[PATCH v8 11/28] x86/asm/head: annotate data appropriatelly
From: Jiri Slaby
Date: Thu Aug 08 2019 - 06:39:57 EST
Use the new SYM_DATA, SYM_DATA_START, and SYM_DATA_END in both 32 and 64
bit heads. In the 64-bit version, define also
SYM_DATA_START_PAGE_ALIGNED locally using the new SYM_START. It is used
in the code instead of NEXT_PAGE() which was defined in this file and
has been using the obsolete macro GLOBAL().
Now, the data in the 64-bit object file look sane:
Value Size Type Bind Vis Ndx Name
0000 4096 OBJECT GLOBAL DEFAULT 15 init_level4_pgt
1000 4096 OBJECT GLOBAL DEFAULT 15 level3_kernel_pgt
2000 2048 OBJECT GLOBAL DEFAULT 15 level2_kernel_pgt
3000 4096 OBJECT GLOBAL DEFAULT 15 level2_fixmap_pgt
4000 4096 OBJECT GLOBAL DEFAULT 15 level1_fixmap_pgt
5000 2 OBJECT GLOBAL DEFAULT 15 early_gdt_descr
5002 8 OBJECT LOCAL DEFAULT 15 early_gdt_descr_base
500a 8 OBJECT GLOBAL DEFAULT 15 phys_base
0000 8 OBJECT GLOBAL DEFAULT 17 initial_code
0008 8 OBJECT GLOBAL DEFAULT 17 initial_gs
0010 8 OBJECT GLOBAL DEFAULT 17 initial_stack
0000 4 OBJECT GLOBAL DEFAULT 19 early_recursion_flag
1000 4096 OBJECT GLOBAL DEFAULT 19 early_level4_pgt
2000 0x40000 OBJECT GLOBAL DEFAULT 19 early_dynamic_pgts
0000 4096 OBJECT GLOBAL DEFAULT 22 empty_zero_page
All have correct size and type.
Note, that we can now see that it might be worth pushing
early_recursion_flag after early_dynamic_pgts -- we are wasting almost
4K of .init.data.
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
---
arch/x86/kernel/head_32.S | 29 ++++++++-------
arch/x86/kernel/head_64.S | 78 +++++++++++++++++++++------------------
2 files changed, 58 insertions(+), 49 deletions(-)
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 0bae769b7b59..2d5390d84467 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -502,8 +502,7 @@ ENDPROC(early_ignore_irq)
__INITDATA
.align 4
-GLOBAL(early_recursion_flag)
- .long 0
+SYM_DATA(early_recursion_flag, .long 0)
__REFDATA
.align 4
@@ -551,7 +550,7 @@ EXPORT_SYMBOL(empty_zero_page)
__PAGE_ALIGNED_DATA
/* Page-aligned for the benefit of paravirt? */
.align PGD_ALIGN
-ENTRY(initial_page_table)
+SYM_DATA_START(initial_page_table)
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0 /* low identity map */
# if KPMDS == 3
.long pa(initial_pg_pmd+PGD_IDENT_ATTR),0
@@ -569,17 +568,18 @@ ENTRY(initial_page_table)
# error "Kernel PMDs should be 1, 2 or 3"
# endif
.align PAGE_SIZE /* needs to be page-sized too */
+SYM_DATA_END(initial_page_table)
#endif
.data
.balign 4
-ENTRY(initial_stack)
- /*
- * The SIZEOF_PTREGS gap is a convention which helps the in-kernel
- * unwinder reliably detect the end of the stack.
- */
- .long init_thread_union + THREAD_SIZE - SIZEOF_PTREGS - \
- TOP_OF_KERNEL_STACK_PADDING;
+/*
+ * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
+ * reliably detect the end of the stack.
