linker script: unify usage of discard definition

Discarded sections in different archs share some commonality but have
considerable differences.  This led to linker script for each arch
implementing its own /DISCARD/ definition, which makes maintaining
tedious and adding new entries error-prone.

This patch makes all linker scripts to move discard definitions to the
end of the linker script and use the common DISCARDS macro.  As ld
uses the first matching section definition, archs can include default
discarded sections by including them earlier in the linker script.

ia64 is notable because it first throws away some ia64 specific
subsections and then include the rest of the sections into the final
image, so those sections must be discarded before the inclusion.

defconfig compile tested for x86, x86-64, powerpc, powerpc64, ia64,
alpha, sparc, sparc64 and s390.  Michal Simek tested microblaze.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Tested-by: Michal Simek <monstr@monstr.eu>
Cc: linux-arch@vger.kernel.org
Cc: Michal Simek <monstr@monstr.eu>
Cc: microblaze-uclinux@itee.uq.edu.au
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Tony Luck <tony.luck@intel.com>

25 files changed, 80 insertions, 155 deletions

diff --git a/arch/alpha/kernel/vmlinux.lds.S b/arch/alpha/kernel/vmlinux.lds.S
index 75fe1d6877e..6dc03c35caa 100644
--- a/arch/alpha/kernel/vmlinux.lds.S
+++ b/arch/alpha/kernel/vmlinux.lds.S
@@ -134,14 +134,6 @@ SECTIONS
 	__bss_stop = .;
 	_end = .;
 
-	/* Sections to be discarded */
-	/DISCARD/ : {
-		EXIT_TEXT
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
 	.mdebug 0 : {
 		*(.mdebug)
 	}
@@ -151,4 +143,6 @@ SECTIONS
 
 	STABS_DEBUG
 	DWARF_DEBUG
+
+	DISCARDS
 }
diff --git a/arch/avr32/kernel/vmlinux.lds.S b/arch/avr32/kernel/vmlinux.lds.S
index b8324608ec0..c4b56654349 100644
--- a/arch/avr32/kernel/vmlinux.lds.S
+++ b/arch/avr32/kernel/vmlinux.lds.S
@@ -124,15 +124,11 @@ SECTIONS
 		_end = .;
 	}
 
+	DWARF_DEBUG
+
 	/* When something in the kernel is NOT compiled as a module, the module
 	 * cleanup code and data are put into these segments. Both can then be
 	 * thrown away, as cleanup code is never called unless it's a module.
 	 */
-	/DISCARD/       	: {
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
-	DWARF_DEBUG
+	DISCARDS
 }
diff --git a/arch/blackfin/kernel/vmlinux.lds.S b/arch/blackfin/kernel/vmlinux.lds.S
index 6e8eabd8f0a..d7ffe299b97 100644
--- a/arch/blackfin/kernel/vmlinux.lds.S
+++ b/arch/blackfin/kernel/vmlinux.lds.S
@@ -277,9 +277,5 @@ SECTIONS
 
 	DWARF_DEBUG
 
-	/DISCARD/ :
-	{
-		*(.exitcall.exit)
-		*(.discard)
-	}
+	DISCARDS
 }
diff --git a/arch/cris/kernel/vmlinux.lds.S b/arch/cris/kernel/vmlinux.lds.S
index a3175ebb38c..6c81836b922 100644
--- a/arch/cris/kernel/vmlinux.lds.S
+++ b/arch/cris/kernel/vmlinux.lds.S
@@ -140,13 +140,7 @@ SECTIONS
 	_end = .;
 	__end = .;
 
-	/* Sections to be discarded */
-	/DISCARD/ : {
-		EXIT_TEXT
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-        }
-
 	dram_end = dram_start + (CONFIG_ETRAX_DRAM_SIZE - __CONFIG_ETRAX_VMEM_SIZE)*1024*1024;
+
+	DISCARDS
 }
diff --git a/arch/frv/kernel/vmlinux.lds.S b/arch/frv/kernel/vmlinux.lds.S
index 64b5a5e4d35..7dbf41f68b5 100644
--- a/arch/frv/kernel/vmlinux.lds.S
+++ b/arch/frv/kernel/vmlinux.lds.S
@@ -178,7 +178,7 @@ SECTIONS
 
