From 97314ab115206137018b0cd7196ce404ceee136c Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sun, 27 Nov 2022 21:28:32 +0100
Subject: Update kdb_kintr according to new interrupt stack layout

e2fcf261076b ("interrupt: Fix saving irq/ipl when linux drivers are
disabled") changed the stack layout for interrupt handlers, but missed
updating kdb_kintr's code that tries to mangle it.

This restores the control-alt-d shortcut.
---
 i386/i386/locore.S      | 14 ++++++++++----
 i386/i386at/interrupt.S |  2 ++
 x86_64/interrupt.S      |  2 ++
 x86_64/locore.S         |  8 ++++++--
 4 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/i386/i386/locore.S b/i386/i386/locore.S
index 162bb13a..922e3d87 100644
--- a/i386/i386/locore.S
+++ b/i386/i386/locore.S
@@ -793,9 +793,13 @@ ast_from_interrupt:
  * frame->	saved %ebp
  *		return address in interrupt handler
  * #ifndef MACH_XEN
- *		iunit
+ *		1st parameter iunit
+ *		2nd parameter saved SPL
+ *		3rd parameter irq
+ *		4th parameter return address
+ *		5th parameter registers
  *		saved SPL
- *		irq
+ *		saved IRQ
  * #endif
  *		return address == return_to_iret_i
  *		saved %edx
@@ -834,7 +838,7 @@ ast_from_interrupt:
 #ifdef	MACH_XEN
 #define	RET_OFFSET	8
 #else	/* MACH_XEN */
-#define	RET_OFFSET	20
+#define	RET_OFFSET	36
 #endif	/* MACH_XEN */
 
 ENTRY(kdb_kintr)
@@ -848,7 +852,9 @@ ENTRY(kdb_kintr)
 	cmpl	RET_OFFSET(%eax),%edx	/* interrupt handler (2)? */
 	je	2f			/* if not: */
 	movl	(%eax),%eax		/* try next frame */
-	jmp	0b
+	testl	%eax,%eax
+	jnz	0b
+	ud2				/* oops, didn't find frame, fix me :/ */
 
 1:	movl	$kdb_from_iret,RET_OFFSET(%eax)
 	ret				/* returns to kernel/user stack */
diff --git a/i386/i386at/interrupt.S b/i386/i386at/interrupt.S
index 7480fba9..167e02c8 100644
--- a/i386/i386at/interrupt.S
+++ b/i386/i386at/interrupt.S
@@ -29,6 +29,8 @@
  * Generic interrupt handler.
  *
  * On entry, %eax contains the irq number.
+ *
+ * Note: kdb_kintr needs to know our stack usage
  */
 
 #define S_REGS 32(%esp)
diff --git a/x86_64/interrupt.S b/x86_64/interrupt.S
index 56cd771b..110a429c 100644
--- a/x86_64/interrupt.S
+++ b/x86_64/interrupt.S
@@ -29,6 +29,8 @@
  * Generic interrupt handler.
  *
  * On entry, %eax contains the irq number.
+ *
+ * Note: kdb_kintr needs to know our stack usage
  */
 
 #define S_REGS 24(%rsp)
diff --git a/x86_64/locore.S b/x86_64/locore.S
index f677aed1..0833da06 100644
--- a/x86_64/locore.S
+++ b/x86_64/locore.S
@@ -839,6 +839,8 @@ ast_from_interrupt:
  *
  * frame->	saved %rbp
  *		return address in interrupt handler
+ *		saved SPL
+ *		saved IRQ
  *		return address == return_to_iret_i
  *		saved %r11
  *		saved %r10
@@ -878,7 +880,7 @@ ast_from_interrupt:
  * Call kdb, passing it that register save area.
  */
 
-#define	RET_OFFSET	16
+#define	RET_OFFSET	32
 
 
 ENTRY(kdb_kintr)
@@ -892,7 +894,9 @@ ENTRY(kdb_kintr)
 	cmpq	RET_OFFSET(%rax),%rdx	/* interrupt handler (2)? */
 	je	2f			/* if not: */
 	movq	(%rax),%rax		/* try next frame */
-	jmp	0b
+	testl	%rax,%rax
+	jnz	0b
+	ud2				/* oops, didn't find frame, fix me :/ */
 
 1:	movq	$kdb_from_iret,RET_OFFSET(%rax)
 	ret				/* returns to kernel/user stack */
-- 
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