rm -f $@; $(AR) rcST$(KBUILD_ARFLAGS) $@ $(link_multi_deps)
+else
+  quiet_cmd_link_multi-y = LD      $@
+  cmd_link_multi-y = $(cmd_link_multi-link)
+endif
 
 quiet_cmd_link_multi-m = LD [M]  $@
-cmd_link_multi-m = $(cmd_link_multi-y)
+cmd_link_multi-m = $(cmd_link_multi-link)
 
 $(multi-used-y): FORCE
 	$(call if_changed,link_multi-y)
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 3/7] kbuild/genksyms: handle va_list type
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 1/7] kbuild: kallsyms allow 3-pass generation if symbols size has changed Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 2/7] kbuild: thin archives for multi-y targets Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 4/7] kbuild: improve linker compatibility with lib-ksyms.o build Nicholas Piggin
                   ` (4 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

genksyms currently does not handle va_list. Add the __builtin_va_list
keyword as a type. This reduces the amount of syntax errors thrown,
but so far no export symbol has a type with a va_list argument, so
there is currently no bug in the end result.

Note: this patch does not regenerate shipped parser files.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/genksyms/keywords.gperf | 1 +
 scripts/genksyms/parse.y        | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/scripts/genksyms/keywords.gperf b/scripts/genksyms/keywords.gperf
index a9096d9..bd4c4b2 100644
--- a/scripts/genksyms/keywords.gperf
+++ b/scripts/genksyms/keywords.gperf
@@ -27,6 +27,7 @@ __typeof, TYPEOF_KEYW
 __typeof__, TYPEOF_KEYW
 __volatile, VOLATILE_KEYW
 __volatile__, VOLATILE_KEYW
+__builtin_va_list, VA_LIST_KEYW
 # According to rth, c99 defines _Bool, __restrict, __restrict__, restrict.  KAO
 _Bool, BOOL_KEYW
 _restrict, RESTRICT_KEYW
diff --git a/scripts/genksyms/parse.y b/scripts/genksyms/parse.y
index 723ab30..4fba255 100644
--- a/scripts/genksyms/parse.y
+++ b/scripts/genksyms/parse.y
@@ -98,6 +98,7 @@ static void record_compound(struct string_list **keyw,
 %token VOID_KEYW
 %token VOLATILE_KEYW
 %token TYPEOF_KEYW
+%token VA_LIST_KEYW
 
 %token EXPORT_SYMBOL_KEYW
 
@@ -261,6 +262,7 @@ simple_type_specifier:
 	| DOUBLE_KEYW
 	| VOID_KEYW
 	| BOOL_KEYW
+	| VA_LIST_KEYW
 	| TYPE			{ (*$1)->tag = SYM_TYPEDEF; $$ = $1; }
 	;
 
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 4/7] kbuild: improve linker compatibility with lib-ksyms.o build
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
                   ` (2 preceding siblings ...)
  2016-11-23 16:41 ` [PATCH 3/7] kbuild/genksyms: handle va_list type Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 5/7] kbuild: keep data tables through dead code elimination Nicholas Piggin
                   ` (3 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

lib-ksyms.o is created by linking an empty input file with a linker
script containing the interesting bits. Currently the empty input file
is an archive containing nothing, however this causes the gold linker
to segfault.

I have opened a bug against gold

  https://sourceware.org/bugzilla/show_bug.cgi?id=20767

However this can be worked around by assembling an empty file to link
with instead. The resulting lib-ksyms.o is slightly larger (seemingly
due to empty .text, .data, .bss setions added), but final linked
output should not be changed.

Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/Makefile.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 41d2901..8925209 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -490,7 +490,7 @@ quiet_cmd_export_list = EXPORTS $@
 cmd_export_list = $(OBJDUMP) -h $< | \
 	sed -ne '/___ksymtab/{s/.*+/$(ref_prefix)/;s/ .*/)/;p}' >$(ksyms-lds);\
 	rm -f $(dummy-object);\
-	$(AR) rcs$(KBUILD_ARFLAGS) $(dummy-object);\
+	echo | $(CC) $(a_flags) -c -o $(dummy-object) -x assembler -;\
 	$(LD) $(ld_flags) -r -o $@ -T $(ksyms-lds) $(dummy-object);\
 	rm $(dummy-object) $(ksyms-lds)
 
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 5/7] kbuild: keep data tables through dead code elimination
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
                   ` (3 preceding siblings ...)
  2016-11-23 16:41 ` [PATCH 4/7] kbuild: improve linker compatibility with lib-ksyms.o build Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 6/7] kbuild: modpost warn if export version crc is missing Nicholas Piggin
                   ` (2 subsequent siblings)
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild, Paul Burton

When CONFIG_LD_DEAD_CODE_DATA_ELIMINATION is enabled we must ensure
that we still keep various programatically-accessed tables.