   .comment 0 : { *(.comment) }
 
-  /DISCARD/ : { *(.discard) }
+  DISCARDS
 }
 
 __kernel_image_size_no_bss = __bss_start - __kernel_image_start;
diff --git a/arch/h8300/kernel/vmlinux.lds.S b/arch/h8300/kernel/vmlinux.lds.S
index 03d6c0df33d..662b02ecb86 100644
--- a/arch/h8300/kernel/vmlinux.lds.S
+++ b/arch/h8300/kernel/vmlinux.lds.S
@@ -152,10 +152,6 @@ SECTIONS
 	__end = . ;
 	__ramstart = .;
 	}
-	/DISCARD/ : {
-		*(.exitcall.exit)
-		*(.discard)
-	}
         .romfs :	
 	{
 		*(.romfs*)
@@ -166,4 +162,6 @@ SECTIONS
 	COMMAND_START = . - 0x200 ;
 	__ramend = . ;
 	}
+
+	DISCARDS
 }
diff --git a/arch/ia64/kernel/vmlinux.lds.S b/arch/ia64/kernel/vmlinux.lds.S
index 13d95897587..eb4214d1c5a 100644
--- a/arch/ia64/kernel/vmlinux.lds.S
+++ b/arch/ia64/kernel/vmlinux.lds.S
@@ -24,15 +24,14 @@ PHDRS {
 }
 SECTIONS
 {
-  /* Sections to be discarded */
+  /* unwind exit sections must be discarded before the rest of the
+     sections get included. */
   /DISCARD/ : {
-	EXIT_TEXT
-	EXIT_DATA
-	*(.exitcall.exit)
-	*(.discard)
 	*(.IA_64.unwind.exit.text)
 	*(.IA_64.unwind_info.exit.text)
-	}
+	*(.comment)
+	*(.note)
+  }
 
   v = PAGE_OFFSET;	/* this symbol is here to make debugging easier... */
   phys_start = _start - LOAD_OFFSET;
@@ -317,7 +316,7 @@ SECTIONS
   .debug_funcnames 0 : { *(.debug_funcnames) }
   .debug_typenames 0 : { *(.debug_typenames) }
   .debug_varnames  0 : { *(.debug_varnames) }
-  /* These must appear regardless of  .  */
-  /DISCARD/ : { *(.comment) }
-  /DISCARD/ : { *(.note) }
+
+  /* Default discards */
+  DISCARDS
 }
diff --git a/arch/m32r/kernel/vmlinux.lds.S b/arch/m32r/kernel/vmlinux.lds.S
index 480a49944cf..de5e21cca6a 100644
--- a/arch/m32r/kernel/vmlinux.lds.S
+++ b/arch/m32r/kernel/vmlinux.lds.S
@@ -120,14 +120,6 @@ SECTIONS
 
   _end = . ;
 
-  /* Sections to be discarded */
-  /DISCARD/ : {
-	EXIT_TEXT
-	EXIT_DATA
-	*(.exitcall.exit)
-	*(.discard)
-	}
-
   /* Stabs debugging sections.  */
   .stab 0 : { *(.stab) }
   .stabstr 0 : { *(.stabstr) }
@@ -136,4 +128,7 @@ SECTIONS
   .stab.index 0 : { *(.stab.index) }
   .stab.indexstr 0 : { *(.stab.indexstr) }
   .comment 0 : { *(.comment) }
+
+  /* Sections to be discarded */
+  DISCARDS
 }
diff --git a/arch/m68k/kernel/vmlinux-std.lds b/arch/m68k/kernel/vmlinux-std.lds
index 905a797ada9..47eac19e8f6 100644
--- a/arch/m68k/kernel/vmlinux-std.lds
+++ b/arch/m68k/kernel/vmlinux-std.lds
@@ -82,14 +82,6 @@ SECTIONS
 
   _end = . ;
 
-  /* Sections to be discarded */
-  /DISCARD/ : {
-	EXIT_TEXT
-	EXIT_DATA
-	*(.exitcall.exit)
-	*(.discard)
-	}
-
   /* Stabs debugging sections.  */
   .stab 0 : { *(.stab) }
   .stabstr 0 : { *(.stabstr) }
@@ -98,4 +90,7 @@ SECTIONS
   .stab.index 0 : { *(.stab.index) }
   .stab.indexstr 0 : { *(.stab.indexstr) }
   .comment 0 : { *(.comment) }
+
+  /* Sections to be discarded */
+  DISCARDS
 }
diff --git a/arch/m68k/kernel/vmlinux-sun3.lds b/arch/m68k/kernel/vmlinux-sun3.lds
index 47d04be322a..03efaf04d7d 100644
--- a/arch/m68k/kernel/vmlinux-sun3.lds
+++ b/arch/m68k/kernel/vmlinux-sun3.lds
@@ -77,14 +77,6 @@ __init_begin = .;
 
   _end = . ;
 
-  /* Sections to be discarded */
-  /DISCARD/ : {
-	EXIT_TEXT
-	EXIT_DATA
-	*(.exitcall.exit)
-	*(.discard)
-	}
-
   .crap : {
 	/* Stabs debugging sections.  */
 	*(.stab)
@@ -97,4 +89,6 @@ __init_begin = .;
 	*(.note)
   }
 
