Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/42088 )
Change subject: soc/amd/picasso/bootblock: Write EIP to secure S3 ......................................................................
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 --- M src/include/cpu/amd/msr.h M src/soc/amd/picasso/bootblock/bootblock.c M src/soc/amd/picasso/bootblock/pre_c.S 3 files changed, 33 insertions(+), 0 deletions(-)
Approvals: build bot (Jenkins): Verified Aaron Durbin: Looks good to me, approved Marshall Dawson: Looks good to me, approved
diff --git a/src/include/cpu/amd/msr.h b/src/include/cpu/amd/msr.h index 606ea23..e466e7b 100644 --- a/src/include/cpu/amd/msr.h +++ b/src/include/cpu/amd/msr.h @@ -72,6 +72,7 @@ #define EX_CFG_MSR 0xC001102C #define LS_CFG2_MSR 0xC001102D #define IBS_OP_DATA3_MSR 0xC0011037 +#define S3_RESUME_EIP_MSR 0xC00110E0
#define MSR_PATCH_LEVEL 0x0000008B #define CORE_PERF_BOOST_CTRL 0x15c 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)