[npiggin: Fold Paul's patches into one, and add a few more tables.
 diff symbol tables of allyesconfig with/without -gc-sections shows up
 lost tables quite easily.]

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 include/asm-generic/vmlinux.lds.h | 68 +++++++++++++++++++--------------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 31e1d63..9faa26c 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -114,7 +114,7 @@
 #ifdef CONFIG_KPROBES
 #define KPROBE_BLACKLIST()	. = ALIGN(8);				      \
 				VMLINUX_SYMBOL(__start_kprobe_blacklist) = .; \
-				*(_kprobe_blacklist)			      \
+				KEEP(*(_kprobe_blacklist))		      \
 				VMLINUX_SYMBOL(__stop_kprobe_blacklist) = .;
 #else
 #define KPROBE_BLACKLIST()
@@ -123,10 +123,10 @@
 #ifdef CONFIG_EVENT_TRACING
 #define FTRACE_EVENTS()	. = ALIGN(8);					\
 			VMLINUX_SYMBOL(__start_ftrace_events) = .;	\
-			*(_ftrace_events)				\
+			KEEP(*(_ftrace_events))				\
 			VMLINUX_SYMBOL(__stop_ftrace_events) = .;	\
 			VMLINUX_SYMBOL(__start_ftrace_enum_maps) = .;	\
-			*(_ftrace_enum_map)				\
+			KEEP(*(_ftrace_enum_map))			\
 			VMLINUX_SYMBOL(__stop_ftrace_enum_maps) = .;
 #else
 #define FTRACE_EVENTS()
@@ -134,10 +134,10 @@
 
 #ifdef CONFIG_TRACING
 #define TRACE_PRINTKS() VMLINUX_SYMBOL(__start___trace_bprintk_fmt) = .;      \
-			 *(__trace_printk_fmt) /* Trace_printk fmt' pointer */ \
+			 KEEP(*(__trace_printk_fmt)) /* Trace_printk fmt' pointer */ \
 			 VMLINUX_SYMBOL(__stop___trace_bprintk_fmt) = .;
 #define TRACEPOINT_STR() VMLINUX_SYMBOL(__start___tracepoint_str) = .;	\
-			 *(__tracepoint_str) /* Trace_printk fmt' pointer */ \
+			 KEEP(*(__tracepoint_str)) /* Trace_printk fmt' pointer */ \
 			 VMLINUX_SYMBOL(__stop___tracepoint_str) = .;
 #else
 #define TRACE_PRINTKS()
@@ -147,7 +147,7 @@
 #ifdef CONFIG_FTRACE_SYSCALLS
 #define TRACE_SYSCALLS() . = ALIGN(8);					\
 			 VMLINUX_SYMBOL(__start_syscalls_metadata) = .;	\
-			 *(__syscalls_metadata)				\
+			 KEEP(*(__syscalls_metadata))			\
 			 VMLINUX_SYMBOL(__stop_syscalls_metadata) = .;
 #else
 #define TRACE_SYSCALLS()
@@ -156,7 +156,7 @@
 #ifdef CONFIG_SERIAL_EARLYCON
 #define EARLYCON_TABLE() STRUCT_ALIGN();			\
 			 VMLINUX_SYMBOL(__earlycon_table) = .;	\
-			 *(__earlycon_table)			\
+			 KEEP(*(__earlycon_table))		\
 			 VMLINUX_SYMBOL(__earlycon_table_end) = .;
 #else
 #define EARLYCON_TABLE()
@@ -169,8 +169,8 @@
 #define _OF_TABLE_1(name)						\
 	. = ALIGN(8);							\
 	VMLINUX_SYMBOL(__##name##_of_table) = .;			\
-	*(__##name##_of_table)						\
-	*(__##name##_of_table_end)
+	KEEP(*(__##name##_of_table))					\
+	KEEP(*(__##name##_of_table_end))
 
