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sys_callN() wraps a bare ecall and calls no other function, so the compiler treats it as a leaf function: with frame pointers enabled, it only needs to spill the caller's s0, which it places in what up_backtrace()'s fp-chain walk assumes is ra's stack slot, while the real ra slot is never written. sched_backtrace() then misreads that slot as the return address for this frame, either resolving to a bogus symbol or, if the adjacent garbage happens to look out-of-range, terminating the backtrace early. Add "ra" to the ecall clobber list so the compiler spills/reloads ra around the ecall like a normal call site, keeping ra and the saved s0 in their expected slots. Gate this on CONFIG_FRAME_POINTER && CONFIG_SCHED_BACKTRACE, the only combination where up_backtrace()'s fp-chain walk is both valid (FRAME_POINTER) and actually exercised (SCHED_BACKTRACE); other configurations keep the original "memory"-only clobber and pay no extra cost. This only fixes the syscall boundary. Leaf functions that do not cross a syscall (e.g. up_idle()) can still lose their ra slot the same way and are not addressed here. Signed-off-by: liang.huang <liang.huang@houmo.ai> |
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| CMakeLists.txt | ||
| Kconfig | ||