Merge pull request #2974 from tannewt/esp32s2_spill

Spill registers before scanning the stack.
This commit is contained in:
Dan Halbert 2020-05-28 22:10:46 -04:00 committed by GitHub
commit 7ea95457ee
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2 changed files with 42 additions and 1 deletions

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@ -37,6 +37,24 @@ void mp_hal_delay_us(mp_uint_t delay) {
mp_hal_delay_ms(delay / 1000);
}
mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs) {
// This is provided by the esp-idf/components/xtensa/esp32s2/libhal.a binary
// blob.
extern void xthal_window_spill(void);
mp_uint_t cpu_get_regs_and_sp(mp_uint_t *regs, uint8_t reg_count) {
// xtensa has more registers than an instruction can address. The 16 that
// can be addressed are called the "window". When a function is called or
// returns the window rotates. This allows for more efficient function calls
// because ram doesn't need to be used. It's only used if the window wraps
// around onto itself. At that point values are "spilled" to empty spots in
// the stack that were set aside. When the window rotates back around (on
// function return), the values are restored into the register from ram.
// So, in order to read the values in the stack scan we must make sure all
// of the register values we care about have been spilled to RAM. Luckily,
// there is a HAL call to do it. There is a bit of a race condition here
// because the register value could change after it's been restored but that
// is unlikely to happen with a heap pointer while we do a GC.
xthal_window_spill();
return (mp_uint_t) __builtin_frame_address(0);
}

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@ -0,0 +1,23 @@
"""Simple script that translates "Backtrace:" lines from the ESP output to files
and line numbers.
Run with: python3 tools/decode_backtrace.py <board>
Enter the backtrace line at the "? " prompt. CTRL-C to exit the script.
"""
import subprocess
import sys
board = sys.argv[1]
print(board)
while True:
addresses = input("? ")
if addresses.startswith("Backtrace:"):
addresses = addresses[len("Backtrace:"):]
addresses = addresses.strip().split()
addresses = [address.split(":")[0] for address in addresses]
print('got', addresses)
subprocess.run(["xtensa-esp32s2-elf-addr2line",
"-e", "build-{}/firmware.elf".format(board)] + addresses)