diff options
| -rw-r--r-- | TODO | 4 | ||||
| -rw-r--r-- | src/biosvar.h | 5 | ||||
| -rw-r--r-- | src/output.c | 4 | ||||
| -rw-r--r-- | src/romlayout.S | 174 |
4 files changed, 100 insertions, 87 deletions
@@ -4,9 +4,7 @@ setup properly with respect to irqs. Audit statements where a 32bit intermediary changes meaning of a 16bit comparison. -Look into ways to reduce stack usage. For example, %esp, %ebp, %esi -(high bits), %edi (high bits) are already restored by the C code if -they're changed - they probably don't need to be backed up on entry. +Look into ways to reduce stack usage. Code assumes ebda segment is static - it doesn't read 0x40e. diff --git a/src/biosvar.h b/src/biosvar.h index 4def7f39..36794c38 100644 --- a/src/biosvar.h +++ b/src/biosvar.h @@ -287,13 +287,14 @@ struct ipl_s { #define UREG(ER, R, RH, RL) union { u32 ER; struct { u16 R; u16 R ## _hi; }; struct { u8 RL; u8 RH; u8 R ## _hilo; u8 R ## _hihi; }; } +// Layout of registers passed in to irq handlers. Note that this +// layout corresponds to code in romlayout.S - don't change it here +// without also updating the assembler code. struct bregs { u16 ds; u16 es; UREG(edi, di, di_hi, di_lo); UREG(esi, si, si_hi, si_lo); - UREG(ebp, bp, bp_hi, bp_lo); - UREG(esp, sp, sp_hi, sp_lo); UREG(ebx, bx, bh, bl); UREG(edx, dx, dh, dl); UREG(ecx, cx, ch, cl); diff --git a/src/output.c b/src/output.c index 760ea417..0336610e 100644 --- a/src/output.c +++ b/src/output.c @@ -178,8 +178,8 @@ dump_regs(const char *fname, const char *type, struct bregs *regs) bprintf(0, "%s %s: a=%x b=%x c=%x d=%x si=%x di=%x\n" , type, fname, regs->eax, regs->ebx, regs->ecx, regs->edx , regs->esi, regs->edi); - bprintf(0, " ds=%x es=%x bp=%x sp=%x ip=%x cs=%x f=%x\n" - , regs->ds, regs->es, regs->ebp, regs->esp + bprintf(0, " ds=%x es=%x ip=%x cs=%x f=%x\n" + , regs->ds, regs->es , regs->ip, regs->cs, regs->flags); } diff --git a/src/romlayout.S b/src/romlayout.S index d5253457..2fd0f839 100644 --- a/src/romlayout.S +++ b/src/romlayout.S @@ -27,9 +27,58 @@ bios16c_end: /**************************************************************** - * POST handler + * Entry macros ****************************************************************/ + // Call a C function - this does the minimal work necessary to + // call into C. It sets up %ds, backs up %es, and backs up + // those registers that are call clobbered by the C compiler. + .macro ENTRY cfunc + cld + pushl %eax + pushl %ecx + pushl %edx + pushw %es + pushw %ds + movw %ss, %ax + movw %ax, %ds + calll \cfunc + popw %ds + popw %es + popl %edx + popl %ecx + popl %eax + .endm + + // Call a C function with current register list as an + // argument. This backs up the registers and sets %eax + // to point to the backup. On return, the registers are + // restored from the structure. + .macro ENTRY_ARG cfunc + cld + pushl %eax + pushl %ecx + pushl %edx + pushl %ebx + pushl %esi + pushl %edi + pushw %es + pushw %ds + movw %ss, %ax + movw %ax, %ds + movzwl %sp, %esp + movl %esp, %eax + calll \cfunc + popw %ds + popw %es + popl %edi + popl %esi + popl %ebx + popl %edx + popl %ecx + popl %eax + .endm + // Macro to reset the 16bit stack // Clobbers %ax .macro RESET_STACK @@ -38,6 +87,11 @@ bios16c_end: movl $ CONFIG_STACK_OFFSET , %esp .endm + +/**************************************************************** + * POST handler + ****************************************************************/ + .org 0xe05b .globl post16 post16: @@ -153,18 +207,17 @@ __call16: // Setup for iretw call pushw $0xf000 pushw $1f // return point - pushw 0x28(%eax) // flags - pushl 0x24(%eax) // CS:IP + pushw 0x20(%eax) // flags + pushl 0x1c(%eax) // CS:IP // Load calling registers. movl 0x04(%eax), %edi movl 0x08(%eax), %esi - movl 0x0c(%eax), %ebp - movl 0x14(%eax), %ebx - movl 0x18(%eax), %edx - movl 0x1c(%eax), %ecx + movl 0x0c(%eax), %ebx + movl 0x10(%eax), %edx + movl 0x14(%eax), %ecx movw 0x02(%eax), %es // XXX - should load %ds too - movl 0x20(%eax), %eax + movl 0x18(%eax), %eax // Invoke call iretw // XXX - just do a lcalll @@ -173,21 +226,20 @@ __call16: pushfw pushl %eax movl 0x06(%esp), %eax - movl %ecx, %ss:0x1c(%eax) // Save %ecx + movl %ecx, %ss:0x14(%eax) // Save %ecx movw %ss, %cx movw %cx, %ds // Restore %ds == %ss popl %ecx - movl %ecx, 0x20(%eax) // Save %eax + movl %ecx, 0x18(%eax) // Save %eax popw %cx - movw %cx, 0x28(%eax) // Save flags + movw %cx, 0x20(%eax) // Save flags // Store remaining registers movw %es, 0x02(%eax) movl %edi, 0x04(%eax) movl %esi, 0x08(%eax) - movl %ebp, 0x0c(%eax) - movl %ebx, 0x14(%eax) - movl %edx, 0x18(%eax) + movl %ebx, 0x0c(%eax) + movl %edx, 0x10(%eax) // Remove %eax popl %eax @@ -196,6 +248,32 @@ __call16: retl + // APM trampolines + .globl apm16protected_entry +apm16protected_entry: + pushfw // save flags + pushl %eax // dummy + ENTRY_ARG handle_1553 + addw $4, %sp // pop dummy + popfw // restore flags + lretw + + .code32 + .globl apm32protected_entry +apm32protected_entry: + pushfw // save flags + pushw %cs // Setup for long jump to 16bitmode + incw (%esp) + pushw 1f + lcallw *(%esp) + addl $4, %esp // pop call address + popfw + lretl + .code16gcc +1: // 16bit entry point for apm32 code. + ENTRY_ARG handle_1553 + lretw + /**************************************************************** * GDT and IDT tables @@ -246,45 +324,6 @@ rombios32_gdt: * Interrupt entry points ****************************************************************/ - // Call a C function - this does the minimal work necessary to - // call into C. It sets up %ds, backs up %es, and backs up - // those registers that are call clobbered by the C compiler. - .macro ENTRY cfunc - cld - pushl %eax - pushl %ecx - pushl %edx - pushw %es - pushw %ds - movw %ss, %ax - movw %ax, %ds - calll \cfunc - popw %ds - popw %es - popl %edx - popl %ecx - popl %eax - .endm - - // Call a C function with current register list as an - // argument. This backs up the registers and sets %eax - // to point to the backup. On return, the registers are - // restored from the structur. - .macro ENTRY_ARG cfunc - cld - pushal - pushw %es - pushw %ds - movw %ss, %ax - movw %ax, %ds - movzwl %sp, %esp - movl %esp, %eax - calll \cfunc - popw %ds - popw %es - popal - .endm - // Define an entry point for an interrupt (no args passed). .macro IRQ_ENTRY num .globl entry_\num @@ -303,32 +342,6 @@ rombios32_gdt: iretw .endm - // APM trampolines - .globl apm16protected_entry -apm16protected_entry: - pushfw // save flags - pushl %eax // dummy - ENTRY_ARG handle_1553 - addw $4, %sp // pop dummy - popfw // restore flags - lretw - - .code32 - .globl apm32protected_entry -apm32protected_entry: - pushfw // save flags - pushw %cs // Setup for long jump to 16bitmode - incw (%esp) - pushw 1f - lcallw *(%esp) - addl $4, %esp // pop call address - popfw - lretl - .code16gcc -1: // 16bit entry point for apm32 code. - ENTRY_ARG handle_1553 - lretw - .org 0xe2c3 IRQ_ENTRY nmi @@ -339,7 +352,6 @@ apm32protected_entry: IRQ_ENTRY 1c IRQ_ENTRY 70 IRQ_ENTRY 74 - IRQ_ENTRY 75 .org 0xe3fe jmp entry_13 @@ -360,6 +372,8 @@ apm32protected_entry: .org 0xe739 IRQ_ENTRY_ARG 14 + IRQ_ENTRY 75 + // int 18/19 are special - they reset the stack and do not return. .globl entry_19 entry_19: |