From: Arnd Bergmann <[email protected]>
This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled,
but CONFIG_BPF_SYSCALL is enabled. When both are turned off, the
prototype is missing but the unused function is still compiled,
as seen from this W=1 warning:
kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
Add a matching #ifdef for the definition to leave it out.
Signed-off-by: Arnd Bergmann <[email protected]>
---
v3: fix incorrect changelog text
v2: change indentation to align arguments better. Still not great
as the line is just too long
---
kernel/bpf/core.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 7421487422d48..0926714641eb5 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2064,14 +2064,16 @@ EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
#undef PROG_NAME_LIST
#define PROG_NAME_LIST(stack_size) PROG_NAME_ARGS(stack_size),
-static u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
- const struct bpf_insn *insn) = {
+static __maybe_unused
+u64 (*interpreters_args[])(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5,
+ const struct bpf_insn *insn) = {
EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
#undef PROG_NAME_LIST
+#ifdef CONFIG_BPF_SYSCALL
void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
{
stack_depth = max_t(u32, stack_depth, 1);
@@ -2080,6 +2082,7 @@ void bpf_patch_call_args(struct bpf_insn *insn, u32 stack_depth)
__bpf_call_base_args;
insn->code = BPF_JMP | BPF_CALL_ARGS;
}
+#endif
#else
static unsigned int __bpf_prog_ret0_warn(const void *ctx,
--
2.39.2
From: Arnd Bergmann <[email protected]>
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: [email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
--
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;
--
2.39.2
On 6/2/23 6:50 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> 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: [email protected]
> Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Yonghong Song <[email protected]>
On 6/2/23 6:50 AM, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> This function is only used when CONFIG_BPF_JIT_ALWAYS_ON is disabled,
> but CONFIG_BPF_SYSCALL is enabled. When both are turned off, the
> prototype is missing but the unused function is still compiled,
> as seen from this W=1 warning:
>
> kernel/bpf/core.c:2075:6: error: no previous prototype for 'bpf_patch_call_args' [-Werror=missing-prototypes]
>
> Add a matching #ifdef for the definition to leave it out.
>
> Signed-off-by: Arnd Bergmann <[email protected]>
Acked-by: Yonghong Song <[email protected]>
On 6/2/23 3:50 PM, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
>
> 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: [email protected]
> Signed-off-by: Arnd Bergmann <[email protected]>
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