Commit 2d369b4b authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Daniel Borkmann
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libbpf: Extend BPF_KSYSCALL documentation 



Explicitly list known quirks. Mention that socket-related syscalls can be
invoked via socketcall().

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/bpf/20220726134008.256968-2-iii@linux.ibm.com
parent bd82ea52

tools/lib/bpf/bpf_tracing.h

+11 −4
Original line number Diff line number Diff line
@@ -523,10 +523,17 @@ static __always_inline typeof(name(0)) ____##name(struct pt_regs *ctx, ##args) 
 * Original struct pt_regs * context is preserved as 'ctx' argument. This might

 * be necessary when using BPF helpers like bpf_perf_event_output().

 *

 * At the moment BPF_KSYSCALL does not handle all the calling convention

 * quirks for mmap(), clone() and compat syscalls transparrently. This may or

 * may not change in the future. User needs to take extra measures to handle

 * such quirks explicitly, if necessary.

 * At the moment BPF_KSYSCALL does not transparently handle all the calling

 * convention quirks for the following syscalls:

 *

 * - mmap(): __ARCH_WANT_SYS_OLD_MMAP.

 * - clone(): CONFIG_CLONE_BACKWARDS, CONFIG_CLONE_BACKWARDS2 and

 *            CONFIG_CLONE_BACKWARDS3.

 * - socket-related syscalls: __ARCH_WANT_SYS_SOCKETCALL.

 * - compat syscalls.

 *

 * This may or may not change in the future. User needs to take extra measures

 * to handle such quirks explicitly, if necessary.

 *

 * This macro relies on BPF CO-RE support and virtual __kconfig externs.

 */