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| author | Nicolas Boichat <drinkcat@chromium.org> | 2018-07-19 15:52:10 +0800 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2018-08-15 08:46:51 -0700 |
| commit | af9c4a5ec91d233fc8d2b2eef7639d811664b086 (patch) | |
| tree | 94cf24c7da55093d63c2f8ac9d45b39e99494b3f /core | |
| parent | b48acb749c179bd682c28583ff326829ed925e9a (diff) | |
| download | chrome-ec-af9c4a5ec91d233fc8d2b2eef7639d811664b086.tar.gz | |
rollback: Prevent rollback region readback using MPU
We want to prevent easy readout of the rollback region, so we
protect it using the MPU. There is a short duration of time where
the region is unprotected (when we actually need to read the
information back), but we shorten it by disabling interrupts.
BRANCH=none
BUG=b:111330723
TEST=flashread 0xe0000, rw 0x80e0020, md 0x80e0020,
ectool flashread 0xc0000 0x1000 x
=> All cause EC to crash and reboot
TEST=rollbackinfo still works
Change-Id: I85ee757b3e261de392af03bd958b36d140a1080a
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1143106
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Nicolas Norvez <norvez@chromium.org>
Diffstat (limited to 'core')
| -rw-r--r-- | core/cortex-m/include/mpu.h | 7 | ||||
| -rw-r--r-- | core/cortex-m/mpu.c | 14 |
2 files changed, 21 insertions, 0 deletions
diff --git a/core/cortex-m/include/mpu.h b/core/cortex-m/include/mpu.h index 049f32f4f3..2dcf8be660 100644 --- a/core/cortex-m/include/mpu.h +++ b/core/cortex-m/include/mpu.h @@ -31,6 +31,8 @@ enum mpu_region { REGION_CHIP_RESERVED = 7, /* Reserved for use in chip/ */ /* only for chips with MPU supporting 16 regions */ REGION_UNCACHED_RAM = 8, /* For uncached data RAM */ + REGION_UNCACHED_RAM2 = 9, /* Second region for unaligned size */ + REGION_ROLLBACK = 10, /* For rollback */ }; #define MPU_TYPE REG32(0xe000ed90) @@ -104,6 +106,11 @@ int mpu_lock_ro_flash(void); int mpu_lock_rw_flash(void); /** + * Protect/unprotect rollback region readback. + */ +int mpu_lock_rollback(int lock); + +/** * Initialize MPU. * It disables all regions if MPU is implemented. Otherwise, returns * EC_ERROR_UNIMPLEMENTED. diff --git a/core/cortex-m/mpu.c b/core/cortex-m/mpu.c index d99540287c..795f809eca 100644 --- a/core/cortex-m/mpu.c +++ b/core/cortex-m/mpu.c @@ -211,6 +211,16 @@ int mpu_lock_rw_flash(void) } #endif /* !CONFIG_EXTERNAL_STORAGE */ +#ifdef CONFIG_ROLLBACK_MPU_PROTECT +int mpu_lock_rollback(int lock) +{ + return mpu_config_region(REGION_ROLLBACK, + CONFIG_MAPPED_STORAGE_BASE + CONFIG_ROLLBACK_OFF, + CONFIG_ROLLBACK_SIZE, MPU_ATTR_XN | MPU_ATTR_NO_NO, + lock); +} +#endif + #ifdef CONFIG_CHIP_UNCACHED_REGION /* Store temporarily the regions ranges to use them for the MPU configuration */ #define REGION(_name, _flag, _start, _size) \ @@ -237,6 +247,10 @@ int mpu_pre_init(void) for (i = 0; i < MPU_TYPE_REG_COUNT(mpu_type); ++i) mpu_config_region(i, CONFIG_RAM_BASE, CONFIG_RAM_SIZE, 0, 0); +#ifdef CONFIG_ROLLBACK_MPU_PROTECT + mpu_lock_rollback(1); +#endif + #ifdef CONFIG_ARMV7M_CACHE #ifdef CONFIG_CHIP_UNCACHED_REGION mpu_config_region(REGION_UNCACHED_RAM, |