67 lines
2.4 KiB
Diff
67 lines
2.4 KiB
Diff
From: Kevin O'Connor <kevin@koconnor.net>
|
|
Date: Wed Feb 5 22:47:29 2014 -0500
|
|
Subject: vgabios: Attempt to detect old x86emu and force a fault.
|
|
Upstream-Commit: 8032b8a0fec550de5cb2f7d37aa031cebc2200c3
|
|
Bug-Debian: http://bugs.debian.org/737142
|
|
|
|
Check for cases where the leal instruction does not work. This
|
|
instruction is known to not be emulated properly on old versions of
|
|
x86emu. If a broken version of x86emu is found, force a fault that
|
|
x86emu will easily detect. This should help prevent soft failures
|
|
when running old software.
|
|
|
|
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
|
|
|
|
diff --git a/vgasrc/vgaentry.S b/vgasrc/vgaentry.S
|
|
index 9854448..6e31c4e 100644
|
|
--- a/vgasrc/vgaentry.S
|
|
+++ b/vgasrc/vgaentry.S
|
|
@@ -45,9 +45,26 @@ _rom_header_signature:
|
|
* Entry points
|
|
****************************************************************/
|
|
|
|
- // This macro is the same as ENTRY_ARG except the "calll"
|
|
- // instruction is avoided to work around known issues in the
|
|
- // emulation of some versions of x86emu.
|
|
+ // Force a fault if found to be running on broken x86emu versions.
|
|
+ DECLFUNC x86emu_fault
|
|
+x86emu_fault:
|
|
+1: hlt
|
|
+ jmp 1b
|
|
+
|
|
+ // This macro implements a call while avoiding instructions
|
|
+ // that old versions of x86emu have problems with.
|
|
+ .macro VGA_CALLL cfunc
|
|
+ // Make sure leal instruction works.
|
|
+ movl $0x8000, %ecx
|
|
+ leal (%ecx, %ecx, 1), %ecx
|
|
+ cmpl $0x10000, %ecx
|
|
+ jne x86emu_fault
|
|
+ // Use callw instead of calll
|
|
+ push %ax
|
|
+ callw \cfunc
|
|
+ .endm
|
|
+
|
|
+ // This macro is the same as ENTRY_ARG except VGA_CALLL is used.
|
|
.macro ENTRY_ARG_VGA cfunc
|
|
cli
|
|
cld
|
|
@@ -57,7 +74,7 @@ _rom_header_signature:
|
|
movl %esp, %ebx // Backup %esp, then zero high bits
|
|
movzwl %sp, %esp
|
|
movl %esp, %eax // First arg is pointer to struct bregs
|
|
- pushw %ax ; callw \cfunc
|
|
+ VGA_CALLL \cfunc
|
|
movl %ebx, %esp // Restore %esp (including high bits)
|
|
POPBREGS
|
|
.endm
|
|
@@ -103,7 +120,7 @@ entry_10_extrastack:
|
|
movw %ds, %dx // Setup %ss/%esp and call function
|
|
movw %dx, %ss
|
|
movl %eax, %esp
|
|
- pushw %ax ; callw handle_10
|
|
+ VGA_CALLL handle_10
|
|
|
|
movl %esp, %eax // Restore registers and return
|
|
movw BREGS_size+4(%eax), %ss
|