| Message ID | E1fcrsq-0005V7-Pp@rmk-PC.armlinux.org.uk |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | ARM BPF jit compiler improvements | expand |
Hi Russell,
I love your patch! Yet something to improve:
[auto build test ERROR on net-next/master]
url: https://github.com/0day-ci/linux/commits/Russell-King/ARM-net-bpf-enumerate-the-JIT-scratch-stack-layout/20180710-203859
config: arm-allmodconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.2.0 make.cross ARCH=arm
All error/warnings (new ones prefixed by >>):
In file included from include/linux/kernel.h:10:0,
from include/linux/list.h:9,
from include/linux/timer.h:5,
from include/linux/workqueue.h:9,
from include/linux/bpf.h:12,
from arch/arm/net/bpf_jit_32.c:12:
In function 'emit_bpf_tail_call',
inlined from 'build_insn' at arch/arm/net/bpf_jit_32.c:1601:7:
>> include/linux/compiler.h:339:38: error: call to '__compiletime_assert_1045' declared with attribute error: BUILD_BUG_ON failed: offsetof(struct bpf_array, ptrs) > ARM_ALU_IMM
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
^
include/linux/compiler.h:319:4: note: in definition of macro '__compiletime_assert'
prefix ## suffix(); \
^~~~~~
include/linux/compiler.h:339:2: note: in expansion of macro '_compiletime_assert'
_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
^~~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:45:37: note: in expansion of macro 'compiletime_assert'
#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
^~~~~~~~~~~~~~~~~~
include/linux/build_bug.h:69:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
^~~~~~~~~~~~~~~~
>> arch/arm/net/bpf_jit_32.c:1045:2: note: in expansion of macro 'BUILD_BUG_ON'
BUILD_BUG_ON(offsetof(struct bpf_array, ptrs) > ARM_ALU_IMM);
^~~~~~~~~~~~
vim +/__compiletime_assert_1045 +339 include/linux/compiler.h
9a8ab1c3 Daniel Santos 2013-02-21 325
9a8ab1c3 Daniel Santos 2013-02-21 326 #define _compiletime_assert(condition, msg, prefix, suffix) \
9a8ab1c3 Daniel Santos 2013-02-21 327 __compiletime_assert(condition, msg, prefix, suffix)
9a8ab1c3 Daniel Santos 2013-02-21 328
9a8ab1c3 Daniel Santos 2013-02-21 329 /**
9a8ab1c3 Daniel Santos 2013-02-21 330 * compiletime_assert - break build and emit msg if condition is false
9a8ab1c3 Daniel Santos 2013-02-21 331 * @condition: a compile-time constant condition to check
9a8ab1c3 Daniel Santos 2013-02-21 332 * @msg: a message to emit if condition is false
9a8ab1c3 Daniel Santos 2013-02-21 333 *
9a8ab1c3 Daniel Santos 2013-02-21 334 * In tradition of POSIX assert, this macro will break the build if the
9a8ab1c3 Daniel Santos 2013-02-21 335 * supplied condition is *false*, emitting the supplied error message if the
9a8ab1c3 Daniel Santos 2013-02-21 336 * compiler has support to do so.
9a8ab1c3 Daniel Santos 2013-02-21 337 */
9a8ab1c3 Daniel Santos 2013-02-21 338 #define compiletime_assert(condition, msg) \
9a8ab1c3 Daniel Santos 2013-02-21 @339 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
9a8ab1c3 Daniel Santos 2013-02-21 340
:::::: The code at line 339 was first introduced by commit
:::::: 9a8ab1c39970a4938a72d94e6fd13be88a797590 bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG
:::::: TO: Daniel Santos <daniel.santos@pobox.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>
---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation
diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 753b5b2b2e3d..c7591877c350 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -256,7 +256,7 @@ static u32 arm_bpf_ldst_imm12(u32 op, u8 rt, u8 rn, s16 imm12) op |= ARM_INST_LDST__U; else imm12 = -imm12; - return op | (imm12 & 0xfff); + return op | (imm12 & ARM_INST_LDST__IMM12); } static u32 arm_bpf_ldst_imm8(u32 op, u8 rt, u8 rn, s16 imm8) @@ -1012,11 +1012,12 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) /* if (index >= array->map.max_entries) * goto out; */ + BUILD_BUG_ON(offsetof(struct bpf_array, map.max_entries) > + ARM_INST_LDST__IMM12); off = offsetof(struct bpf_array, map.max_entries); /* array->map.max_entries */ - emit_a32_mov_i(tmp[1], off, ctx); r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); - emit(ARM_LDR_R(tmp[1], r_array, tmp[1]), ctx); + emit(ARM_LDR_I(tmp[1], r_array, off), ctx); /* index is 32-bit for arrays */ r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); /* index >= array->map.max_entries */ @@ -1041,10 +1042,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) * if (prog == NULL) * goto out; */ + BUILD_BUG_ON(offsetof(struct bpf_array, ptrs) > ARM_ALU_IMM); off = offsetof(struct bpf_array, ptrs); - emit_a32_mov_i(tmp[1], off, ctx); r_array = arm_bpf_get_reg32(r2[1], tmp2[1], ctx); - emit(ARM_ADD_R(tmp[1], r_array, tmp[1]), ctx); + emit(ARM_ADD_I(tmp[1], r_array, off), ctx); r_index = arm_bpf_get_reg32(r3[1], tmp2[1], ctx); emit(ARM_MOV_SI(tmp[0], r_index, SRTYPE_ASL, 2), ctx); emit(ARM_LDR_R(tmp[1], tmp[1], tmp[0]), ctx); @@ -1052,9 +1053,10 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx) _emit(ARM_COND_EQ, ARM_B(jmp_offset), ctx); /* goto *(prog->bpf_func + prologue_size); */ + BUILD_BUG_ON(offsetof(struct bpf_prog, bpf_func) > + ARM_INST_LDST__IMM12); off = offsetof(struct bpf_prog, bpf_func); - emit_a32_mov_i(tmp2[1], off, ctx); - emit(ARM_LDR_R(tmp[1], tmp[1], tmp2[1]), ctx); + emit(ARM_LDR_I(tmp[1], tmp[1], off), ctx); emit(ARM_ADD_I(tmp[1], tmp[1], ctx->prologue_bytes), ctx); emit_bx_r(tmp[1], ctx); diff --git a/arch/arm/net/bpf_jit_32.h b/arch/arm/net/bpf_jit_32.h index c55bc39d3e22..ca9f1f5589f4 100644 --- a/arch/arm/net/bpf_jit_32.h +++ b/arch/arm/net/bpf_jit_32.h @@ -78,6 +78,7 @@ #define ARM_INST_EOR_I 0x02200000 #define ARM_INST_LDST__U 0x00800000 +#define ARM_INST_LDST__IMM12 0x00000fff #define ARM_INST_LDRB_I 0x05500000 #define ARM_INST_LDRB_R 0x07d00000 #define ARM_INST_LDRH_I 0x015000b0 @@ -154,6 +155,8 @@ */ #define ARM_INST_UDF 0xe7fddef1 +#define ARM_ALU_IMM 0xff + /* register */ #define _AL3_R(op, rd, rn, rm) ((op ## _R) | (rd) << 12 | (rn) << 16 | (rm)) /* immediate */
Rather than moving constants to a register and then using them in a subsequent instruction, use them directly in the desired instruction cutting out the "middle" register. This removes two instructions from the tail call code path. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> --- arch/arm/net/bpf_jit_32.c | 16 +++++++++------- arch/arm/net/bpf_jit_32.h | 3 +++ 2 files changed, 12 insertions(+), 7 deletions(-)