[PATCH] powerpc: link error on orphan sections

From: Nicholas Piggin <npiggin@gmail.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Nicholas Piggin <npiggin@gmail.com>
Subject: [PATCH] powerpc: link error on orphan sections
Date: Wed, 12 Oct 2016 18:00:20 +1100	[thread overview]
Message-ID: <20161012070020.30170-1-npiggin@gmail.com> (raw)

Add --orphan-handling=error to final link flags. This ensures we have to
handle all sections. This would have caught subtle breakage such as
7de3b27bac47da9de08409df1d69664acbb72197 at build-time.

Also bring some wayward sections into the fold:
- .text.hot and .text.unlikely are compiler generated sections.
- .sfpr is a linker generated section for register save functions.
- .sdata2, .dynsbss, .plt are used by PPC32
- We previously did not specify DWARF_DEBUG or STABS_DEBUG
- DWARF_DEBUG did not include DWARF3 .debug_ranges
- A number of sections are unused.

I don't know if I've exactly got everything right here, particularly
with ppc32, so would appreciate people casting their eye over it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/Makefile             |  2 +-
 arch/powerpc/kernel/vmlinux.lds.S | 16 ++++++++++++++--
 include/asm-generic/vmlinux.lds.h |  3 +++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 50d020a..a3f2784 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -90,7 +90,7 @@ endif
 
 LDFLAGS_vmlinux-y := -Bstatic
 LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
-LDFLAGS_vmlinux	:= $(LDFLAGS_vmlinux-y)
+LDFLAGS_vmlinux	:= $(LDFLAGS_vmlinux-y) --orphan-handling=error
 
 ifeq ($(CONFIG_PPC64),y)
 ifeq ($(call cc-option-yn,-mcmodel=medium),y)
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 8295f51..9f4d85e 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -97,7 +97,7 @@ SECTIONS
 	.text : AT(ADDR(.text) - LOAD_OFFSET) {
 		ALIGN_FUNCTION();
 		/* careful! __ftr_alt_* sections need to be close to .text */
-		*(.text .fixup __ftr_alt_* .ref.text)
+		*(.text.hot .text .text.fixup .text.unlikely .fixup __ftr_alt_* .ref.text .sfpr) \
 		SCHED_TEXT
 		CPUIDLE_TEXT
 		LOCK_TEXT
@@ -256,7 +256,9 @@ SECTIONS
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {
 		DATA_DATA
 		*(.sdata)
+		*(.sdata2)
 		*(.got.plt) *(.got)
+		*(.plt)
 	}
 #else
 	.data : AT(ADDR(.data) - LOAD_OFFSET) {
@@ -317,6 +319,16 @@ SECTIONS
 	_end = . ;
 	PROVIDE32 (end = .);
 
-	/* Sections to be discarded. */
+	STABS_DEBUG
+
+	DWARF_DEBUG
+
 	DISCARDS
+	/DISCARD/ : {
+		*(*.EMB.apuinfo)
+		*(.glink .iplt .plt .rela* .comment)
+		*(.gnu.version*)
+		*(.gnu.attributes)
+		*(.eh_frame)
+	}
 }
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 3e42bcd..264ebb3 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -581,6 +581,7 @@
 #define SBSS(sbss_align)						\
 	. = ALIGN(sbss_align);						\
 	.sbss : AT(ADDR(.sbss) - LOAD_OFFSET) {				\
+		*(.dynsbss)						\
 		*(.sbss)						\
 		*(.scommon)						\
 	}
@@ -627,6 +628,8 @@
 		.debug_str      0 : { *(.debug_str) }			\
 		.debug_loc      0 : { *(.debug_loc) }			\
 		.debug_macinfo  0 : { *(.debug_macinfo) }		\
+		/* DWARF 3 */						\
+		.debug_ranges	0 : { *(.debug_ranges) }		\
 		/* SGI/MIPS DWARF 2 extensions */			\
 		.debug_weaknames 0 : { *(.debug_weaknames) }		\
 		.debug_funcnames 0 : { *(.debug_funcnames) }		\
-- 
2.9.3
