soc/amd/picasso/bootblock: Write EIP to secure S3
This change is required so we have a defined entry point on S3. Without
this, the S3_RESUME_EIP_MSR register could in theory be written to
later which would be a security risk.
BUG=b:147042464
TEST=Resume trembyle and see bootblock start.
coreboot-4.12-512-g65779ebcf73f-dirty Thu Jun 4 22:38:17 UTC 2020 smm starting (log level: 8)...
SMI# #6
SMI#: SLP = 0x0c01
Chrome EC: Set SMI mask to 0x0000000000000000
Chrome EC: Set SCI mask to 0x0000000000000000
Clearing pending EC events. Error code EC_RES_UNAVAILABLE(9) is expected.
EC returned error result code 9
SMI#: Entering S3 (Suspend-To-RAM)
PSP: Prepare to enter sleep state 3... OK
SMU: Put system into S3/S4/S5
Timestamp - start of bootblock: 18446744070740509170
coreboot-4.12-512-g65779ebcf73f-dirty Thu Jun 4 22:38:17 UTC 2020 bootblock starting (log level: 8)...
Family_Model: 00810f81
PMxC0 STATUS: 0x200800 SleepReset BIT11
I2C bus 3 version 0x3132322a
DW I2C bus 3 at 0xfedc5000 (400 KHz)
Timestamp - end of bootblock: 18446744070804450274
VBOOT: Loading verstage.
FMAP: area COREBOOT found @ c75000 (3715072 bytes)
CBFS: Locating 'fallback/verstage'
CBFS: Found @ offset 61b80 size cee4
PROG_RUN: Setting MTRR to cache stage. base: 0x04000000, size: 0x00010000
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I4b0b0d0d576fc42b1628a4547a5c9a10bcbe9d37
Reviewed-on: https://review.coreboot.org/c/coreboot/+/42088
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
diff --git a/src/soc/amd/picasso/bootblock/bootblock.c b/src/soc/amd/picasso/bootblock/bootblock.c
index 606440b..a3935cc 100644
--- a/src/soc/amd/picasso/bootblock/bootblock.c
+++ b/src/soc/amd/picasso/bootblock/bootblock.c
@@ -12,6 +12,9 @@
#include <soc/southbridge.h>
#include <soc/i2c.h>
#include <amdblocks/amd_pci_mmconf.h>
+#include <acpi/acpi.h>
+
+asmlinkage void bootblock_resume_entry(void);
/* PSP performs the memory training and setting up DRAM map prior to x86 cores
being released. Honor TOP_MEM and set up caching from 0 til TOP_MEM. Likewise,
@@ -84,9 +87,27 @@
enable_cache();
}
+static void write_resume_eip(void)
+{
+ msr_t s3_resume_entry = {
+ .hi = (uint64_t)(uintptr_t)bootblock_resume_entry >> 32,
+ .lo = (uintptr_t)bootblock_resume_entry & 0xffffffff,
+ };
+
+ /*
+ * Writing to the EIP register can only be done once, otherwise a fault is triggered.
+ * When this register is written, it will trigger the microcode to stash the CPU state
+ * (crX , mtrrs, registers, etc) into the CC6 save area. On resume, the state will be
+ * restored and execution will continue at the EIP.
+ */
+ if (!acpi_is_wakeup_s3())
+ wrmsr(S3_RESUME_EIP_MSR, s3_resume_entry);
+}
+
asmlinkage void bootblock_c_entry(uint64_t base_timestamp)
{
set_caching();
+ write_resume_eip();
enable_pci_mmconf();
bootblock_main_with_basetime(base_timestamp);
diff --git a/src/soc/amd/picasso/bootblock/pre_c.S b/src/soc/amd/picasso/bootblock/pre_c.S
index 5c186f1..83e5491 100644
--- a/src/soc/amd/picasso/bootblock/pre_c.S
+++ b/src/soc/amd/picasso/bootblock/pre_c.S
@@ -2,6 +2,17 @@
#include <cpu/x86/post_code.h>
+.global bootblock_resume_entry
+bootblock_resume_entry:
+ post_code(0xb0)
+
+ /* Get an early timestamp */
+ rdtsc
+ movd %eax, %mm1
+ movd %edx, %mm2
+
+ /* Fall through to bootblock_pre_c_entry */
+
/*
* on entry:
* mm0: BIST (ignored)