+ */
+SYM_DATA(initial_stack,
+ .long init_thread_union + THREAD_SIZE -
+ SIZEOF_PTREGS - TOP_OF_KERNEL_STACK_PADDING)
__INITRODATA
int_msg:
@@ -600,22 +600,25 @@ int_msg:
ALIGN
# early boot GDT descriptor (must use 1:1 address mapping)
.word 0 # 32 bit align gdt_desc.address
-boot_gdt_descr:
+SYM_DATA_START(boot_gdt_descr)
.word __BOOT_DS+7
.long boot_gdt - __PAGE_OFFSET
+SYM_DATA_END(boot_gdt_descr)
# boot GDT descriptor (later on used by CPU#0):
.word 0 # 32 bit align gdt_desc.address
-ENTRY(early_gdt_descr)
+SYM_DATA_START(early_gdt_descr)
.word GDT_ENTRIES*8-1
.long gdt_page /* Overwritten for secondary CPUs */
+SYM_DATA_END(early_gdt_descr)
/*
* The boot_gdt must mirror the equivalent in setup.S and is
* used only for booting.
*/
.align L1_CACHE_BYTES
-ENTRY(boot_gdt)
+SYM_DATA_START(boot_gdt)
.fill GDT_ENTRY_BOOT_CS,8,0
.quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
.quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
+SYM_DATA_END(boot_gdt)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 6fedcda37634..6661c76a2049 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -260,16 +260,14 @@ END(start_cpu0)
/* Both SMP bootup and ACPI suspend change these variables */
__REFDATA
.balign 8
- GLOBAL(initial_code)
- .quad x86_64_start_kernel
- GLOBAL(initial_gs)
- .quad INIT_PER_CPU_VAR(fixed_percpu_data)
- GLOBAL(initial_stack)
- /*
- * The SIZEOF_PTREGS gap is a convention which helps the in-kernel
- * unwinder reliably detect the end of the stack.
- */
- .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS
+SYM_DATA(initial_code, .quad x86_64_start_kernel)
+SYM_DATA(initial_gs, .quad INIT_PER_CPU_VAR(fixed_percpu_data))
+/*
+ * The SIZEOF_PTREGS gap is a convention which helps the in-kernel unwinder
+ * reliably detect the end of the stack.
+ */
+SYM_DATA(initial_stack,
+ .quad init_thread_union + THREAD_SIZE - SIZEOF_PTREGS)
__FINITDATA
__INIT
@@ -338,12 +336,10 @@ SYM_CODE_END(early_idt_handler_common)
__INITDATA
.balign 4
-GLOBAL(early_recursion_flag)
- .long 0
+SYM_DATA(early_recursion_flag, .long 0)
-#define NEXT_PAGE(name) \
- .balign PAGE_SIZE; \
-GLOBAL(name)
+#define SYM_DATA_START_PAGE_ALIGNED(name) \
+ SYM_START(name, SYM_L_GLOBAL, .balign PAGE_SIZE)
#ifdef CONFIG_PAGE_TABLE_ISOLATION
/*
@@ -358,11 +354,11 @@ GLOBAL(name)
*/
#define PTI_USER_PGD_FILL 512
/* This ensures they are 8k-aligned: */
-#define NEXT_PGD_PAGE(name) \
- .balign 2 * PAGE_SIZE; \
-GLOBAL(name)
+#define SYM_DATA_START_PTI_ALIGNED(name) \
+ SYM_START(name, SYM_L_GLOBAL, .balign 2 * PAGE_SIZE)
#else
-#define NEXT_PGD_PAGE(name) NEXT_PAGE(name)
+#define SYM_DATA_START_PTI_ALIGNED(name) \
+ SYM_DATA_START_PAGE_ALIGNED(name)
#define PTI_USER_PGD_FILL 0
#endif
@@ -375,17 +371,19 @@ GLOBAL(name)
.endr
__INITDATA
-NEXT_PGD_PAGE(early_top_pgt)
+SYM_DATA_START_PTI_ALIGNED(early_top_pgt)
.fill 512,8,0
.fill PTI_USER_PGD_FILL,8,0
+SYM_DATA_END(early_top_pgt)
-NEXT_PAGE(early_dynamic_pgts)
+SYM_DATA_START_PAGE_ALIGNED(early_dynamic_pgts)
.fill 512*EARLY_DYNAMIC_PAGE_TABLES,8,0
+SYM_DATA_END(early_dynamic_pgts)
.data
#if defined(CONFIG_XEN_PV) || defined(CONFIG_PVH)
-NEXT_PGD_PAGE(init_top_pgt)
+SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
.org init_top_pgt + L4_PAGE_OFFSET*8, 0
.quad level3_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
@@ -393,11 +391,13 @@ NEXT_PGD_PAGE(init_top_pgt)
/* (2^48-(2*1024*1024*1024))/(2^39) = 511 */
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
.fill PTI_USER_PGD_FILL,8,0
+SYM_DATA_END(init_top_pgt)
-NEXT_PAGE(level3_ident_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level3_ident_pgt)
.quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
.fill 511, 8, 0
-NEXT_PAGE(level2_ident_pgt)
+SYM_DATA_END(level3_ident_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level2_ident_pgt)
/*
* Since I easily can, map the first 1G.
