Error handling configuration updates and Optimization for exception handling #7214

SenRamakri · 2018-06-13T21:15:21Z

Description

This change is targeted towards optimizing Error handling and exception handling to save memory.
The PR contains following changes:

Updates to configuration flags used in error handling implementation
Make Error history tracking switched off by default and enabled by using the config flag MBED_CONF_PLATFORM_ERROR_HIST_ENABLED.
Update exception handling code to remove dedicated fault safe printfs and to use mbed_error_printf.
Dedicated safe printfs were originally developed to print data over serial with minimal resources. But this adds more code space, so we are switching to use mbed_error_printf. Although it uses more resources, but it saves on rom usage.
Another change is to remove printing info on all threads always when generating exception report. This will be turned off by default and can be turned on using config flag MBED_CONF_PLATFORM_ERROR_ALL_THREADS_INFO if required.
These optimizations should save around 800 bytes on Rom.

Pull request type

[x] Fix
[ ] Refactor
[ ] New target
[ ] Feature
[ ] Breaking change

kjbracey · 2018-06-15T07:48:33Z

Looking at this, I'm a teeny bit nervous some of the prints are getting a bit close to the 128-byte buffer limit in mbed_error_vfprintf. I've seen people hit that problem in mbed_assert, which can certainly blow the limit and fail to print the full filename + line as a result. (Doubly bad in Greentea, which will actually show none of the assert due to no line terminator.)

So mbed_assert_internal does need its mbed_error_printf broken up - not sure if this does, but watch out for anywhere you're printing a filename in %s. That can be rather long.

0xc0170 · 2018-06-15T12:53:42Z

rtos/TARGET_CORTEX/TARGET_CORTEX_M/mbed_rtx_fault_handler.h

@@ -53,6 +53,6 @@ typedef struct {

 //This is a handler function called from Fault handler to print the error information out.
 //This runs in fault context and uses special functions(defined in mbed_rtx_fault_handler.c) to print the information without using C-lib support.
-__NO_RETURN void mbed_fault_handler (uint32_t fault_type, void *mbed_fault_context_in, void *osRtxInfoIn);
+void mbed_fault_handler (uint32_t fault_type, void *mbed_fault_context_in, void *osRtxInfoIn);


why are we removing no_return here?

@0xc0170 - With the new error handling implementation fault handler will call into error handler which will handle halting the system and thus no longer required here.

0xc0170 · 2018-06-15T12:55:59Z

platform/mbed_error.c

+    mbed_error_printf("\nLocation: 0x%X", ctx->error_address);
+
+#if MBED_CONF_PLATFORM_ERROR_FILENAME_CAPTURE_ENABLED && !defined(NDEBUG)
+    if((NULL != ctx->error_filename[0]) && (ctx->error_line_number != 0)) {


if ( space . Look at astyle failures for this changes in Travis

0xc0170 · 2018-06-15T12:57:04Z

rtos/TARGET_CORTEX/TARGET_CORTEX_M/mbed_rtx_fault_handler.c

 }

-void print_context_info(void)
+MBED_NOINLINE void print_context_info(void)


inlining was causing some problems for this function?

No specific problems with inlining. But sometimes debugging and also identifying the space required for individual functions becomes hard. So I removed inline as I was working on some optimizations.

0xc0170 · 2018-06-15T12:58:26Z

The PR contains following changes:

That info should be part of the commit messages here

SenRamakri · 2018-06-18T14:59:54Z

@0xc0170 - You mentioned my description should be part of commit messages? Are you meaning I should include the entire description?

SenRamakri · 2018-06-18T15:56:16Z

@kjbracey-arm - Good point about the mbed_error_printf/%s. Currently we are using %s for printing filename. I'll change the implementation to limit the filename length to 64 chars max, by default its 16. That should take care of this as we have one printf which prints the filename+linenum but nothing else.

SenRamakri · 2018-06-18T16:48:50Z

platform/mbed_error.h

+//We have to limit this to 64 bytes since we use mbed_error_printf for error reporting
+//and mbed_error_vfprintf uses 128bytes internal buffer which may not be sufficient for anything
+//longer that 64 bytes with the current implementation.
+#error "Unsupported error filename buffer length detected, max supported length is 64 chars. Please change MBED_CONF_PLATFORM_MAX_ERROR_FILENAME_LEN or max-error-filename-len in configuration."


@kjbracey-arm - Please see this change to limit the filename buffer to 64 chars. This should take care of 128 chars buffer limitation in mbed_error_printf implementation.

0xc0170 · 2018-06-19T10:49:09Z

@0xc0170 - You mentioned my description should be part of commit messages? Are you meaning I should include the entire description?

Yes, I dont see a reason why not.

This needs a rebase now

SenRamakri · 2018-06-20T02:46:36Z

@0xc0170 - Commit message has been updated.

