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bpf: use different interpreter depending on required stack size 

16 __bpf_prog_run() interpreters for various stack sizes add .text
but not a lot comparing to run-time stack savings

   text	   data	    bss	    dec	    hex	filename
  26350   10328     624   37302    91b6 kernel/bpf/core.o.before_split
  25777   10328     624   36729    8f79 kernel/bpf/core.o.after_split
  26970	  10328	    624	  37922	   9422	kernel/bpf/core.o.now

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2017-05-30 13:31:33 -07:00 committed by David S. Miller
parent 105c03614b
commit b870aa901f
1 changed files with 31 additions and 9 deletions
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40
kernel/bpf/core.c
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@ -1218,16 +1218,38 @@ static unsigned int ___bpf_prog_run(u64 *regs, const struct bpf_insn *insn,
}
STACK_FRAME_NON_STANDARD(___bpf_prog_run); /* jump table */
static unsigned int __bpf_prog_run(void *ctx, const struct bpf_insn *insn)
{
u64 stack[MAX_BPF_STACK / sizeof(u64)];
u64 regs[MAX_BPF_REG];
FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)];
ARG1 = (u64) (unsigned long) ctx;
return ___bpf_prog_run(regs, insn, stack);
#define PROG_NAME(stack_size) __bpf_prog_run##stack_size
#define DEFINE_BPF_PROG_RUN(stack_size) \
static unsigned int PROG_NAME(stack_size)(const void *ctx, const struct bpf_insn *insn) \
{ \
u64 stack[stack_size / sizeof(u64)]; \
u64 regs[MAX_BPF_REG]; \
\
FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)]; \
ARG1 = (u64) (unsigned long) ctx; \
return ___bpf_prog_run(regs, insn, stack); \
}
#define EVAL1(FN, X) FN(X)
#define EVAL2(FN, X, Y...) FN(X) EVAL1(FN, Y)
#define EVAL3(FN, X, Y...) FN(X) EVAL2(FN, Y)
#define EVAL4(FN, X, Y...) FN(X) EVAL3(FN, Y)
#define EVAL5(FN, X, Y...) FN(X) EVAL4(FN, Y)
#define EVAL6(FN, X, Y...) FN(X) EVAL5(FN, Y)
EVAL6(DEFINE_BPF_PROG_RUN, 32, 64, 96, 128, 160, 192);
EVAL6(DEFINE_BPF_PROG_RUN, 224, 256, 288, 320, 352, 384);
EVAL4(DEFINE_BPF_PROG_RUN, 416, 448, 480, 512);
#define PROG_NAME_LIST(stack_size) PROG_NAME(stack_size),
static unsigned int (*interpreters[])(const void *ctx,
const struct bpf_insn *insn) = {
EVAL6(PROG_NAME_LIST, 32, 64, 96, 128, 160, 192)
EVAL6(PROG_NAME_LIST, 224, 256, 288, 320, 352, 384)
EVAL4(PROG_NAME_LIST, 416, 448, 480, 512)
};
bool bpf_prog_array_compatible(struct bpf_array *array,
const struct bpf_prog *fp)
{
@ -1275,7 +1297,7 @@ static int bpf_check_tail_call(const struct bpf_prog *fp)
*/
struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
{
fp->bpf_func = (void *) __bpf_prog_run;
fp->bpf_func = interpreters[round_down(fp->aux->stack_depth, 32) / 32];
/* eBPF JITs can rewrite the program in case constant
* blinding is active. However, in case of error during