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| author | Michael Brown | 2006-05-06 20:52:27 +0200 |
|---|---|---|
| committer | Michael Brown | 2006-05-06 20:52:27 +0200 |
| commit | c10d1aa9d7096db706c94a2b0d66b4f8357416e7 (patch) | |
| tree | b7717f68dbc2e2859989c00bb682f5a794c917c4 /src | |
| parent | This line should not have been checked in (diff) | |
| download | ipxe-c10d1aa9d7096db706c94a2b0d66b4f8357416e7.tar.gz ipxe-c10d1aa9d7096db706c94a2b0d66b4f8357416e7.tar.xz ipxe-c10d1aa9d7096db706c94a2b0d66b4f8357416e7.zip | |
Preserve GDT across prot_call().
Diffstat (limited to 'src')
| -rw-r--r-- | src/arch/i386/transitions/librm.S | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/src/arch/i386/transitions/librm.S b/src/arch/i386/transitions/librm.S index 46b545e8..331e6215 100644 --- a/src/arch/i386/transitions/librm.S +++ b/src/arch/i386/transitions/librm.S @@ -335,7 +335,8 @@ rm_ds: .word 0 **************************************************************************** */ -#define PC_OFFSET_IX86 ( 0 ) +#define PC_OFFSET_GDT ( 0 ) +#define PC_OFFSET_IX86 ( PC_OFFSET_GDT + 8 /* pad to 8 to keep alignment */ ) #define PC_OFFSET_RETADDR ( PC_OFFSET_IX86 + SIZEOF_I386_ALL_REGS ) #define PC_OFFSET_FUNCTION ( PC_OFFSET_RETADDR + 4 ) #define PC_OFFSET_END ( PC_OFFSET_FUNCTION + 4 ) @@ -344,7 +345,7 @@ rm_ds: .word 0 .code16 .globl prot_call prot_call: - /* Preserve registers and flags on external RM stack */ + /* Preserve registers, flags and GDT on external RM stack */ pushfl pushal pushw %gs @@ -353,6 +354,9 @@ prot_call: pushw %ds pushw %ss pushw %cs + subw $8, %sp + movw %sp, %bp + sgdt (%bp) /* For sanity's sake, clear the direction flag as soon as possible */ cld @@ -368,7 +372,8 @@ prot_call: call gateA20_set /* Call function */ - pushl %esp + leal PC_OFFSET_IX86(%esp), %eax + pushl %eax call *(PC_OFFSET_FUNCTION+4)(%esp) popl %eax /* discard */ @@ -379,9 +384,10 @@ prot_call: .section ".text16" .code16 1: - /* Restore registers and flags and return */ - popw %ax /* skip %cs - it is already set */ - popw %ax /* skip %ss - it is already set */ + /* Reload GDT, restore registers and flags and return */ + movw %sp, %bp + lgdt (%bp) + addw $12, %sp /* also skip %cs and %ss */ popw %ds popw %es popw %fs |