3 files changed, 43 insertions, 18 deletions
diff --git a/src/kernel/arch/amd64/interrupts.h b/src/kernel/arch/amd64/interrupts.h
index 288bd78..f968906 100644
--- a/src/kernel/arch/amd64/interrupts.h
+++ b/src/kernel/arch/amd64/interrupts.h
@@ -11,7 +11,8 @@
 
 extern void (*irq_fn[16])(void);
 extern const char _isr_stubs;
+struct IsrFrame;
 
 void irq_init(void);
 void irq_eoi(uint8_t line);
-void isr_stage3(uint8_t interrupt, void *stackframe);
+void isr_stage3(uint8_t interrupt, struct IsrFrame *stackframe);
diff --git a/src/kernel/arch/amd64/interrupts/isr.c b/src/kernel/arch/amd64/interrupts/isr.c
index bf84c5c..15993b2 100644
--- a/src/kernel/arch/amd64/interrupts/isr.c
+++ b/src/kernel/arch/amd64/interrupts/isr.c
@@ -19,6 +19,13 @@ typedef struct {
 	uint64_t sp, ss;
 } IretFrame;
 
+typedef struct IsrFrame {
+	UserRegs regs; /* doesn't include ip, flags, sp */
+	uint64_t _retaddr;
+	uint64_t errcode;
+	IretFrame iret;
+} __attribute__((packed)) IsrFrame;
+
 void (*irq_fn[16])(void) = {0};
 
 static uint64_t
@@ -30,12 +37,11 @@ getcr2(void)
 }
 
 static void
-log_interrupt(uint8_t inr, void *stackframe)
+log_interrupt(uint8_t inr, IsrFrame *sf)
 {
-	IretFrame *iret = stackframe;
-	uint64_t *errcode = ((uint64_t*)stackframe) - 1;
+	IretFrame *iret = &sf->iret;
 	kprintf("interrupt %d, rip = k/%08x, cs 0x%x, code 0x%x\n",
-			inr, iret->ip, iret->cs, *errcode);
+			inr, iret->ip, iret->cs, sf->errcode);
 	if ((iret->cs & 0x3) == 0) { /* ring 0? */
 		uint64_t *stack = (void*)iret->sp;
 		kprintf("kernel rsp = %p, *rsp = %p\n", stack, *stack);
@@ -46,9 +52,9 @@ log_interrupt(uint8_t inr, void *stackframe)
 }
 
 void
-isr_stage3(uint8_t inr, void *stackframe)
+isr_stage3(uint8_t inr, IsrFrame *sf)
 {
-	IretFrame *iret = stackframe;
+	IretFrame *iret = &sf->iret;
 	uint8_t irqn = inr - IRQ_IBASE;
 	if (irqn < 16) {
 		if (irq_fn[irqn]) {
@@ -59,13 +65,13 @@ isr_stage3(uint8_t inr, void *stackframe)
 	}
 
 	if (inr == Nmi) { /* print some debugging information */
-		log_interrupt(inr, stackframe);
+		log_interrupt(inr, sf);
 		mem_debugprint();
 		return;
 	}
 
 	if ((iret->cs & 0x3) == 0) { /* ring 0? */
-		log_interrupt(inr, stackframe);
+		log_interrupt(inr, sf);
 		cpu_halt();
 	} else { /* in user */
 		proc_kill(proc_cur, inr);
diff --git a/src/kernel/arch/amd64/interrupts/isr_stub.s b/src/kernel/arch/amd64/interrupts/isr_stub.s
index 3134808..5604f19 100644
--- a/src/kernel/arch/amd64/interrupts/isr_stub.s
+++ b/src/kernel/arch/amd64/interrupts/isr_stub.s
@@ -22,18 +22,27 @@ _isr_stubs:
 .endr
 
 _isr_stage2:
-	/* pushal order, without %esp. 15 in total */
+	/* UserRegs */
+	/* I'm skipping fields that are in the IRET stack frame
+	 * on the assumption it's easier to deal with them from C. */
+	push $0 /* flags */
+	push $0 /* ip */
+
 	push %rax
 	push %rcx
 	push %rdx
 	push %rbx
+
+	push $0 /* rsp */
 	push %rbp
 	push %rsi
 	push %rdi
+
 	push %r8
 	push %r9
 	push %r10
 	push %r11
+
 	push %r12
 	push %r13
 	push %r14
@@ -45,15 +54,15 @@ _isr_stage2:
 	// basically if you're context switching, FXSAVE
 
 	/* first argument: vector nr. computed from the return address at offset
-	 * 15*8 = 120 */
-	mov 120(%rsp), %rdi
+	 * 18*8 = 144 */
+	mov 144(%rsp), %rdi
 	sub $_isr_stubs, %rdi
 	shr $3, %rdi
 
-	/* second argument: IRET stack frame */
-	lea 136(%rsp), %rsi
+	/* second argument: stack frame */
+	mov %rsp, %rsi
 
-	// load kernel paging
+	/* load kernel paging */
 	mov %cr3, %rbx
 	push %rbx
 	mov $pml4_identity, %rbx
@@ -64,27 +73,36 @@ _isr_stage2:
 	call isr_stage3
 
 	mov %rbp, %rsp
-	pop %rax // restore old cr3
+	pop %rax /* restore old cr3 */
 	mov %rax, %cr3
 
-	// restore registers
+	/* restore registers */
 	pop %r15
 	pop %r14
 	pop %r13
 	pop %r12
+
 	pop %r11
 	pop %r10
 	pop %r9
 	pop %r8
+
 	pop %rdi
 	pop %rsi
 	pop %rbp
+	pop %rbx /* skip rsp */
+
 	pop %rbx
 	pop %rdx
 	pop %rcx
 	pop %rax
 
-	add $16, %rsp /* skip return address from call and the error code */
+	/* skips:
+	 *  UserRegs.ip
+	 *  UserRegs.flags
+	 *  return address from the CALL in the stub
+	 *  error code */
+	add $32, %rsp
 	iretq
 
 .align 8