 #define CLKSRC_OF_TABLES()	OF_TABLE(CONFIG_CLKSRC_OF, clksrc)
 #define IRQCHIP_OF_MATCH_TABLE() OF_TABLE(CONFIG_IRQCHIP, irqchip)
@@ -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()						\
@@ -274,10 +274,10 @@
 		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 */	\
 	}								\
@@ -291,35 +291,35 @@
 	/* PCI quirks */						\
 	.pci_fixup        : AT(ADDR(.pci_fixup) - LOAD_OFFSET) {	\
 		VMLINUX_SYMBOL(__start_pci_fixups_early) = .;		\
-		*(.pci_fixup_early)					\
+		KEEP(*(.pci_fixup_early))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_early) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_header) = .;		\
-		*(.pci_fixup_header)					\
+		KEEP(*(.pci_fixup_header))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_header) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_final) = .;		\
-		*(.pci_fixup_final)					\
+		KEEP(*(.pci_fixup_final))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_final) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_enable) = .;		\
-		*(.pci_fixup_enable)					\
+		KEEP(*(.pci_fixup_enable))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_enable) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_resume) = .;		\
-		*(.pci_fixup_resume)					\
+		KEEP(*(.pci_fixup_resume))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_resume) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_resume_early) = .;	\
-		*(.pci_fixup_resume_early)				\
+		KEEP(*(.pci_fixup_resume_early))			\
 		VMLINUX_SYMBOL(__end_pci_fixups_resume_early) = .;	\
 		VMLINUX_SYMBOL(__start_pci_fixups_suspend) = .;		\
-		*(.pci_fixup_suspend)					\
+		KEEP(*(.pci_fixup_suspend))				\
 		VMLINUX_SYMBOL(__end_pci_fixups_suspend) = .;		\
 		VMLINUX_SYMBOL(__start_pci_fixups_suspend_late) = .;	\
-		*(.pci_fixup_suspend_late)				\
+		KEEP(*(.pci_fixup_suspend_late))			\
 		VMLINUX_SYMBOL(__end_pci_fixups_suspend_late) = .;	\
 	}								\
 									\
 	/* 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) = .;			\
 	}								\
 									\
@@ -397,7 +397,7 @@
 									\
 	/* Kernel symbol table: strings */				\
         __ksymtab_strings : AT(ADDR(__ksymtab_strings) - LOAD_OFFSET) {	\
-		KEEP(*(__ksymtab_strings))				\
+		*(__ksymtab_strings)					\
 	}								\
 									\
 	/* __*init sections */						\
@@ -410,14 +410,14 @@
 	/* 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) = .;			\
@@ -520,7 +520,7 @@
 	. = 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) = .;			\
 	}
 
@@ -536,9 +536,9 @@
 #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()
@@ -662,7 +662,7 @@
 	. = 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
@@ -674,7 +674,7 @@
 	. = ALIGN(4);							\
 	.tracedata : AT(ADDR(.tracedata) - LOAD_OFFSET) {		\
 		VMLINUX_SYMBOL(__tracedata_start) = .;			\
-		*(.tracedata)						\
+		KEEP(*(.tracedata))					\
 		VMLINUX_SYMBOL(__tracedata_end) = .;			\
 	}
 #else
@@ -691,7 +691,7 @@
 #define INIT_SETUP(initsetup_align)					\
 		. = ALIGN(initsetup_align);				\
 		VMLINUX_SYMBOL(__setup_start) = .;			\
-		*(.init.setup)						\
+		KEEP(*(.init.setup))					\
 		VMLINUX_SYMBOL(__setup_end) = .;
 
 #define INIT_CALLS_LEVEL(level)						\
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 6/7] kbuild: modpost warn if export version crc is missing
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
                   ` (4 preceding siblings ...)
  2016-11-23 16:41 ` [PATCH 5/7] kbuild: keep data tables through dead code elimination Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-23 16:41 ` [PATCH 7/7] kbuild: minor improvement for thin archives build Nicholas Piggin
  2016-11-29 21:25 ` [PATCH 0/7] kbuild patches for 4.10 Michal Marek
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

This catches the failing ceph CRC on with:

    LD      vmlinux.o
    MODPOST vmlinux.o
  WARNING: EXPORT symbol "ceph_monc_do_statfs" [vmlinux] version
  generation failed, symbol will not be versioned.

When the modules referring to exported symbols are built, there is an
existing warning for missing CRC, but it's not always the case such
any such module will be built, and in any case it is useful to get a
warning at the source.

This gets a little verbose with CONFIG_DEBUG_SECTION_MISMATCH,
producing a warning with each object linked, but I didn't think
that warranted extra complexity to avoid.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/mod/modpost.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index bd83497..08f62a1 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -609,6 +609,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 {
 	unsigned int crc;
 	enum export export;
+	bool is_crc = false;
 