+  /* Sections to be discarded */
+  DISCARDS
 }
diff --git a/arch/m68knommu/kernel/vmlinux.lds.S b/arch/m68knommu/kernel/vmlinux.lds.S
index 68111a61a77..2736a5e309c 100644
--- a/arch/m68knommu/kernel/vmlinux.lds.S
+++ b/arch/m68knommu/kernel/vmlinux.lds.S
@@ -184,13 +184,6 @@ SECTIONS {
 		__init_end = .;
 	} > INIT
 
-	/DISCARD/ : {
-		EXIT_TEXT
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
 	.bss : {
 		. = ALIGN(4);
 		_sbss = . ;
@@ -201,5 +194,6 @@ SECTIONS {
 	 	_end = . ;
 	} > BSS
 
+	DISCARDS
 }
 
diff --git a/arch/microblaze/kernel/vmlinux.lds.S b/arch/microblaze/kernel/vmlinux.lds.S
index 81bebdcb18f..ec5fa91a48d 100644
--- a/arch/microblaze/kernel/vmlinux.lds.S
+++ b/arch/microblaze/kernel/vmlinux.lds.S
@@ -163,5 +163,5 @@ SECTIONS {
 	. = ALIGN(4096);
 	_end = .;
 
-	/DISCARD/ : { *(.discard) }
+	DISCARDS
 }
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index 45901609b74..1474c18fb77 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -176,18 +176,6 @@ SECTIONS
 
 	_end = . ;
 
-	/* Sections to be discarded */
-	/DISCARD/ : {
-		*(.exitcall.exit)
-		*(.discard)
-
-		/* ABI crap starts here */
-		*(.MIPS.options)
-		*(.options)
-		*(.pdr)
-		*(.reginfo)
-	}
-
 	/* These mark the ABI of the kernel for debuggers.  */
 	.mdebug.abi32 : {
 		KEEP(*(.mdebug.abi32))
@@ -213,4 +201,14 @@ SECTIONS
 		*(.gptab.bss)
 		*(.gptab.sbss)
 	}
+
+	/* Sections to be discarded */
+	DISCARDS
+	/DISCARD/ : {
+		/* ABI crap starts here */
+		*(.MIPS.options)
+		*(.options)
+		*(.pdr)
+		*(.reginfo)
+	}
 }
diff --git a/arch/mn10300/kernel/vmlinux.lds.S b/arch/mn10300/kernel/vmlinux.lds.S
index 5609d4962a5..8fcd0f1e21d 100644
--- a/arch/mn10300/kernel/vmlinux.lds.S
+++ b/arch/mn10300/kernel/vmlinux.lds.S
@@ -115,13 +115,10 @@ SECTIONS
   . = ALIGN(PAGE_SIZE);
   pg0 = .;
 
-  /* Sections to be discarded */
-  /DISCARD/ : {
-	EXIT_CALL
-	*(.discard)
-	}
-
   STABS_DEBUG
 
   DWARF_DEBUG
+
+  /* Sections to be discarded */
+  DISCARDS
 }
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index ccf58341845..aea1784edbd 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -237,10 +237,12 @@ SECTIONS
 	/* freed after init ends here */
 	_end = . ;
 
+	STABS_DEBUG
+	.note 0 : { *(.note) }
+
 	/* Sections to be discarded */
+	DISCARDS
 	/DISCARD/ : {
-		*(.exitcall.exit)
-		*(.discard)
 #ifdef CONFIG_64BIT
 		/* temporary hack until binutils is fixed to not emit these
 	 	 * for static binaries
@@ -253,7 +255,4 @@ SECTIONS
 		*(.gnu.hash)
 #endif
 	}
-
-	STABS_DEBUG
-	.note 0 : { *(.note) }	
 }
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index 7fca9355fd3..244e3658983 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -37,13 +37,6 @@ jiffies = jiffies_64 + 4;
 #endif
 SECTIONS
 {
-	/* Sections to be discarded. */
-	/DISCARD/ : {
-	*(.exitcall.exit)
-	*(.discard)
-	EXIT_DATA
-	}
-
 	. = KERNELBASE;
 
 /*
@@ -299,4 +292,7 @@ SECTIONS
 	. = ALIGN(PAGE_SIZE);
 	_end = . ;
 	PROVIDE32 (end = .);
+
+	/* Sections to be discarded. */
+	DISCARDS
 }
diff --git a/arch/s390/kernel/vmlinux.lds.S b/arch/s390/kernel/vmlinux.lds.S
index 98867dfea46..82415c75b99 100644
--- a/arch/s390/kernel/vmlinux.lds.S
+++ b/arch/s390/kernel/vmlinux.lds.S
@@ -157,14 +157,10 @@ SECTIONS
 
 	_end = . ;
 
