x86/asm: Allow again using asm.h when building for the 'bpf' clang target
Up to f5caf621 ("x86/asm: Fix inline asm call constraints for Clang") we were able to use x86 headers to build to the 'bpf' clang target, as done by the BPF code in tools/perf/. With that commit, we ended up with following failure for 'perf test LLVM', this is because "clang ... -target bpf ..." fails since 4.0 does not have bpf inline asm support and 6.0 does not recognize the register 'esp', fix it by guarding that part with an #ifndef __BPF__, that is defined by clang when building to the "bpf" target. # perf test -v LLVM 37: LLVM search and compile : 37.1: Basic BPF llvm compile : --- start --- test child forked, pid 25526 Kernel build dir is set to /lib/modules/4.14.0+/build set env: KBUILD_DIR=/lib/modules/4.14.0+/build unset env: KBUILD_OPTS include option is set to -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h set env: NR_CPUS=4 set env: LINUX_VERSION_CODE=0x40e00 set env: CLANG_EXEC=/usr/local/bin/clang set env: CLANG_OPTIONS=-xc set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h set env: WORKING_DIR=/lib/modules/4.14.0+/build set env: CLANG_SOURCE=- llvm compiling command template: echo '/* * bpf-script-example.c * Test basic LLVM building */ #ifndef LINUX_VERSION_CODE # error Need LINUX_VERSION_CODE # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig' #endif #define BPF_ANY 0 #define BPF_MAP_TYPE_ARRAY 2 #define BPF_FUNC_map_lookup_elem 1 #define BPF_FUNC_map_update_elem 2 static void *(*bpf_map_lookup_elem)(void *map, void *key) = (void *) BPF_FUNC_map_lookup_elem; static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) = (void *) BPF_FUNC_map_update_elem; struct bpf_map_def { unsigned int type; unsigned int key_size; unsigned int value_size; unsigned int max_entries; }; #define SEC(NAME) __attribute__((section(NAME), used)) struct bpf_map_def SEC("maps") flip_table = { .type = BPF_MAP_TYPE_ARRAY, .key_size = sizeof(int), .value_size = sizeof(int), .max_entries = 1, }; SEC("func=SyS_epoll_wait") int bpf_func__SyS_epoll_wait(void *ctx) { int ind =0; int *flag = bpf_map_lookup_elem(&flip_table, &ind); int new_flag; if (!flag) return 0; /* flip flag and store back */ new_flag = !*flag; bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY); return new_flag; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o - test child finished with 0 ---- end ---- LLVM search and compile subtest 0: Ok 37.2: kbuild searching : --- start --- test child forked, pid 25950 Kernel build dir is set to /lib/modules/4.14.0+/build set env: KBUILD_DIR=/lib/modules/4.14.0+/build unset env: KBUILD_OPTS include option is set to -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h set env: NR_CPUS=4 set env: LINUX_VERSION_CODE=0x40e00 set env: CLANG_EXEC=/usr/local/bin/clang set env: CLANG_OPTIONS=-xc set env: KERNEL_INC_OPTIONS= -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/include/generated -I/home/acme/git/linux/include -I./include -I/home/acme/git/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/linux/include/linux/kconfig.h set env: WORKING_DIR=/lib/modules/4.14.0+/build set env: CLANG_SOURCE=- llvm compiling command template: echo '/* * bpf-script-test-kbuild.c * Test include from kernel header */ #ifndef LINUX_VERSION_CODE # error Need LINUX_VERSION_CODE # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig' #endif #define SEC(NAME) __attribute__((section(NAME), used)) #include <uapi/linux/fs.h> #include <uapi/asm/ptrace.h> SEC("func=vfs_llseek") int bpf_func__vfs_llseek(void *ctx) { return 0; } char _license[] SEC("license") = "GPL"; int _version SEC("version") = LINUX_VERSION_CODE; ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=$NR_CPUS -DLINUX_VERSION_CODE=$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-value -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -target bpf -O2 -o - In file included from <stdin>:12: In file included from /home/acme/git/linux/arch/x86/include/uapi/asm/ptrace.h:5: In file included from /home/acme/git/linux/include/linux/compiler.h:242: In file included from /home/acme/git/linux/arch/x86/include/asm/barrier.h:5: In file included from /home/acme/git/linux/arch/x86/include/asm/alternative.h:10: /home/acme/git/linux/arch/x86/include/asm/asm.h:145:50: error: unknown register name 'esp' in asm register unsigned long current_stack_pointer asm(_ASM_SP); ^ /home/acme/git/linux/arch/x86/include/asm/asm.h:44:18: note: expanded from macro '_ASM_SP' #define _ASM_SP __ASM_REG(sp) ^ /home/acme/git/linux/arch/x86/include/asm/asm.h:27:32: note: expanded from macro '__ASM_REG' #define __ASM_REG(reg) __ASM_SEL_RAW(e##reg, r##reg) ^ /home/acme/git/linux/arch/x86/include/asm/asm.h:18:29: note: expanded from macro '__ASM_SEL_RAW' # define __ASM_SEL_RAW(a,b) __ASM_FORM_RAW(a) ^ /home/acme/git/linux/arch/x86/include/asm/asm.h:11:32: note: expanded from macro '__ASM_FORM_RAW' # define __ASM_FORM_RAW(x) #x ^ <scratch space>:4:1: note: expanded from here "esp" ^ 1 error generated. ERROR: unable to compile - Hint: Check error message shown above. Hint: You can also pre-compile it into .o using: clang -target bpf -O2 -c - with proper -I and -D options. Failed to compile test case: 'kbuild searching' test child finished with -1 ---- end ---- LLVM search and compile subtest 1: FAILED! Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: David Ahern <dsahern@gmail.com> Cc: Dmitriy Vyukov <dvyukov@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wang Nan <wangnan0@huawei.com> Cc: Yonghong Song <yhs@fb.com> Link: https://lkml.kernel.org/r/20171128175948.GL3298@kernel.orgSigned-off-by: NArnaldo Carvalho de Melo <acme@redhat.com>
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