diff options
-rw-r--r-- | tools/lib/bpf/bpf_helpers.h | 24 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/exhandler_kern.c | 2 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/loop5.c | 1 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/profiler1.c | 1 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/pyperf.h | 2 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/progs/test_pkt_access.c | 2 |
6 files changed, 24 insertions, 8 deletions
diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h index bbae9a057bc8..fb04eaf367f1 100644 --- a/tools/lib/bpf/bpf_helpers.h +++ b/tools/lib/bpf/bpf_helpers.h @@ -76,6 +76,30 @@ #endif /* + * Compiler (optimization) barrier. + */ +#ifndef barrier +#define barrier() asm volatile("" ::: "memory") +#endif + +/* Variable-specific compiler (optimization) barrier. It's a no-op which makes + * compiler believe that there is some black box modification of a given + * variable and thus prevents compiler from making extra assumption about its + * value and potential simplifications and optimizations on this variable. + * + * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of + * a variable, making some code patterns unverifiable. Putting barrier_var() + * in place will ensure that cast is performed before the barrier_var() + * invocation, because compiler has to pessimistically assume that embedded + * asm section might perform some extra operations on that variable. + * + * This is a variable-specific variant of more global barrier(). + */ +#ifndef barrier_var +#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) +#endif + +/* * Helper macro to throw a compilation error if __bpf_unreachable() gets * built into the resulting code. This works given BPF back end does not * implement __builtin_trap(). This is useful to assert that certain paths diff --git a/tools/testing/selftests/bpf/progs/exhandler_kern.c b/tools/testing/selftests/bpf/progs/exhandler_kern.c index dd9b30a0f0fc..20d009e2d266 100644 --- a/tools/testing/selftests/bpf/progs/exhandler_kern.c +++ b/tools/testing/selftests/bpf/progs/exhandler_kern.c @@ -7,8 +7,6 @@ #include <bpf/bpf_tracing.h> #include <bpf/bpf_core_read.h> -#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) - char _license[] SEC("license") = "GPL"; unsigned int exception_triggered; diff --git a/tools/testing/selftests/bpf/progs/loop5.c b/tools/testing/selftests/bpf/progs/loop5.c index 913791923fa3..1b13f37f85ec 100644 --- a/tools/testing/selftests/bpf/progs/loop5.c +++ b/tools/testing/selftests/bpf/progs/loop5.c @@ -2,7 +2,6 @@ // Copyright (c) 2019 Facebook #include <linux/bpf.h> #include <bpf/bpf_helpers.h> -#define barrier() __asm__ __volatile__("": : :"memory") char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/profiler1.c b/tools/testing/selftests/bpf/progs/profiler1.c index 4df9088bfc00..fb6b13522949 100644 --- a/tools/testing/selftests/bpf/progs/profiler1.c +++ b/tools/testing/selftests/bpf/progs/profiler1.c @@ -1,6 +1,5 @@ // SPDX-License-Identifier: GPL-2.0 /* Copyright (c) 2020 Facebook */ -#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) #define UNROLL #define INLINE __always_inline #include "profiler.inc.h" diff --git a/tools/testing/selftests/bpf/progs/pyperf.h b/tools/testing/selftests/bpf/progs/pyperf.h index 5d3dc4d66d47..6c7b1fb268d6 100644 --- a/tools/testing/selftests/bpf/progs/pyperf.h +++ b/tools/testing/selftests/bpf/progs/pyperf.h @@ -171,8 +171,6 @@ struct process_frame_ctx { bool done; }; -#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) - static int process_frame_callback(__u32 i, struct process_frame_ctx *ctx) { int zero = 0; diff --git a/tools/testing/selftests/bpf/progs/test_pkt_access.c b/tools/testing/selftests/bpf/progs/test_pkt_access.c index 0558544e1ff0..5cd7c096f62d 100644 --- a/tools/testing/selftests/bpf/progs/test_pkt_access.c +++ b/tools/testing/selftests/bpf/progs/test_pkt_access.c @@ -14,8 +14,6 @@ #include <bpf/bpf_helpers.h> #include <bpf/bpf_endian.h> -#define barrier() __asm__ __volatile__("": : :"memory") - /* llvm will optimize both subprograms into exactly the same BPF assembly * * Disassembly of section .text: |