[PATCH v3 1/3] x86/boot: Drop pre-C IDT patching

[Andrew Cooper <andrew.cooper3@citrix.com>]

It is not needed now that __start_xen sets itself up with complete trap
handlers as its first action.  This fixes a potential issue introduced in

  c/s 7e510a7b874
  "x86/boot: move some __high_start code and data into init sections"

which would leave ignore_int (in the .init section) patched into the reserved
exceptions in all IDTs.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <JBeulich@suse.com>
CC: Tim Deegan <tim@xen.org>
---
 xen/arch/x86/boot/x86_64.S |   56 +-------------------------------------------
 xen/arch/x86/efi/boot.c    |    1 -
 2 files changed, 1 insertion(+), 56 deletions(-)

diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index 417623f..bfbafd2 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -25,64 +25,15 @@
         leaq    1f(%rip),%rax
         pushq   %rax
         lretq
-1:      lidt    idt_descr(%rip)
-
+1:
         test    %ebx,%ebx
         jnz     start_secondary
-        jmp     start_bsp
-
-        .section .init.text, "ax", @progbits
-
-start_bsp:
-        /* Initialise IDT with simple error defaults. */
-        leaq    ignore_int(%rip),%rcx
-        movl    %ecx,%eax
-        andl    $0xFFFF0000,%eax
-        orl     $0x00008E00,%eax
-        shlq    $32,%rax
-        movl    %ecx,%edx
-        andl    $0x0000FFFF,%edx
-        orl     $(__HYPERVISOR_CS64<<16),%edx
-        orq     %rdx,%rax
-        shrq    $32,%rcx
-        movl    %ecx,%edx
-        leaq    idt_table(%rip),%rdi
-        movl    $256,%ecx
-1:      movq    %rax,(%rdi)
-        movq    %rdx,8(%rdi)
-        addq    $16,%rdi
-        loop    1b
 
         /* Pass off the Multiboot info structure to C land. */
         mov     multiboot_ptr(%rip),%edi
         call    __start_xen
         ud2     /* Force a panic (invalid opcode). */
 
-/* This is the default interrupt handler. */
-ignore_int:
-        SAVE_ALL CLAC
-        movq    %cr2,%rsi
-        leaq    int_msg(%rip),%rdi
-        xorl    %eax,%eax
-        call    printk
-        movq    %rsp,%rbp
-0:      movq    (%rbp),%rsi
-        addq    $8,%rbp
-        leaq    hex_msg(%rip),%rdi
-        xorl    %eax,%eax
-        call    printk
-        testq   $0xff8,%rbp
-        jnz     0b
-1:      hlt
-        jmp     1b
-
-        .section .init.rodata, "a", @progbits
-
-int_msg:
-        .asciz "Unknown interrupt (cr2=%016lx)\n"
-hex_msg:
-        .asciz "    %016lx"
-
 /*** DESCRIPTOR TABLES ***/
 
         .data
@@ -95,11 +46,6 @@ GLOBAL(gdt_descr)
         .word   LAST_RESERVED_GDT_BYTE
         .quad   boot_cpu_gdt_table - FIRST_RESERVED_GDT_BYTE
 
-        .word   0,0,0
-GLOBAL(idt_descr)
-        .word   256*16-1
-        .quad   idt_table
-
 GLOBAL(stack_start)
         .quad   cpu0_stack
 
diff --git a/xen/arch/x86/efi/boot.c b/xen/arch/x86/efi/boot.c
index 62c4812..a772509 100644
--- a/xen/arch/x86/efi/boot.c
+++ b/xen/arch/x86/efi/boot.c
@@ -1474,7 +1474,6 @@ efi_start(EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable)
     asm volatile ( "mov    %[cr4], %%cr4\n\t"
                    "mov    %[cr3], %%cr3\n\t"
                    "movabs $__start_xen, %[rip]\n\t"
-                   "lidt   idt_descr(%%rip)\n\t"
                    "lgdt   gdt_descr(%%rip)\n\t"
                    "mov    stack_start(%%rip), %%rsp\n\t"
                    "mov    %[ds], %%ss\n\t"
-- 
1.7.10.4