-	/* Sections to be discarded */
-	/DISCARD/ : {
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
 	/* Debugging sections.	*/
 	STABS_DEBUG
 	DWARF_DEBUG
+
+	/* Sections to be discarded */
+	DISCARDS
 }
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index 766976d27b2..0ce254bca92 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -163,17 +163,14 @@ SECTIONS
 		_end = . ;
 	}
 
+	STABS_DEBUG
+	DWARF_DEBUG
+
 	/*
 	 * When something in the kernel is NOT compiled as a module, the
 	 * module cleanup code and data are put into these segments. Both
 	 * can then be thrown away, as cleanup code is never called unless
 	 * it's a module.
 	 */
-	/DISCARD/ : {
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
-	STABS_DEBUG
-	DWARF_DEBUG
+	DISCARDS
 }
diff --git a/arch/sparc/kernel/vmlinux.lds.S b/arch/sparc/kernel/vmlinux.lds.S
index d63cf914667..866390feb68 100644
--- a/arch/sparc/kernel/vmlinux.lds.S
+++ b/arch/sparc/kernel/vmlinux.lds.S
@@ -171,13 +171,8 @@ SECTIONS
 	}
 	_end = . ;
 
-	/DISCARD/ : {
-		EXIT_TEXT
-		EXIT_DATA
-		*(.exitcall.exit)
-		*(.discard)
-	}
-
 	STABS_DEBUG
 	DWARF_DEBUG
+
+	DISCARDS
 }
diff --git a/arch/um/include/asm/common.lds.S b/arch/um/include/asm/common.lds.S
index cb0248616d4..37ecc5577a9 100644
--- a/arch/um/include/asm/common.lds.S
+++ b/arch/um/include/asm/common.lds.S
@@ -123,8 +123,3 @@
 	__initramfs_end = .;
   }
 
-  /* Sections to be discarded */
-  /DISCARD/ : {
- 	*(.exitcall.exit)
-  }
-
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index 2916d6eadff..715a188c047 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -157,5 +157,5 @@ SECTIONS
 
   DWARF_DEBUG
 
-  /DISCARD/	: { *(.discard) }
+  DISCARDS
 }
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index 1f8a622cabe..2ebd39765db 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -101,5 +101,5 @@ SECTIONS
 
   DWARF_DEBUG
 
-  /DISCARD/	: { *(.discard) }
+  DISCARDS
 }
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 367e8788204..b600c843710 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -387,15 +387,12 @@ SECTIONS
 		_end = .;
 	}
 
-	/* Sections to be discarded */
-	/DISCARD/ : {
-		*(.exitcall.exit)
-		*(.eh_frame)
-		*(.discard)
-	}
-
         STABS_DEBUG
         DWARF_DEBUG
+
+	/* Sections to be discarded */
+	DISCARDS
+	/DISCARD/ : { *(.eh_frame) }
 }
 
 
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index b1e24638acd..921b6ff3b64 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -280,16 +280,6 @@ SECTIONS
     *(.ResetVector.text)
   }
 
-  /* Sections to be discarded */
-  /DISCARD/ :
-  {
-	*(.exit.literal)
-	EXIT_TEXT
-	EXIT_DATA
-        *(.exitcall.exit)
-	*(.discard)
-  }
-
   .xt.lit : { *(.xt.lit) }
   .xt.prop : { *(.xt.prop) }
 
@@ -322,4 +312,8 @@ SECTIONS
     *(.xt.lit)
     *(.gnu.linkonce.p*)
   }
+
+  /* Sections to be discarded */
+  DISCARDS
+  /DISCARD/ : { *(.exit.literal) }
 }
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index c5c18ac878a..ab8ea9b7741 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -35,13 +35,10 @@
  *	__bss_stop = .;
  *	_end = .;
  *
- *	/DISCARD/ : {
- *		EXIT_TEXT
- *		EXIT_DATA
- *		EXIT_CALL
- *	}
  *	STABS_DEBUG
  *	DWARF_DEBUG
+ *
+ *	DISCARDS		// must be the last
  * }
  *
  * [__init_begin, __init_end] is the init section that may be freed after init
@@ -629,11 +626,20 @@
 #define INIT_RAM_FS
 #endif
 
+/*
+ * Default discarded sections.
+ *
+ * Some archs want to discard exit text/data at runtime rather than
+ * link time due to cross-section references such as alt instructions,
+ * bug table, eh_frame, etc.  DISCARDS must be the last of output
+ * section definitions so that such archs put those in earlier section
+ * definitions.
+ */
 #define DISCARDS							\
 	/DISCARD/ : {							\
 	EXIT_TEXT							\
 	EXIT_DATA							\
-	*(.exitcall.exit)						\
+	EXIT_CALL							\
 	*(.discard)							\
 	}