x86: linker script and assembly tidying

Build with -fno-asynchronous-unwind-tables so that a .debug_frame
section is properly created, discard .eh_frame, and don't generate
xxx_end symbols when using ASM_END. Also, remove the unused ASM_IRET
macro.

4 files changed, 24 insertions, 18 deletions

diff --git a/arch/x86/Makefrag.am b/arch/x86/Makefrag.am
index a6baf70d..71aabbc9 100644
--- a/arch/x86/Makefrag.am
+++ b/arch/x86/Makefrag.am
@@ -37,6 +37,10 @@ EXTRA_DIST += arch/x86/x15.lds.S $(x86_FILES)
 
 if X86
 
+# Store unwind information in .debug_frame instead of .eh_frame. Unwind
+# tables aren't used at runtime, so using a debug section reduces the kernel
+# code size.
+AM_CFLAGS += -fno-asynchronous-unwind-tables
 x15_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
 
 if I386
diff --git a/arch/x86/machine/asm.h b/arch/x86/machine/asm.h
index c2c4e997..6118bb8a 100644
--- a/arch/x86/machine/asm.h
+++ b/arch/x86/machine/asm.h
@@ -18,9 +18,11 @@
 #ifndef _X86_ASM_H
 #define _X86_ASM_H
 
-#include <machine/param.h>
+#ifndef __ASSEMBLER__
+#warning "asm.h included from a C file"
+#endif /* __ASSEMBLER__ */
 
-#ifdef __ASSEMBLER__
+#include <machine/param.h>
 
 #define ASM_ENTRY(x)    \
 .align TEXT_ALIGN;      \
@@ -35,15 +37,6 @@ x:
 x:
 
 #define ASM_END(x)  \
-.size x, . - x;     \
-x ## _end:
-
-#ifdef __LP64__
-#define ASM_IRET iretq
-#else /* __LP64__ */
-#define ASM_IRET iret
-#endif /* __LP64__ */
-
-#endif /* __ASSEMBLER__ */
+.size x, . - x
 
 #endif /* _X86_ASM_H */
diff --git a/arch/x86/machine/boot_asm.S b/arch/x86/machine/boot_asm.S
index 49074f94..d29689e2 100644
--- a/arch/x86/machine/boot_asm.S
+++ b/arch/x86/machine/boot_asm.S
@@ -290,6 +290,7 @@ ASM_DATA(boot_gdt)
  .quad 0x00209a0000000000   /* 64-bit code segment selector */
 #endif /* __LP64__ */
 ASM_END(boot_gdt)
+boot_gdt_end:
 
 ASM_DATA(boot_mp_trampoline_size)
  .long . - boot_mp_trampoline
diff --git a/arch/x86/x15.lds.S b/arch/x86/x15.lds.S
index 4959c067..8d144d12 100644
--- a/arch/x86/x15.lds.S
+++ b/arch/x86/x15.lds.S
@@ -25,7 +25,7 @@ SECTIONS
     . = BOOT_OFFSET;
     _init = .;
 
-    .init ALIGN(PAGE_SIZE): {
+    .init ALIGN(PAGE_SIZE) : {
         *(.init.hdr)
         *(.init.text)
         *(.init.data)
@@ -37,33 +37,41 @@ SECTIONS
     . += KERNEL_OFFSET;
     _text = .;
 
-    .text ALIGN(PAGE_SIZE): AT(BOOT_VTOP(ADDR(.text))) {
+    .text ALIGN(PAGE_SIZE) : AT(BOOT_VTOP(ADDR(.text))) {
         *(.text)
     } : text
 
     . = ALIGN(PAGE_SIZE);
     _rodata = .;
 
-    .rodata ALIGN(PAGE_SIZE): AT(BOOT_VTOP(ADDR(.rodata))) {
+    .rodata ALIGN(PAGE_SIZE) : AT(BOOT_VTOP(ADDR(.rodata))) {
         *(.rodata)
     } : rodata
 
-    .notes ALIGN(8): AT(BOOT_VTOP(ADDR(.notes))) {
+    .notes ALIGN(8) : AT(BOOT_VTOP(ADDR(.notes))) {
         *(.note.*)
     } : rodata
 
     . = ALIGN(PAGE_SIZE);
     _data = .;
 
-    .data ALIGN(PAGE_SIZE): AT(BOOT_VTOP(ADDR(.data))) {
+    .data ALIGN(PAGE_SIZE) : AT(BOOT_VTOP(ADDR(.data))) {
         *(.data)
     } : data
 
-    .bss ALIGN(8): AT(BOOT_VTOP(ADDR(.bss))) {
+    .bss ALIGN(8) : AT(BOOT_VTOP(ADDR(.bss))) {
         *(.bss)
         *(COMMON)
     } : data
 
     . = ALIGN(PAGE_SIZE);
     _end = .;
+
+    /*
+     * A global offset section is created because of linking with libgcc.
+     * Is it safe to discard it ?
+     */
+    /DISCARD/ : {
+        *(.eh_frame)
+    }
 }