Messages in this thread | | | Date | Tue, 1 Aug 2023 07:41:26 -0700 | Subject | Re: [PATCH] [v5] bpf: fix bpf_probe_read_kernel prototype mismatch | From | Yonghong Song <> |
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On 8/1/23 4:13 AM, Arnd Bergmann wrote: > From: Arnd Bergmann <arnd@arndb.de> > > bpf_probe_read_kernel() has a __weak definition in core.c and another > definition with an incompatible prototype in kernel/trace/bpf_trace.c, > when CONFIG_BPF_EVENTS is enabled. > > Since the two are incompatible, there cannot be a shared declaration in > a header file, but the lack of a prototype causes a W=1 warning: > > kernel/bpf/core.c:1638:12: error: no previous prototype for 'bpf_probe_read_kernel' [-Werror=missing-prototypes] > > On 32-bit architectures, the local prototype > > u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) > > passes arguments in other registers as the one in bpf_trace.c > > BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size, > const void *, unsafe_ptr) > > which uses 64-bit arguments in pairs of registers. > > As both versions of the function are fairly simple and only really > differ in one line, just move them into a header file as an inline > function that does not add any overhead for the bpf_trace.c callers > and actually avoids a function call for the other one. > > Cc: stable@vger.kernel.org > Link: https://lore.kernel.org/all/ac25cb0f-b804-1649-3afb-1dc6138c2716@iogearbox.net/ > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
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