# HG changeset patch
# User Alex Olson <alex.ol...@starlab.io>
# Date 1657558891 18000
# Mon Jul 11 12:01:31 2022 -0500
# Node ID 0552b7ac10e28b378dd139e5ca3838039c472827
# Parent fa60b63892e8f9d4278950b44ed136d2b12d19cc
Correct IDT exception handler addresses
The exception handlers configured in the IDT weren't properly executed
during exceptions as _start/TBOOT_START are not 64K aligned (0x804000).
This revision corrects the arithmetic so that the "int_handler" routine
gets properly executed instead of "int_handler - 0x4000".
NOTE: A simple way to test this is to insert 'asm volatile("ud2");' in
begin_launch().
Signed-off-by: Alex Olson <alex.ol...@starlab.io>
diff -r fa60b63892e8 -r 0552b7ac10e2 tboot/common/boot.S
--- a/tboot/common/boot.S Fri Jun 17 11:39:11 2022 +0300
+++ b/tboot/common/boot.S Mon Jul 11 12:01:31 2022 -0500
@@ -400,23 +400,28 @@
.align 8
+/* Below assumes "_start" is exactly at TBOOT_START and is needed to allow
arithmetic: */
+#define INT_HANDLER_ADDR (int_handler - _start + TBOOT_START)
+#define INT_HANDLER_LO16 (INT_HANDLER_ADDR & 0xffff)
+#define INT_HANDLER_HI16 (INT_HANDLER_ADDR >> 16)
+
idt_table:
.rept 18
- .word int_handler - _start
+ .word INT_HANDLER_LO16
.word cs_sel
.word 0x8e00 /* present, DPL=0, 32b, interrupt */
- .word (int_handler - _start + TBOOT_START) >> 16
+ .word INT_HANDLER_HI16
.endr
/* for machine-check exception */
- .word int_handler - _start
+ .word INT_HANDLER_LO16
.word cs_sel
.word 0x8f00 /* present, DPL=0, 32b, trap */
- .word (int_handler - _start + TBOOT_START) >> 16
+ .word INT_HANDLER_HI16
.rept 237
- .word int_handler - _start
+ .word INT_HANDLER_LO16
.word cs_sel
.word 0x8e00 /* present, DPL=0, 32b, interrupt */
- .word (int_handler - _start + TBOOT_START) >> 16
+ .word INT_HANDLER_HI16
.endr
idt_table_end:
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