 	if ((!is_vmlinux(mod->name) || mod->is_dot_o) &&
 	    strncmp(symname, "__ksymtab", 9) == 0)
@@ -618,6 +619,7 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 
 	/* CRC'd symbol */
 	if (strncmp(symname, CRC_PFX, strlen(CRC_PFX)) == 0) {
+		is_crc = true;
 		crc = (unsigned int) sym->st_value;
 		sym_update_crc(symname + strlen(CRC_PFX), mod, crc,
 				export);
@@ -663,6 +665,10 @@ static void handle_modversions(struct module *mod, struct elf_info *info,
 		else
 			symname++;
 #endif
+		if (is_crc) {
+			const char *e = is_vmlinux(mod->name) ?"":".ko";
+			warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n", symname + strlen(CRC_PFX), mod->name, e);
+		}
 		mod->unres = alloc_symbol(symname,
 					  ELF_ST_BIND(sym->st_info) == STB_WEAK,
 					  mod->unres);
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* [PATCH 7/7] kbuild: minor improvement for thin archives build
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
                   ` (5 preceding siblings ...)
  2016-11-23 16:41 ` [PATCH 6/7] kbuild: modpost warn if export version crc is missing Nicholas Piggin
@ 2016-11-23 16:41 ` Nicholas Piggin
  2016-11-29 21:25 ` [PATCH 0/7] kbuild patches for 4.10 Michal Marek
  7 siblings, 0 replies; 9+ messages in thread
From: Nicholas Piggin @ 2016-11-23 16:41 UTC (permalink / raw)
  To: Michal Marek; +Cc: Nicholas Piggin, linux-kbuild

The root built-in.o archive is currently generated before all object
files are built for the final link, due to final build of init/ after
version update. In practice it seems like it doesn't matter because
the archive symbol table does not change, but it is more logical to
create the final archive as the last step.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 scripts/link-vmlinux.sh | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index 6b94fe4..c802913 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -209,15 +209,6 @@ case "${KCONFIG_CONFIG}" in
 	. "./${KCONFIG_CONFIG}"
 esac
 
-archive_builtin
-
-#link vmlinux.o
-info LD vmlinux.o
-modpost_link vmlinux.o
-
-# modpost vmlinux.o to check for section mismatches
-${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
-
 # Update version
 info GEN .version
 if [ ! -r .version ]; then
@@ -231,6 +222,15 @@ fi;
 # final build of init/
 ${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}"
 
+archive_builtin
+
+#link vmlinux.o
+info LD vmlinux.o
+modpost_link vmlinux.o
+
+# modpost vmlinux.o to check for section mismatches
+${MAKE} -f "${srctree}/scripts/Makefile.modpost" vmlinux.o
+
 kallsymso=""
 kallsyms_vmlinux=""
 if [ -n "${CONFIG_KALLSYMS}" ]; then
-- 
2.10.2


^ permalink raw reply related	[flat|nested] 9+ messages in thread

* Re: [PATCH 0/7] kbuild patches for 4.10
  2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
                   ` (6 preceding siblings ...)
  2016-11-23 16:41 ` [PATCH 7/7] kbuild: minor improvement for thin archives build Nicholas Piggin
@ 2016-11-29 21:25 ` Michal Marek
  7 siblings, 0 replies; 9+ messages in thread
From: Michal Marek @ 2016-11-29 21:25 UTC (permalink / raw)
  To: Nicholas Piggin; +Cc: linux-kbuild

Dne 23.11.2016 v 17:41 Nicholas Piggin napsal(a):
> Hi,
> 
> I have a few various kbuild patches for review and  consideration
> for 4.10 branch that did not make 4.9. All of these except the first
> one have been posted before without big changes. The first, I posted
> an RFC for moving kallsyms data section but this approach is simpler.
> 
> All patches are independent, so any can be taken in any order. I'm
> posting as a group just for convenience but if that is wrong then I
> will submit individual patches in future.

Thanks, I applied them to kbuild.git#kbuild now.

Michal

^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2016-11-29 21:25 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2016-11-23 16:41 [PATCH 0/7] kbuild patches for 4.10 Nicholas Piggin
2016-11-23 16:41 ` [PATCH 1/7] kbuild: kallsyms allow 3-pass generation if symbols size has changed Nicholas Piggin
2016-11-23 16:41 ` [PATCH 2/7] kbuild: thin archives for multi-y targets Nicholas Piggin
2016-11-23 16:41 ` [PATCH 3/7] kbuild/genksyms: handle va_list type Nicholas Piggin
2016-11-23 16:41 ` [PATCH 4/7] kbuild: improve linker compatibility with lib-ksyms.o build Nicholas Piggin
2016-11-23 16:41 ` [PATCH 5/7] kbuild: keep data tables through dead code elimination Nicholas Piggin
2016-11-23 16:41 ` [PATCH 6/7] kbuild: modpost warn if export version crc is missing Nicholas Piggin
2016-11-23 16:41 ` [PATCH 7/7] kbuild: minor improvement for thin archives build Nicholas Piggin
2016-11-29 21:25 ` [PATCH 0/7] kbuild patches for 4.10 Michal Marek

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