Jordan Rome a341738951 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 15:35:19 -08:00
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asm	tools headers: Update the copy of x86's mem{cpy,set}_64.S used in 'perf bench'	2023-05-17 10:42:19 -03:00
asm-generic	tools: KVM: selftests: Convert clear/set_bit() to actual atomics	2022-12-02 13:22:35 -05:00
linux	maple_tree: add GFP_KERNEL to allocations in mas_expected_entries()	2023-10-18 12:12:41 -07:00
nolibc	tools/nolibc: mark start_c as weak	2023-10-12 21:13:51 +02:00
tools	tools include: add dis-asm-compat.h to handle version differences	2022-08-01 15:29:49 -03:00
trace/events
uapi	bpf: Add crosstask check to __bpf_get_stack	2024-01-25 15:35:19 -08:00
vdso	tools headers: Synchronize {linux,vdso}/bits.h with the kernel sources	2023-03-03 22:34:15 -03:00