TBF: Add "Fixed Addresses" TLV #1845
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Unsafe not needed for parsing, make it more official and clear.
If the process included fixed addresses in its header, make sure those are used, otherwise return an error. Note, this does not yet actually try to use the correct address (i.e. in ram) that the kernel could try to optimize for.
Allows processes to communicate to the kernel they need a very specific address.
bradjc
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kernel
P-Significant
jrvanwhy
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May 12, 2020
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Updated. |
ppannuto
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May 13, 2020
jrvanwhy
previously approved these changes
May 13, 2020
Co-authored-by: Pat Pannuto <pat.pannuto@gmail.com>
ppannuto
previously approved these changes
May 13, 2020
jrvanwhy
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May 13, 2020
ppannuto
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May 13, 2020
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alistair23
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May 14, 2020
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Any other comments @tock/core-wg? |
hudson-ayers
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May 18, 2020
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208: linker: add sram origin symbol r=bradjc a=bradjc This allows elf2tab to determine what the start of RAM address is when generating a fixed address header in the TBF. See tock/elf2tab#23 and tock/tock#1845. Co-authored-by: Brad Campbell <bradjc5@gmail.com>
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Pull Request Overview
Part of: #1283 and #1465
This adds a new TLV header (
FixedAddresses) for processes to specify the addresses in flash and ram they need (if they require fixed addresses, i.e. are not position independent. The kernel then checks these addresses when creating processes, and throws errors if they are not met. Note: this does not change the kernel to try to give a process its requested memory address.The main benefit of this is that non-PIC apps can use this header and the kernel can catch errors when loading processes. Right now misalignments cause other errors to pop up once a process is running, and these are difficult to debug.
I have related changes to elf2tab and tockloader in progress, but will wait to PR those until any changes are ironed out here.
Testing Strategy
Adding the headers to Hail and verifying that apps work when they match and an error is displayed when they do not.
TODO or Help Wanted
Documentation Updated
/docs, or no updates are required.Formatting
make formatall.