[S] Change in coreboot[master]: acpi/acpi.c: Fix einj generation pointer arithmetics

[Jonathan Zhang (Code Review)]

Attention is currently required from: Arthur Heymans.

Hello Arthur Heymans,

I'd like you to do a code review.
Please visit

https://review.coreboot.org/c/coreboot/+/69326

to review the following change.

Change subject: acpi/acpi.c: Fix einj generation pointer arithmetics
......................................................................

acpi/acpi.c: Fix einj generation pointer arithmetics

Without a cast the aritmetics of

tat = einj + sizeof(acpi_einj_smi_t)

is the same as

tat = (uintptr_t)einj + size(acpi_einj_smi_t) * size(acpi_einj_smi_t)

So it overshoots the intended offset by a lot.

This issue only came apparent because now einj is in the small IMD region
which is close to TSEG. With the wrong aritmetics the tat pointer ended
up inside TSEG which is not accessible from the OS causing exceptions.

TEST: observe that tat pointer is inside the small IBM below
TSEG (0x78000000 on our setup).
"acpi_create_einj trigger_action_table = 0x77ffe89c"

Change-Id: I3ab64b95c33eef01b2048816a21e17855bcb2f54
Signed-off-by: Arthur Heymans 
Signed-off-by: Jonathan Zhang 
---
M src/acpi/acpi.c
1 file changed, 31 insertions(+), 1 deletion(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/26/69326/1

diff --git a/src/acpi/acpi.c b/src/acpi/acpi.c
index e211558..4d0c59d 100644
--- a/src/acpi/acpi.c
+++ b/src/acpi/acpi.c
@@ -26,6 +26,7 @@
 #include <device/mmio.h>
 #include <device/pci.h>
 #include <pc80/mc146818rtc.h>
+#include <stdint.h>
 #include <string.h>
 #include <types.h>
 #include <version.h>
@@ -868,7 +869,7 @@

printk(BIOS_DEBUG, "%s einj_smi = %p\n", __func__, einj_smi);
    memset(einj_smi, 0, sizeof(acpi_einj_smi_t));
-	tat = (acpi_einj_trigger_table_t *)(einj_smi + sizeof(acpi_einj_smi_t));
+	tat = (acpi_einj_trigger_table_t *)((uint8_t *)einj_smi + sizeof(acpi_einj_smi_t));
    tat->header_size =  16;
    tat->revision =  0;
    tat->table_size =  sizeof(acpi_einj_trigger_table_t) +