0xc0170 · 2018-06-20T12:45:25Z

The last commit was amended. What I had in mind was reworked all 3 commits to provide details, this needs rebase interactive and edit each one of them . The last commit does not make much sense , or am I misreading the changes vs commit msg there (the last commit contains style changes that should be separate commit - this is making it hard to review).

The new configuration make Error history tracking switched off by default and enabled by using the config flag MBED_CONF_PLATFORM_ERROR_HIST_ENABLED. Config flag MBED_CONF_PLATFORM_ERROR_ALL_THREADS_INFO enables printing info of all threads. This will be turned off by default.

… and use mbed_error_printf to optimize memory usage. Dedicated safe printfs were originally developed to print data over serial with minimal resources. But this adds more code space, so we are switching to use mbed_error_printf.

…onfigs and astyle fixes.

SenRamakri · 2018-06-20T16:59:10Z

@0xc0170 - Commit messages have been split/re-worked.

cmonr

LGTM

cmonr · 2018-06-21T13:33:43Z

/morph build

mbed-ci · 2018-06-21T14:46:41Z

Build : FAILURE

Build number : 2418
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7214/

cmonr · 2018-06-21T14:59:14Z

Looks like the K64F example mbed-os-example-error-handling failed on all compilers, but looks like a simple fix.

SenRamakri · 2018-06-21T16:00:06Z

@cmonr - Thanks Cruz, I'll look into the failure and push a fix.

SenRamakri · 2018-06-24T14:06:14Z

@cmonr - I have pushed a fix to the example app(on master branch).

cmonr · 2018-06-25T00:24:53Z

/morph build

cmonr · 2018-06-25T00:26:54Z

@SenRamakri Thansk for the quick direct commit to the example, but I'm thinking that once an example becomes public, fixes and the such should come into the example as PRs instead of direct commits.

@ARMmbed/mbed-os-maintainers Thoughts? I'm not sure ownership/process is clear/public for internal examples that become public.

mbed-ci · 2018-06-25T01:14:55Z

Build : SUCCESS

Build number : 2437
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/7214/

Triggering tests

/morph test
/morph uvisor-test
/morph export-build
/morph mbed2-build

mbed-ci · 2018-06-25T02:43:10Z

Exporter Build : SUCCESS

Build number : 2069
Build artifacts/logs : http://mbed-os.s3-website-eu-west-1.amazonaws.com/?prefix=builds/exporter/7214/

mbed-ci · 2018-06-25T02:58:51Z

Test : SUCCESS

Build number : 2217
Test logs :http://mbed-os-logs.s3-website-us-west-1.amazonaws.com/?prefix=logs/7214/2217

SenRamakri requested review from cmonr, geky, 0xc0170 and studavekar June 13, 2018 21:15

0xc0170 added the needs: review label Jun 14, 2018

0xc0170 requested changes Jun 15, 2018

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SenRamakri force-pushed the sen_ErrorOptimAndConfig branch from b31e28e to 4a92075 Compare June 18, 2018 16:47

SenRamakri commented Jun 18, 2018

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SenRamakri force-pushed the sen_ErrorOptimAndConfig branch 2 times, most recently from 6057ccd to 28be10c Compare June 18, 2018 17:40

SenRamakri mentioned this pull request Jun 19, 2018

Updating Platform config page with latest configs ARMmbed/mbed-os-5-docs#600

Merged

SenRamakri force-pushed the sen_ErrorOptimAndConfig branch 2 times, most recently from 1736154 to dc66deb Compare June 19, 2018 17:46

SenRamakri added 3 commits June 20, 2018 11:56

Limit error filename capture to 64 chars, wrapping tests with right c…

baa44eb

…onfigs and astyle fixes.

SenRamakri force-pushed the sen_ErrorOptimAndConfig branch from dc66deb to baa44eb Compare June 20, 2018 16:57

0xc0170 requested a review from a team June 21, 2018 09:03

0xc0170 approved these changes Jun 21, 2018

View reviewed changes

cmonr approved these changes Jun 21, 2018

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cmonr added needs: CI release-version: 5.9.2 labels Jun 21, 2018

cmonr removed the needs: review label Jun 21, 2018

cmonr added needs: work and removed needs: CI labels Jun 21, 2018

cmonr added needs: CI and removed needs: work labels Jun 25, 2018

cmonr added ready for merge and removed needs: CI labels Jun 25, 2018

cmonr merged commit ea47342 into ARMmbed:master Jun 25, 2018

0xc0170 removed the ready for merge label Jun 25, 2018

SenRamakri mentioned this pull request Jul 2, 2018

Do not assume serial can be used for printing in faulthandler #7363

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Error handling configuration updates and Optimization for exception handling #7214

Error handling configuration updates and Optimization for exception handling #7214

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Error handling configuration updates and Optimization for exception handling #7214

Error handling configuration updates and Optimization for exception handling #7214

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