* [PATCH 1/1] x86/asm: Allow again using asm.h when building for the 'bpf' clang target
@ 2017-12-04 16:37 Arnaldo Carvalho de Melo
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From: Arnaldo Carvalho de Melo @ 2017-12-04 16:37 UTC (permalink / raw)
To: Josh Poimboeuf, Thomas Gleixner, Ingo Molnar
Cc: Adrian Hunter, Alexander Potapenko, Alexei Starovoitov,
Andrey Ryabinin, Andy Lutomirski, Arnd Bergmann, Daniel Borkmann,
David Ahern, Dmitriy Vyukov, Jiri Olsa, Linus Torvalds,
Matthias Kaehlcke, Miguel Bernal Marin, Namhyung Kim,
Peter Zijlstra, Wang Nan, Yonghong Song,
Linux Kernel Mailing List
Up to f5caf621ee35 ("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.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
arch/x86/include/asm/asm.h | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/include/asm/asm.h b/arch/x86/include/asm/asm.h
index 219faaec51df..386a6900e206 100644
--- a/arch/x86/include/asm/asm.h
+++ b/arch/x86/include/asm/asm.h
@@ -136,6 +136,7 @@
#endif
#ifndef __ASSEMBLY__
+#ifndef __BPF__
/*
* This output constraint should be used for any inline asm which has a "call"
* instruction. Otherwise the asm may be inserted before the frame pointer
@@ -145,5 +146,6 @@
register unsigned long current_stack_pointer asm(_ASM_SP);
#define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
#endif
+#endif
#endif /* _ASM_X86_ASM_H */
--
2.13.6
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