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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/boot: Drop sym_fs()
commit 021cc01ecac111be3301ad33ff5cda4543ca8b92
Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Jan 9 14:06:38 2020 +0000
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed Jan 22 19:03:18 2020 +0000
x86/boot: Drop sym_fs()
All remaining users of sym_fs() can trivially be switched to using sym_esi()
instead. This is shorter to encode and faster to execute.
This removes the final uses of %fs during boot, which allows us to drop
BOOT_FS from the trampoline GDT, which drops an 16M arbitrary limit on Xen's
compiled size.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
xen/arch/x86/boot/head.S | 41 ++++++++++++++---------------------------
xen/arch/x86/boot/trampoline.S | 1 -
2 files changed, 14 insertions(+), 28 deletions(-)
diff --git a/xen/arch/x86/boot/head.S b/xen/arch/x86/boot/head.S
index bd18ad48e5..153a53f250 100644
--- a/xen/arch/x86/boot/head.S
+++ b/xen/arch/x86/boot/head.S
@@ -14,14 +14,12 @@
#define sym_offs(sym) ((sym) - __XEN_VIRT_START)
#define sym_esi(sym) sym_offs(sym)(%esi)
-#define sym_fs(sym) %fs:sym_offs(sym)
#define BOOT_CS32 0x0008
#define BOOT_CS64 0x0010
#define BOOT_DS 0x0018
#define BOOT_PSEUDORM_CS 0x0020
#define BOOT_PSEUDORM_DS 0x0028
-#define BOOT_FS 0x0030
#define MB2_HT(name) (MULTIBOOT2_HEADER_TAG_##name)
#define MB2_TT(name) (MULTIBOOT2_TAG_TYPE_##name)
@@ -555,24 +553,13 @@ trampoline_bios_setup:
trampoline_setup:
/*
* Called on legacy BIOS and EFI platforms.
- *
- * Set the BOOT_FS descriptor base address to %esi.
*/
- mov %esi, %edx
- shr $16, %edx
- mov %si, BOOT_FS + 2 + sym_esi(trampoline_gdt) /* Bits 0-15 */
- mov %dl, BOOT_FS + 4 + sym_esi(trampoline_gdt) /* Bits 16-23 */
- mov %dh, BOOT_FS + 7 + sym_esi(trampoline_gdt) /* Bits 24-31 */
-
- /* Load %fs to allow for access to Xen data. */
- mov $BOOT_FS, %edx
- mov %edx, %fs
/* Save Xen image load base address for later use. */
- mov %esi,sym_fs(xen_phys_start)
- mov %esi,sym_fs(trampoline_xen_phys_start)
+ mov %esi, sym_esi(xen_phys_start)
+ mov %esi, sym_esi(trampoline_xen_phys_start)
- mov sym_fs(trampoline_phys),%ecx
+ mov sym_esi(trampoline_phys), %ecx
/* Get bottom-most low-memory stack address. */
add $TRAMPOLINE_SPACE,%ecx
@@ -583,13 +570,13 @@ trampoline_setup:
push %eax /* Magic number. */
call reloc
#ifdef CONFIG_PVH_GUEST
- cmpb $0, sym_fs(pvh_boot)
+ cmpb $0, sym_esi(pvh_boot)
je 1f
- mov %eax, sym_fs(pvh_start_info_pa)
+ mov %eax, sym_esi(pvh_start_info_pa)
jmp 2f
#endif
1:
- mov %eax, sym_fs(multiboot_ptr)
+ mov %eax, sym_esi(multiboot_ptr)
2:
/*
@@ -613,7 +600,7 @@ trampoline_setup:
* Do not zero BSS on EFI platform here.
* It was initialized earlier.
*/
- cmpb $0,sym_fs(efi_platform)
+ cmpb $0, sym_esi(efi_platform)
jnz 1f
/*
@@ -632,7 +619,7 @@ trampoline_setup:
/* Interrogate CPU extended features via CPUID. */
mov $1, %eax
cpuid
- mov %ecx, sym_fs(boot_cpu_data) +
CPUINFO_FEATURE_OFFSET(X86_FEATURE_HYPERVISOR)
+ mov %ecx, CPUINFO_FEATURE_OFFSET(X86_FEATURE_HYPERVISOR) +
sym_esi(boot_cpu_data)
mov $0x80000000,%eax
cpuid
@@ -644,7 +631,7 @@ trampoline_setup:
jbe 1f
mov $0x80000001,%eax
cpuid
-1: mov %edx, sym_fs(boot_cpu_data) +
CPUINFO_FEATURE_OFFSET(X86_FEATURE_LM)
+1: mov %edx, CPUINFO_FEATURE_OFFSET(X86_FEATURE_LM) +
sym_esi(boot_cpu_data)
/* Check for NX. Adjust EFER setting if available. */
bt $cpufeat_bit(X86_FEATURE_NX), %edx
@@ -658,8 +645,8 @@ trampoline_setup:
/* Stash TSC to calculate a good approximation of time-since-boot */
rdtsc
- mov %eax,sym_fs(boot_tsc_stamp)
- mov %edx,sym_fs(boot_tsc_stamp)+4
+ mov %eax, sym_esi(boot_tsc_stamp)
+ mov %edx, 4 + sym_esi(boot_tsc_stamp)
/* Relocate pagetables to point at Xen's current location in memory. */
mov $_PAGE_PRESENT, %edx
@@ -752,11 +739,11 @@ trampoline_setup:
jb 1b
/* Do not parse command line on EFI platform here. */
- cmpb $0,sym_fs(efi_platform)
+ cmpb $0, sym_esi(efi_platform)
jnz 1f
/* Bail if there is no command line to parse. */
- mov sym_fs(multiboot_ptr),%ebx
+ mov sym_esi(multiboot_ptr), %ebx
testl $MBI_CMDLINE,MB_flags(%ebx)
jz 1f
@@ -767,7 +754,7 @@ trampoline_setup:
1:
/* Switch to low-memory stack which lives at the end of trampoline
region. */
- mov sym_fs(trampoline_phys),%edi
+ mov sym_esi(trampoline_phys), %edi
lea TRAMPOLINE_SPACE+TRAMPOLINE_STACK_SPACE(%edi),%esp
lea trampoline_boot_cpu_entry-trampoline_start(%edi),%eax
pushl $BOOT_CS32
diff --git a/xen/arch/x86/boot/trampoline.S b/xen/arch/x86/boot/trampoline.S
index 6b403a6d1a..18c6638924 100644
--- a/xen/arch/x86/boot/trampoline.S
+++ b/xen/arch/x86/boot/trampoline.S
@@ -129,7 +129,6 @@ gdt_48:
.quad 0x00cf93000000ffff /* 0x0018: ring 0 data */
.quad 0x00009b000000ffff /* 0x0020: real-mode code @ BOOT_TRAMPOLINE
*/
.quad 0x000093000000ffff /* 0x0028: real-mode data @ BOOT_TRAMPOLINE
*/
- .quad 0x00c0930000000fff /* 0x0030: ring 0 Xen data, 16M @ XEN */
.Ltrampoline_gdt_end:
/* Relocations for trampoline Real Mode segments. */
--
generated by git-patchbot for /home/xen/git/xen.git#master
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