diff options
| -rw-r--r-- | src/arch/x86/prefix/libprefix.S | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/src/arch/x86/prefix/libprefix.S b/src/arch/x86/prefix/libprefix.S index ffb2110..d7f2619 100644 --- a/src/arch/x86/prefix/libprefix.S +++ b/src/arch/x86/prefix/libprefix.S @@ -380,6 +380,11 @@ process_bytes: pushl %eax pushl %ebp + /* Construct ljmp code on stack (since .prefix may not be writable) */ + .equ LJMP_LEN, 0x06 + pushw %cs /* "nop ; ljmp %cs, $2f" */ + pushw $2f + pushw $0xea90 /* Construct GDT on stack (since .prefix may not be writable) */ .equ GDT_LEN, 0x20 .equ PM_DS, 0x18 /* Flat data segment */ @@ -410,8 +415,9 @@ process_bytes: pushw %es pushw %ds pushw %ss - pushw %cs - pushw $2f + pushw %ss /* Far pointer to ljmp code on stack */ + leaw (GDT_LEN + 1)(%bp), %ax + pushw %ax cli data32 lgdt (%bp) movl %cr0, %eax @@ -438,7 +444,7 @@ process_bytes: popfw movl %eax, %cr0 lret -2: /* lret will ljmp to here */ +2: /* lret will ljmp to here (via constructed ljmp on stack) */ popw %ss popw %ds popw %es @@ -461,7 +467,7 @@ process_bytes: /* Restore GDT */ data32 lgdt -8(%bp) - leaw GDT_LEN(%bp), %sp + leaw (GDT_LEN + LJMP_LEN)(%bp), %sp /* Restore registers and return */ popl %ebp |