arch/rv32i: Reduce PMP stack usage #2020
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This is the first step to reducing the stack usage from the PMP config structs.
Before this patch the stack usage was:
720 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
After this patch it is now:
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
The configure_mpu() function is still the second highest user of the
stack (after reset_handler()) but this is an improvement.
This is a step to help fix: tock#2016
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
2 tasks
2 tasks
hudson-ayers
approved these changes
Jul 15, 2020
bradjc
approved these changes
Jul 15, 2020
bradjc
added
risc-v
alistair23
added a commit
to alistair23/tock
that referenced
this pull request
Jul 17, 2020
Previously we would sort the PMP regions everytime we configured the
MPU. This was wasteful in terms of instructions but also wasted stack
space, probably because we cloned the PMPConfig regions.
This patch changes the sorting to only happen after a change is made to
the regions. This should save the number of times we have to sort,
remove sorting out of the critical path and saves a lot of stack space.
See below for the stack changes:
### Release build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
0 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
16 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
### Debug build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
NOTE: All above numbers already include: tock#2020
I haven't compared instruction diffs, but I'm assuming we reduce the
number of instructions run on app swap as well.
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
|
bors r+ |
bors bot
added a commit
that referenced
this pull request
Jul 20, 2020
2021: arch/rv32i: Don't sort PMP regions when we configure the MPU r=ppannuto a=alistair23
### Pull Request Overview
Previously we would sort the PMP regions everytime we configured the
MPU. This was wasteful in terms of instructions but also wasted stack
space, probably because we cloned the PMPConfig regions.
This patch changes the sorting to only happen after a change is made to
the regions. This should save the number of times we have to sort,
remove sorting out of the critical path and saves a lot of stack space.
See below for the stack changes:
### Release build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
0 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
16 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
### Debug build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
NOTE: All above numbers already include: #2020
I haven't compared instruction diffs, but I'm assuming we reduce the
number of instructions run on app swap as well.
### Testing Strategy
Tested running apps on QEMU OpenTitan.
### TODO or Help Wanted
### Documentation Updated
- [X] Updated the relevant files in `/docs`, or no updates are required.
### Formatting
- [X] Ran `make prepush`.
Co-authored-by: Alistair Francis <alistair.francis@wdc.com>
hudson-ayers
pushed a commit
that referenced
this pull request
Mar 7, 2022
Previously we would sort the PMP regions everytime we configured the
MPU. This was wasteful in terms of instructions but also wasted stack
space, probably because we cloned the PMPConfig regions.
This patch changes the sorting to only happen after a change is made to
the regions. This should save the number of times we have to sort,
remove sorting out of the critical path and saves a lot of stack space.
See below for the stack changes:
### Release build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
0 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17hb3b05a589563feedE
16 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17hd6078caa7928d4d8E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h5967285bd6ec5881E
### Debug build ###
## Before this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
592 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
## After this patch ##
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$15allocate_region17h272c094b5b64d63bE
96 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$26allocate_app_memory_region17h56b3decc4c649f8cE
32 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$24update_app_memory_region17h55a48db93ba6d713E
80 _ZN68_$LT$rv32i..pmp..PMPConfig$u20$as$u20$kernel..platform..mpu..MPU$GT$13configure_mpu17h32d25c65ffe73910E
NOTE: All above numbers already include: #2020
I haven't compared instruction diffs, but I'm assuming we reduce the
number of instructions run on app swap as well.
BUG=none
TEST=make
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
(cherry picked from commit bed1b92)
Change-Id: I78a1a37d6d693e8399ba28f7610682ce2e9d0b26
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Pull Request Overview
This is the first step to reducing the stack usage from the PMP config structs.
Before this patch the stack usage was:
After this patch it is now:
The configure_mpu() function is still the second highest user of the
stack (after reset_handler()) but this is an improvement.
This is a step to help fix: #2016
Testing Strategy
None.
TODO or Help Wanted
Documentation Updated
/docs, or no updates are required.Formatting
make prepush.