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a37c20b417
* Patched longjmp to be context-switch safe longjmp modifies the windowbase and windowstart registers, which isn't safe if a context switch occurs during the modification. After a context switch, windowstart and windowbase will be different, leading to a wrongly set windowstart bit due to longjmp writing it based on the windowbase before the context switch. This corrupts the registers at the next window overflow reaching that wrongly set bit. The solution is to disable interrupts during this code. It is only 6 instructions long, the impact shouldn't be significant. The fix is implemented as a wrapper which replaces the original first instructions of longjmp which are buggy. Then, it jumps back to execute the rest of the original longjmp function. Added a comparably reliable test to the test apps.
72 lines
2.7 KiB
ArmAsm
72 lines
2.7 KiB
ArmAsm
/*
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Copyright (c) 2001-2006 by Tensilica Inc.
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Permission is hereby granted, free of charge, to any person obtaining
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a copy of this software and associated documentation files (the
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"Software"), to deal in the Software without restriction, including
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without limitation the rights to use, copy, modify, merge, publish,
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distribute, sublicense, and/or sell copies of the Software, and to
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permit persons to whom the Software is furnished to do so, subject to
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the following conditions:
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The above copyright notice and this permission notice shall be included
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in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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This file contains a modified version of the original Xtensa longjmp implementation.
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In this modified version, setting WINDOWSTART = 1 << WINDOWBASE is done inside a critical section.
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This is necessary because after a FreeRTOS context switch in IDF, the values of WINDOWBASE and WINDOWSTART
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are not guaranteed to be the same as before the context switch.
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*/
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#include <xtensa/corebits.h>
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/*
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Replacement of the first instructions of void longjmp (jmp_buf env, int val)
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*/
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.align 4
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.literal_position
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.global __wrap_longjmp
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.type __wrap_longjmp, @function
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__wrap_longjmp:
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entry sp, 16
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/* Deactivate interrupts in order to modify WINDOWBASE and WINDOWSTART. */
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rsr a7, PS /* to be restored after SPILL_ALL_WINDOWS */
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movi a5, PS_EXCM /* PS_INTLEVEL_MASK */
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or a5, a7, a5 /* get the current INTLEVEL */
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wsr a5, PS
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/* Invalidate all but the current window;
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set WindowStart to (1 << WindowBase). */
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rsr a5, WINDOWBASE
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movi a4, 1
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ssl a5
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sll a4, a4
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wsr a4, WINDOWSTART
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rsync
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/* Activate interrupts again after modifying WINDOWBASE and WINDOWSTART. */
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wsr a7, PS
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/* Jump back to original longjmp implementation.
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The jump target is the instrucion
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l32i a0, a2, 64
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of the original code. Hence, the original code's entry instruction and windowstart modification are left
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out.
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*/
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movi a0, __real_longjmp + 20
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jx a0
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.size __wrap_longjmp, . - __wrap_longjmp
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