[XS] Change in coreboot[main]: cpu/x86/smm: Add support for exception handling

[Patrick Rudolph (Code Review)]

Patrick Rudolph has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/87208?usp=email )

Change subject: cpu/x86/smm: Add support for exception handling
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cpu/x86/smm: Add support for exception handling

Add an expception handler to SMM to debug crashes when a serial
console it enabled and DEBUG_SMI is set. Allows to narrow down
issues faster than letting the machine tripple faulting.

Change-Id: I2ccaf8d23d508d773ce56912983884ad6832ede6
Signed-off-by: Patrick Rudolph 
---
M src/arch/x86/exception.c
M src/cpu/x86/smm/smm_module_handler.c
2 files changed, 6 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/08/87208/1

diff --git a/src/arch/x86/exception.c b/src/arch/x86/exception.c
index 224f0e1..e21cfa6 100644
--- a/src/arch/x86/exception.c
+++ b/src/arch/x86/exception.c
@@ -665,6 +665,8 @@

load_idt(idt, sizeof(idt));

+#if !ENV_SMM
    null_breakpoint_init();
    stack_canary_breakpoint_init();
+#endif
 }
diff --git a/src/cpu/x86/smm/smm_module_handler.c b/src/cpu/x86/smm/smm_module_handler.c
index d25b5f4..d9f6420 100644
--- a/src/cpu/x86/smm/smm_module_handler.c
+++ b/src/cpu/x86/smm/smm_module_handler.c
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */

#include <arch/io.h>
+#include <arch/exception.h>
 #include <commonlib/region.h>
 #include <console/cbmem_console.h>
 #include <console/console.h>
@@ -169,6 +170,9 @@

printk(BIOS_SPEW, "\nSMI# #%d\n", cpu);

+	if (CONFIG(DEBUG_SMI) && CONFIG(CONSOLE_SERIAL))
+		exception_init();
+
    /* Allow drivers to initialize variables in SMM context. */
    if (do_driver_init) {
 #if CONFIG(SPI_FLASH_SMM)