| Message ID | 20230602135128.1498362-2-arnd@kernel.org (mailing list archive) |
|---|---|
| State | Handled Elsewhere |
| Headers | show |
| Series | None | expand |
On 6/2/23 6:50 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. > > Change the core.c file to only reference the inner > bpf_probe_read_kernel_common() helper and provide a prototype for that, > to ensure this is compatible with both definitions. > > Cc: stable@vger.kernel.org > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Yonghong Song <yhs@fb.com>
On 6/2/23 3:50 PM, 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. > > Change the core.c file to only reference the inner > bpf_probe_read_kernel_common() helper and provide a prototype for that, > to ensure this is compatible with both definitions. > > Cc: stable@vger.kernel.org > Signed-off-by: Arnd Bergmann <arnd@arndb.de> Sorry for the delay. I just took in patch 1/2, thanks! Small comment below: > -- > v3: clarify changelog text further. > v2: rewrite completely to fix the mismatch. > --- > include/linux/bpf.h | 2 ++ > kernel/bpf/core.c | 9 ++++++--- > kernel/trace/bpf_trace.c | 3 +-- > 3 files changed, 9 insertions(+), 5 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index f58895830adae..55826398acfba 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2619,6 +2619,8 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) > } > #endif /* CONFIG_BPF_SYSCALL */ > > +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr); > + > void __bpf_free_used_btfs(struct bpf_prog_aux *aux, > struct btf_mod_pair *used_btfs, u32 len); > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index 0926714641eb5..565ef6950c7a8 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -35,6 +35,7 @@ > #include <linux/bpf_verifier.h> > #include <linux/nodemask.h> > #include <linux/nospec.h> > +#include <linux/bpf.h> > #include <linux/bpf_mem_alloc.h> > #include <linux/memcontrol.h> > > @@ -1635,11 +1636,13 @@ bool bpf_opcode_in_insntable(u8 code) > } > > #ifndef CONFIG_BPF_JIT_ALWAYS_ON > -u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) > +#ifndef CONFIG_BPF_EVENTS > +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) > { > memset(dst, 0, size); > return -EFAULT; > } > +#endif > > /** > * ___bpf_prog_run - run eBPF program on a given context > @@ -1931,8 +1934,8 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) > 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; > > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > index 2bc41e6ac9fe0..290fdce2ce535 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -223,8 +223,7 @@ const struct bpf_func_proto bpf_probe_read_user_str_proto = { > .arg3_type = ARG_ANYTHING, > }; > > -static __always_inline int > -bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) > +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) > { > int ret; Given this is critical fast-path, please find a solution where we don't need to penalize bpf_probe_read_kernel_common. Thanks, Daniel
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index f58895830adae..55826398acfba 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2619,6 +2619,8 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) } #endif /* CONFIG_BPF_SYSCALL */ +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr); + void __bpf_free_used_btfs(struct bpf_prog_aux *aux, struct btf_mod_pair *used_btfs, u32 len); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 0926714641eb5..565ef6950c7a8 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -35,6 +35,7 @@ #include <linux/bpf_verifier.h> #include <linux/nodemask.h> #include <linux/nospec.h> +#include <linux/bpf.h> #include <linux/bpf_mem_alloc.h> #include <linux/memcontrol.h> @@ -1635,11 +1636,13 @@ bool bpf_opcode_in_insntable(u8 code) } #ifndef CONFIG_BPF_JIT_ALWAYS_ON -u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) +#ifndef CONFIG_BPF_EVENTS +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) { memset(dst, 0, size); return -EFAULT; } +#endif /** * ___bpf_prog_run - run eBPF program on a given context @@ -1931,8 +1934,8 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) 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; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 2bc41e6ac9fe0..290fdce2ce535 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -223,8 +223,7 @@ const struct bpf_func_proto bpf_probe_read_user_str_proto = { .arg3_type = ARG_ANYTHING, }; -static __always_inline int -bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) +int bpf_probe_read_kernel_common(void *dst, u32 size, const void *unsafe_ptr) { int ret;