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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Arnaldo Carvalho de Melo <acme@redhat.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Alexander Potapenko <glider@google.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Andy Lutomirski <luto@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Daniel Borkmann <daniel@iogearbox.net>,
        David Ahern <dsahern@gmail.com>,
        Dmitriy Vyukov <dvyukov@google.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        Miguel Bernal Marin <miguel.bernal.marin@linux.intel.com>,
        Namhyung Kim <namhyung@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Wang Nan <wangnan0@huawei.com>, Yonghong Song <yhs@fb.com>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 018/110] x86/asm: Allow again using asm.h
 when building for the 'bpf' clang target
Thread-Topic: [PATCH AUTOSEL for 4.14 018/110] x86/asm: Allow again using
 asm.h when building for the 'bpf' clang target
Thread-Index: AQHTnRjkKnWfU7jMuEWm/uCdtOyT2g==
Date:   Sat, 3 Feb 2018 18:00:36 +0000
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From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit ca26cffa4e4aaeb09bb9e308f95c7835cb149248 ]

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 in=
line
asm support and 6.0 does not recognize the register 'esp', fix it by guardi=
ng
that part with an #ifndef __BPF__, that is defined by clang when building t=
o
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=3D/lib/modules/4.14.0+/build
  unset env: KBUILD_OPTS
  include option is set to  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-l=
inux/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/lin=
ux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/g=
it/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/li=
nux/include/linux/kconfig.h
  set env: NR_CPUS=3D4
  set env: LINUX_VERSION_CODE=3D0x40e00
  set env: CLANG_EXEC=3D/usr/local/bin/clang
  set env: CLANG_OPTIONS=3D-xc
  set env: KERNEL_INC_OPTIONS=3D -nostdinc -isystem /usr/lib/gcc/x86_64-red=
hat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/in=
clude/generated  -I/home/acme/git/linux/include -I./include -I/home/acme/gi=
t/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/a=
cme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/g=
it/linux/include/linux/kconfig.h
  set env: WORKING_DIR=3D/lib/modules/4.14.0+/build
  set env: CLANG_SOURCE=3D-
  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=3D"-DLINUX_VERSION_CODE=
=3D0x40200" 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) =3D
	  (void *) BPF_FUNC_map_lookup_elem;
  static void *(*bpf_map_update_elem)(void *map, void *key, void *value, in=
t flags) =3D
	  (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 =3D {
	  .type =3D BPF_MAP_TYPE_ARRAY,
	  .key_size =3D sizeof(int),
	  .value_size =3D sizeof(int),
	  .max_entries =3D 1,
  };

  SEC("func=3DSyS_epoll_wait")
  int bpf_func__SyS_epoll_wait(void *ctx)
  {
	  int ind =3D0;
	  int *flag =3D bpf_map_lookup_elem(&flip_table, &ind);
	  int new_flag;
	  if (!flag)
		  return 0;
	  /* flip flag and store back */
	  new_flag =3D !*flag;
	  bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
	  return new_flag;
  }
  char _license[] SEC("license") =3D "GPL";
  int _version SEC("version") =3D LINUX_VERSION_CODE;
  ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=3D$NR_CPUS -DLINUX_VERSION_COD=
E=3D$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-valu=
e -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -tar=
get 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=3D/lib/modules/4.14.0+/build
  unset env: KBUILD_OPTS
  include option is set to  -nostdinc -isystem /usr/lib/gcc/x86_64-redhat-l=
inux/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/lin=
ux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/acme/g=
it/linux/include/uapi -I./include/generated/uapi -include /home/acme/git/li=
nux/include/linux/kconfig.h
  set env: NR_CPUS=3D4
  set env: LINUX_VERSION_CODE=3D0x40e00
  set env: CLANG_EXEC=3D/usr/local/bin/clang
  set env: CLANG_OPTIONS=3D-xc
  set env: KERNEL_INC_OPTIONS=3D -nostdinc -isystem /usr/lib/gcc/x86_64-red=
hat-linux/7/include -I/home/acme/git/linux/arch/x86/include -I./arch/x86/in=
clude/generated  -I/home/acme/git/linux/include -I./include -I/home/acme/gi=
t/linux/arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I/home/a=
cme/git/linux/include/uapi -I./include/generated/uapi -include /home/acme/g=
it/linux/include/linux/kconfig.h
  set env: WORKING_DIR=3D/lib/modules/4.14.0+/build
  set env: CLANG_SOURCE=3D-
  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=3D"-DLINUX_VERSION_CODE=
=3D0x40200" 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=3Dvfs_llseek")
  int bpf_func__vfs_llseek(void *ctx)
  {
	  return 0;
  }

  char _license[] SEC("license") =3D "GPL";
  int _version SEC("version") =3D LINUX_VERSION_CODE;
  ' | $CLANG_EXEC -D__KERNEL__ -D__NR_CPUS__=3D$NR_CPUS -DLINUX_VERSION_COD=
E=3D$LINUX_VERSION_CODE $CLANG_OPTIONS $KERNEL_INC_OPTIONS -Wno-unused-valu=
e -Wno-pointer-sign -working-directory $WORKING_DIR -c "$CLANG_SOURCE" -tar=
get bpf -O2 -o -
  In file included from <stdin>:12:
  In file included from /home/acme/git/linux/arch/x86/include/uapi/asm/ptra=
ce.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/alternati=
ve.h:10:
  /home/acme/git/linux/arch/x86/include/asm/asm.h:145:50: error: unknown re=
gister 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 fro=
m macro '_ASM_SP'
  #define _ASM_SP         __ASM_REG(sp)
                          ^
  /home/acme/git/linux/arch/x86/include/asm/asm.h:27:32: note: expanded fro=
m 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 fro=
m 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 fro=
m 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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.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
=20
 #ifndef __ASSEMBLY__
+#ifndef __BPF__
 /*
  * This output constraint should be used for any inline asm which has a "c=
all"
  * instruction.  Otherwise the asm may be inserted before the frame pointe=
r
@@ -145,5 +146,6 @@
 register unsigned long current_stack_pointer asm(_ASM_SP);
 #define ASM_CALL_CONSTRAINT "+r" (current_stack_pointer)
 #endif
+#endif
=20
 #endif /* _ASM_X86_ASM_H */
--=20
2.11.0