[pentest] Make iCache/dummy instr. enable/disable configurable #26535
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nasahlpa
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| cpuctrl_csr = bitfield_field32_write( | ||
| cpuctrl_csr, (bitfield_field32_t){.mask = 0x1, .index = 0}, 0); | ||
| if (disable_icache) { | ||
| cpuctrl_csr = bitfield_field32_write( | ||
| cpuctrl_csr, (bitfield_field32_t){.mask = 0x1, .index = 0}, 0); | ||
| } | ||
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| // Disable dummy instructions. | ||
| cpuctrl_csr = bitfield_field32_write( | ||
| cpuctrl_csr, (bitfield_field32_t){.mask = 0x1, .index = 2}, 0); | ||
| if (disable_dummy_instr) { | ||
| cpuctrl_csr = bitfield_field32_write( | ||
| cpuctrl_csr, (bitfield_field32_t){.mask = 0x1, .index = 2}, 0); | ||
| } | ||
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The reset value for this register is all 0: https://ibex-core.readthedocs.io/en/latest/03_reference/cs_registers.html#cpu-control-and-status-register-cpuctrlsts
I guess there is maybe some ROM code to enable the iCache and Dummy instructions. Or should we actually change the function here to enable it if the disable is not set? I would like to avoid that we don't set the disable (and think the cache is enabled) while it's actually disabled.
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You are totally right, this is a bit misleading. Yes, the iCache and dummy instructions are configured in the ROM.
In our case, the security evaluator is interested in the following:
- Test the chip without iCache and/or dummy instructions
- Test the chip with the configuration set in the ROM
So the evaluator does not necessarily know the default configuration. Hence, I'd leave it as it is (you only can disable it or keep the default config) and update the description of the function.
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This is reasonable. Thanks for explaining!
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Previously, in all pentests, the icache as well as the dummy instructions were disabled to achieve constant timing between test runs. However, for certain tests, we want to test the default iCache and dummy instruction configuration that has been set in the ROM. Signed-off-by: Pascal Nasahl <[email protected]>
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Previously, in all pentests, the icache as well as the dummy instructions were disabled to achieve constant timing between test runs. However, for certain tests, we want to test with iCache or with dummy instructions enabled. Make this configurable in the init function of the tests.