[rom_ext] Lock the correct ROM_EXT region #25892
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cfrantz
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moidx
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jettr
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| uint32_t region_start = config->start; | ||
| uint32_t region_end = region_start + config->size; | ||
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| // When applying the flash configuration, a region is a ROM_EXT region if |
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Thank you for the detailed comment! The comment and the logic don't quite match either other. I agree with the comment. The logic to match the comment would be
kRomExtAStart <= region_start < kRomExtAEnd &&
kRomExtAStart < region_end <= kRomExtAEnd
(and maybe we need an explicit region_start<=region_end check too?)
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🤦 How embarrassing. A total logic fail.
I've fixed this and added unit tests to owner_block_unittest.cc to test the overlap/exclusivity checking functions.
We don't need to test region_start <= region_end because the bounds are computed from a start and size (which are uint16_t) and the region_* values are uint32_t.
I added a sanity check to the end value: if the end is beyond the total size of the flash, the configuration is invalid.
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Ownership flash lockdown was protecting and locking all regions in the same slot that booted the owner code. However, the ROM_EXT and owner code don't have to boot from the same side of the flash. 1. Protect the ROM_EXT and owner regions each according to their boot slot. 2. Test each combination of ROM_EXT slot and owner slot in the `flash_permission_test`. Fixes lowRISC#25435. Signed-off-by: Chris Frantz <[email protected]>
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jettr
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Ownership flash lockdown was protecting and locking all regions in the same slot that booted the owner code. However, the ROM_EXT and owner code don't have to boot from the same side of the flash.
flash_permission_test.Fixes #25435.