Jordan Rome 131afd9a57 bpf: Add crosstask check to __bpf_get_stack ... [ Upstream commit b8e3a87a62 ] Currently get_perf_callchain only supports user stack walking for the current task. Passing the correct *crosstask* param will return 0 frames if the task passed to __bpf_get_stack isn't the current one instead of a single incorrect frame/address. This change passes the correct *crosstask* param but also does a preemptive check in __bpf_get_stack if the task is current and returns -EOPNOTSUPP if it is not. This issue was found using bpf_get_task_stack inside a BPF iterator ("iter/task"), which iterates over all tasks. bpf_get_task_stack works fine for fetching kernel stacks but because get_perf_callchain relies on the caller to know if the requested *task* is the current one (via *crosstask*) it was failing in a confusing way. It might be possible to get user stacks for all tasks utilizing something like access_process_vm but that requires the bpf program calling bpf_get_task_stack to be sleepable and would therefore be a breaking change. Fixes: fa28dcb82a ("bpf: Introduce helper bpf_get_task_stack()") Signed-off-by: Jordan Rome <jordalgo@meta.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20231108112334.3433136-1-jordalgo@meta.com Signed-off-by: Sasha Levin <sashal@kernel.org>		2024-01-25 14:52:36 -08:00
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asm
asm-generic	x86/insn: Use get_unaligned() instead of memcpy()	2021-11-18 19:16:30 +01:00
linux	bpf: Fix BTF_ID symbol generation collision in tools/	2023-10-06 13:18:23 +02:00
nolibc	tools/nolibc: fix the O_* fcntl/open macro definitions for riscv	2023-01-18 11:48:56 +01:00
tools	tools include: add dis-asm-compat.h to handle version differences	2023-03-17 08:49:04 +01:00
trace/events
uapi	bpf: Add crosstask check to __bpf_get_stack	2024-01-25 14:52:36 -08:00
vdso