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>
Link: https://lore.kernel.org/r/20230801111449.185301-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
}
#endif /* CONFIG_BPF_SYSCALL */
+static __always_inline int
+bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr)
+{
+ int ret = -EFAULT;
+
+ if (IS_ENABLED(CONFIG_BPF_EVENTS))
+ ret = copy_from_kernel_nofault(dst, unsafe_ptr, size);
+ if (unlikely(ret < 0))
+ memset(dst, 0, size);
+ return ret;
+}
+
void __bpf_free_used_btfs(struct bpf_prog_aux *aux,
struct btf_mod_pair *used_btfs, u32 len);
}
#ifndef CONFIG_BPF_JIT_ALWAYS_ON
-u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
-{
- memset(dst, 0, size);
- return -EFAULT;
-}
-
/**
* ___bpf_prog_run - run eBPF program on a given context
* @regs: is the array of MAX_BPF_EXT_REG eBPF pseudo-registers
DST = *(SIZE *)(unsigned long) (SRC + insn->off); \
CONT; \
LDX_PROBE_MEM_##SIZEOP: \
- bpf_probe_read_kernel(&DST, sizeof(SIZE), \
- (const void *)(long) (SRC + insn->off)); \
+ bpf_probe_read_kernel_common(&DST, sizeof(SIZE), \
+ (const void *)(long) (SRC + insn->off)); \
DST = *((SIZE *)&DST); \
CONT;
DST = *(SIZE *)(unsigned long) (SRC + insn->off); \
CONT; \
LDX_PROBE_MEMSX_##SIZEOP: \
- bpf_probe_read_kernel(&DST, sizeof(SIZE), \
+ bpf_probe_read_kernel_common(&DST, sizeof(SIZE), \
(const void *)(long) (SRC + insn->off)); \
DST = *((SIZE *)&DST); \
CONT;
.arg3_type = ARG_ANYTHING,
};
-static __always_inline int
-bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr)
-{
- int ret;
-
- ret = copy_from_kernel_nofault(dst, unsafe_ptr, size);
- if (unlikely(ret < 0))
- memset(dst, 0, size);
- return ret;
-}
-
BPF_CALL_3(bpf_probe_read_kernel, void *, dst, u32, size,
const void *, unsafe_ptr)
{