| Message ID | 20230725204149.3411961-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v4] bpf: fix bpf_probe_read_kernel prototype mismatch | expand |
On 7/25/23 1:41 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. > > 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> LGTM but there are some additional changes in kernel so you need to rebase on top of master branch with the following additional change: @@ -2082,7 +2076,7 @@ static u64 ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn) 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; Thanks! > -- > v4: rewrite again to use a shared inline helper > v3: clarify changelog text further. > v2: rewrite completely to fix the mismatch. > --- > include/linux/bpf.h | 12 ++++++++++++ > kernel/bpf/core.c | 10 ++-------- > kernel/trace/bpf_trace.c | 11 ----------- > 3 files changed, 14 insertions(+), 19 deletions(-) > > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index ceaa8c23287fc..abe75063630b8 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -2661,6 +2661,18 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) > } > #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); > > diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c > index dd70c58c9d3a3..9cdf53bfb8bd3 100644 > --- a/kernel/bpf/core.c > +++ b/kernel/bpf/core.c > @@ -1634,12 +1634,6 @@ 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) > -{ > - 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 > @@ -1930,8 +1924,8 @@ 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 c92eb8c6ff08d..83bde2475ae54 100644 > --- a/kernel/trace/bpf_trace.c > +++ b/kernel/trace/bpf_trace.c > @@ -223,17 +223,6 @@ 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 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) > {
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index ceaa8c23287fc..abe75063630b8 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -2661,6 +2661,18 @@ static inline void bpf_dynptr_set_rdonly(struct bpf_dynptr_kern *ptr) } #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); diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index dd70c58c9d3a3..9cdf53bfb8bd3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -1634,12 +1634,6 @@ 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) -{ - 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 @@ -1930,8 +1924,8 @@ 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 c92eb8c6ff08d..83bde2475ae54 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -223,17 +223,6 @@ 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 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) {