From f035a51536af9802f55d8c79bd87f184ebffb093 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 9 Sep 2016 02:45:29 +0200 Subject: bpf: add BPF_SIZEOF and BPF_FIELD_SIZEOF macros Add BPF_SIZEOF() and BPF_FIELD_SIZEOF() macros to improve the code a bit which otherwise often result in overly long bytes_to_bpf_size(sizeof()) and bytes_to_bpf_size(FIELD_SIZEOF()) lines. So place them into a macro helper instead. Moreover, we currently have a BUILD_BUG_ON(BPF_FIELD_SIZEOF()) check in convert_bpf_extensions(), but we should rather make that generic as well and add a BUILD_BUG_ON() test in all BPF_SIZEOF()/BPF_FIELD_SIZEOF() users to detect any rewriter size issues at compile time. Note, there are currently none, but we want to assert that it stays this way. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/filter.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'include/linux') diff --git a/include/linux/filter.h b/include/linux/filter.h index a16439b99fd9..7fabad8dc3fc 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -314,6 +314,20 @@ struct bpf_prog_aux; bpf_size; \ }) +#define BPF_SIZEOF(type) \ + ({ \ + const int __size = bytes_to_bpf_size(sizeof(type)); \ + BUILD_BUG_ON(__size < 0); \ + __size; \ + }) + +#define BPF_FIELD_SIZEOF(type, field) \ + ({ \ + const int __size = bytes_to_bpf_size(FIELD_SIZEOF(type, field)); \ + BUILD_BUG_ON(__size < 0); \ + __size; \ + }) + #ifdef CONFIG_COMPAT /* A struct sock_filter is architecture independent. */ struct compat_sock_fprog { -- cgit v1.2.3 From f3694e00123802d688180e7ae90b240669910e3c Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 9 Sep 2016 02:45:31 +0200 Subject: bpf: add BPF_CALL_x macros for declaring helpers This work adds BPF_CALL_() macros and converts all the eBPF helper functions to use them, in a similar fashion like we do with SYSCALL_DEFINE() macros that are used today. Motivation for this is to hide all the register handling and all necessary casts from the user, so that it is done automatically in the background when adding a BPF_CALL_() call. This makes current helpers easier to review, eases to write future helpers, avoids getting the casting mess wrong, and allows for extending all helpers at once (f.e. build time checks, etc). It also helps detecting more easily in code reviews that unused registers are not instrumented in the code by accident, breaking compatibility with existing programs. BPF_CALL_() internals are quite similar to SYSCALL_DEFINE() ones with some fundamental differences, for example, for generating the actual helper function that carries all u64 regs, we need to fill unused regs, so that we always end up with 5 u64 regs as an argument. I reviewed several 0-5 generated BPF_CALL_() variants of the .i results and they look all as expected. No sparse issue spotted. We let this also sit for a few days with Fengguang's kbuild test robot, and there were no issues seen. On s390, it barked on the "uses dynamic stack allocation" notice, which is an old one from bpf_perf_event_output{,_tp}() reappearing here due to the conversion to the call wrapper, just telling that the perf raw record/frag sits on stack (gcc with s390's -mwarn-dynamicstack), but that's all. Did various runtime tests and they were fine as well. All eBPF helpers are now converted to use these macros, getting rid of a good chunk of all the raw castings. Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: David S. Miller --- include/linux/filter.h | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) (limited to 'include/linux') diff --git a/include/linux/filter.h b/include/linux/filter.h index 7fabad8dc3fc..1f09c521adfe 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -328,6 +328,56 @@ struct bpf_prog_aux; __size; \ }) +#define __BPF_MAP_0(m, v, ...) v +#define __BPF_MAP_1(m, v, t, a, ...) m(t, a) +#define __BPF_MAP_2(m, v, t, a, ...) m(t, a), __BPF_MAP_1(m, v, __VA_ARGS__) +#define __BPF_MAP_3(m, v, t, a, ...) m(t, a), __BPF_MAP_2(m, v, __VA_ARGS__) +#define __BPF_MAP_4(m, v, t, a, ...) m(t, a), __BPF_MAP_3(m, v, __VA_ARGS__) +#define __BPF_MAP_5(m, v, t, a, ...) m(t, a), __BPF_MAP_4(m, v, __VA_ARGS__) + +#define __BPF_REG_0(...) __BPF_PAD(5) +#define __BPF_REG_1(...) __BPF_MAP(1, __VA_ARGS__), __BPF_PAD(4) +#define __BPF_REG_2(...) __BPF_MAP(2, __VA_ARGS__), __BPF_PAD(3) +#define __BPF_REG_3(...) __BPF_MAP(3, __VA_ARGS__), __BPF_PAD(2) +#define __BPF_REG_4(...) __BPF_MAP(4, __VA_ARGS__), __BPF_PAD(1) +#define __BPF_REG_5(...) __BPF_MAP(5, __VA_ARGS__) + +#define __BPF_MAP(n, ...) __BPF_MAP_##n(__VA_ARGS__) +#define __BPF_REG(n, ...) __BPF_REG_##n(__VA_ARGS__) + +#define __BPF_CAST(t, a) \ + (__force t) \ + (__force \ + typeof(__builtin_choose_expr(sizeof(t) == sizeof(unsigned long), \ + (unsigned long)0, (t)0))) a +#define __BPF_V void +#define __BPF_N + +#define __BPF_DECL_ARGS(t, a) t a +#define __BPF_DECL_REGS(t, a) u64 a + +#define __BPF_PAD(n) \ + __BPF_MAP(n, __BPF_DECL_ARGS, __BPF_N, u64, __ur_1, u64, __ur_2, \ + u64, __ur_3, u64, __ur_4, u64, __ur_5) + +#define BPF_CALL_x(x, name, ...) \ + static __always_inline \ + u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)); \ + u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)); \ + u64 name(__BPF_REG(x, __BPF_DECL_REGS, __BPF_N, __VA_ARGS__)) \ + { \ + return ____##name(__BPF_MAP(x,__BPF_CAST,__BPF_N,__VA_ARGS__));\ + } \ + static __always_inline \ + u64 ____##name(__BPF_MAP(x, __BPF_DECL_ARGS, __BPF_V, __VA_ARGS__)) + +#define BPF_CALL_0(name, ...) BPF_CALL_x(0, name, __VA_ARGS__) +#define BPF_CALL_1(name, ...) BPF_CALL_x(1, name, __VA_ARGS__) +#define BPF_CALL_2(name, ...) BPF_CALL_x(2, name, __VA_ARGS__) +#define BPF_CALL_3(name, ...) BPF_CALL_x(3, name, __VA_ARGS__) +#define BPF_CALL_4(name, ...) BPF_CALL_x(4, name, __VA_ARGS__) +#define BPF_CALL_5(name, ...) BPF_CALL_x(5, name, __VA_ARGS__) + #ifdef CONFIG_COMPAT /* A struct sock_filter is architecture independent. */ struct compat_sock_fprog { -- cgit v1.2.3