From: Jian Luo <[email protected]> PCI option rom may use different SS during its execution, so it is not safe to assume esp pointed to the same location in the protected mode.
Signed-off-by: Jian Luo <[email protected]> Signed-off-by: Bin Meng <[email protected]> --- Changes in v2 respin: - Use *protected* mode instead of 'protect mode' - Correct typo of 'read mode' Changes in v2: - Add comments for the changes in the assembly codes arch/x86/lib/bios_asm.S | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/lib/bios_asm.S b/arch/x86/lib/bios_asm.S index 4faa70e..9dbf969 100644 --- a/arch/x86/lib/bios_asm.S +++ b/arch/x86/lib/bios_asm.S @@ -246,6 +246,9 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) push %fs push %gs + /* Save real mode SS */ + movw %ss, %cs:__realmode_ss + /* Clear DF to not break ABI assumptions */ cld @@ -258,12 +261,29 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) enter_protected_mode + /* + * Now we are in protected mode. We need compute the right ESP based + * on saved real mode SS otherwise interrupt_handler() won't get + * correct parameters from the stack. + */ + movzwl %cs:__realmode_ss, %ecx + shll $4, %ecx + addl %ecx, %esp + /* Call the C interrupt handler */ movl $interrupt_handler, %eax call *%eax + /* Restore real mode ESP based on saved SS */ + movzwl %cs:__realmode_ss, %ecx + shll $4, %ecx + subl %ecx, %esp + enter_real_mode + /* Restore real mode SS */ + movw %cs:__realmode_ss, %ss + /* * Restore all registers, including those manipulated by the C * handler @@ -276,6 +296,9 @@ __interrupt_handler_16bit = PTR_TO_REAL_MODE(.) popal iret +__realmode_ss = PTR_TO_REAL_MODE(.) + .word 0 + .globl asm_realmode_code_size asm_realmode_code_size: .long . - asm_realmode_code -- 1.8.2.1 _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