* Don't set NX because code runs from these pages.
@@ -407,25 +407,29 @@ NEXT_PAGE(level2_ident_pgt)
* the CPU should ignore the bit.
*/
PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD)
+SYM_DATA_END(level2_ident_pgt)
#else
-NEXT_PGD_PAGE(init_top_pgt)
+SYM_DATA_START_PTI_ALIGNED(init_top_pgt)
.fill 512,8,0
.fill PTI_USER_PGD_FILL,8,0
+SYM_DATA_END(init_top_pgt)
#endif
#ifdef CONFIG_X86_5LEVEL
-NEXT_PAGE(level4_kernel_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level4_kernel_pgt)
.fill 511,8,0
.quad level3_kernel_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
+SYM_DATA_END(level4_kernel_pgt)
#endif
-NEXT_PAGE(level3_kernel_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level3_kernel_pgt)
.fill L3_START_KERNEL,8,0
/* (2^48-(2*1024*1024*1024)-((2^39)*511))/(2^30) = 510 */
.quad level2_kernel_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC
.quad level2_fixmap_pgt - __START_KERNEL_map + _PAGE_TABLE_NOENC
+SYM_DATA_END(level3_kernel_pgt)
-NEXT_PAGE(level2_kernel_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level2_kernel_pgt)
/*
* 512 MB kernel mapping. We spend a full page on this pagetable
* anyway.
@@ -442,8 +446,9 @@ NEXT_PAGE(level2_kernel_pgt)
*/
PMDS(0, __PAGE_KERNEL_LARGE_EXEC,
KERNEL_IMAGE_SIZE/PMD_SIZE)
+SYM_DATA_END(level2_kernel_pgt)
-NEXT_PAGE(level2_fixmap_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level2_fixmap_pgt)
.fill (512 - 4 - FIXMAP_PMD_NUM),8,0
pgtno = 0
.rept (FIXMAP_PMD_NUM)
@@ -453,21 +458,21 @@ NEXT_PAGE(level2_fixmap_pgt)
.endr
/* 6 MB reserved space + a 2MB hole */
.fill 4,8,0
+SYM_DATA_END(level2_fixmap_pgt)
-NEXT_PAGE(level1_fixmap_pgt)
+SYM_DATA_START_PAGE_ALIGNED(level1_fixmap_pgt)
.rept (FIXMAP_PMD_NUM)
.fill 512,8,0
.endr
+SYM_DATA_END(level1_fixmap_pgt)
#undef PMDS
.data
.align 16
- .globl early_gdt_descr
-early_gdt_descr:
- .word GDT_ENTRIES*8-1
-early_gdt_descr_base:
- .quad INIT_PER_CPU_VAR(gdt_page)
+
+SYM_DATA(early_gdt_descr, .word GDT_ENTRIES*8-1)
+SYM_DATA_LOCAL(early_gdt_descr_base, .quad INIT_PER_CPU_VAR(gdt_page))
/* This must match the first entry in level2_kernel_pgt */
SYM_DATA(phys_base, .quad 0x0000000000000000)
@@ -476,7 +481,8 @@ EXPORT_SYMBOL(phys_base)
#include "../../x86/xen/xen-head.S"
__PAGE_ALIGNED_BSS
-NEXT_PAGE(empty_zero_page)
+SYM_DATA_START_PAGE_ALIGNED(empty_zero_page)
.skip PAGE_SIZE
+SYM_DATA_END(empty_zero_page)
EXPORT_SYMBOL(empty_zero_page)
--
2.22.0