On Fri, Sep 10, 2021 at 11:19 AM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote: > > The tailcall_3 test program uses bpf_tail_call_static() where the JIT > would patch a direct jump. Add a new tailcall_6 test program replicating > exactly the same test just ensuring that bpf_tail_call() uses a map > index where the verifier cannot make assumptions this time. > > In other words, this will now cover both on x86-64 JIT, meaning, JIT > images with emit_bpf_tail_call_direct() emission as well as JIT images > with emit_bpf_tail_call_indirect() emission. > > # echo 1 > /proc/sys/net/core/bpf_jit_enable > # ./test_progs -t tailcalls > #136/1 tailcalls/tailcall_1:OK > #136/2 tailcalls/tailcall_2:OK > #136/3 tailcalls/tailcall_3:OK > #136/4 tailcalls/tailcall_4:OK > #136/5 tailcalls/tailcall_5:OK > #136/6 tailcalls/tailcall_6:OK > #136/7 tailcalls/tailcall_bpf2bpf_1:OK > #136/8 tailcalls/tailcall_bpf2bpf_2:OK > #136/9 tailcalls/tailcall_bpf2bpf_3:OK > #136/10 tailcalls/tailcall_bpf2bpf_4:OK > #136/11 tailcalls/tailcall_bpf2bpf_5:OK > #136 tailcalls:OK > Summary: 1/11 PASSED, 0 SKIPPED, 0 FAILED > > # echo 0 > /proc/sys/net/core/bpf_jit_enable > # ./test_progs -t tailcalls > #136/1 tailcalls/tailcall_1:OK > #136/2 tailcalls/tailcall_2:OK > #136/3 tailcalls/tailcall_3:OK > #136/4 tailcalls/tailcall_4:OK > #136/5 tailcalls/tailcall_5:OK > #136/6 tailcalls/tailcall_6:OK > [...] > > For interpreter, the tailcall_1-6 tests are passing as well. The later > tailcall_bpf2bpf_* are failing due lack of bpf2bpf + tailcall support > in interpreter, so this is expected. > > Also, manual inspection shows that both loaded programs from tailcall_3 > and tailcall_6 test case emit the expected opcodes: > > * tailcall_3 disasm, emit_bpf_tail_call_direct(): > > [...] > b: push %rax > c: push %rbx > d: push %r13 > f: mov %rdi,%rbx > 12: movabs $0xffff8d3f5afb0200,%r13 > 1c: mov %rbx,%rdi > 1f: mov %r13,%rsi > 22: xor %edx,%edx _ > 24: mov -0x4(%rbp),%eax | limit check > 2a: cmp $0x20,%eax | > 2d: ja 0x0000000000000046 | > 2f: add $0x1,%eax | > 32: mov %eax,-0x4(%rbp) |_ > 38: nopl 0x0(%rax,%rax,1) > 3d: pop %r13 > 3f: pop %rbx > 40: pop %rax > 41: jmpq 0xffffffffffffe377 > [...] > > * tailcall_6 disasm, emit_bpf_tail_call_indirect(): > > [...] > 47: movabs $0xffff8d3f59143a00,%rsi > 51: mov %edx,%edx > 53: cmp %edx,0x24(%rsi) > 56: jbe 0x0000000000000093 _ > 58: mov -0x4(%rbp),%eax | limit check > 5e: cmp $0x20,%eax | > 61: ja 0x0000000000000093 | > 63: add $0x1,%eax | > 66: mov %eax,-0x4(%rbp) |_ > 6c: mov 0x110(%rsi,%rdx,8),%rcx > 74: test %rcx,%rcx > 77: je 0x0000000000000093 > 79: pop %rax > 7a: mov 0x30(%rcx),%rcx > 7e: add $0xb,%rcx > 82: callq 0x000000000000008e > 87: pause > 89: lfence > 8c: jmp 0x0000000000000087 > 8e: mov %rcx,(%rsp) > 92: retq > [...] > > Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx> > Cc: Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx> > Cc: Paul Chaignon <paul@xxxxxxxxx> > Cc: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> > Link: https://lore.kernel.org/bpf/CAM1=_QRyRVCODcXo_Y6qOm1iT163HoiSj8U2pZ8Rj3hzMTT=HQ@xxxxxxxxxxxxxx > --- > [ Cooked up proper patch for it after manual inspection as I think > it's useful in any case to have the coverage for both JIT code > generation cases. ] > > .../selftests/bpf/prog_tests/tailcalls.c | 25 +++++++++++--- > tools/testing/selftests/bpf/progs/tailcall6.c | 34 +++++++++++++++++++ > 2 files changed, 54 insertions(+), 5 deletions(-) > create mode 100644 tools/testing/selftests/bpf/progs/tailcall6.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/tailcalls.c b/tools/testing/selftests/bpf/prog_tests/tailcalls.c > index b5940e6ca67c..7bf3a7a97d7b 100644 > --- a/tools/testing/selftests/bpf/prog_tests/tailcalls.c > +++ b/tools/testing/selftests/bpf/prog_tests/tailcalls.c > @@ -219,10 +219,7 @@ static void test_tailcall_2(void) > bpf_object__close(obj); > } > > -/* test_tailcall_3 checks that the count value of the tail call limit > - * enforcement matches with expectations. > - */ > -static void test_tailcall_3(void) > +static void test_tailcall_count(const char *which) > { > int err, map_fd, prog_fd, main_fd, data_fd, i, val; > struct bpf_map *prog_array, *data_map; > @@ -231,7 +228,7 @@ static void test_tailcall_3(void) > __u32 retval, duration; > char buff[128] = {}; > > - err = bpf_prog_load("tailcall3.o", BPF_PROG_TYPE_SCHED_CLS, &obj, > + err = bpf_prog_load(which, BPF_PROG_TYPE_SCHED_CLS, &obj, > &prog_fd); > if (CHECK_FAIL(err)) > return; > @@ -296,6 +293,22 @@ static void test_tailcall_3(void) > bpf_object__close(obj); > } > > +/* test_tailcall_3 checks that the count value of the tail call limit > + * enforcement matches with expectations. JIT uses direct jump. > + */ > +static void test_tailcall_3(void) > +{ > + test_tailcall_count("tailcall3.o"); > +} > + > +/* test_tailcall_6 checks that the count value of the tail call limit > + * enforcement matches with expectations. JIT uses indirect jump. > + */ > +static void test_tailcall_6(void) > +{ > + test_tailcall_count("tailcall6.o"); > +} > + > /* test_tailcall_4 checks that the kernel properly selects indirect jump > * for the case where the key is not known. Latter is passed via global > * data to select different targets we can compare return value of. > @@ -822,6 +835,8 @@ void test_tailcalls(void) > test_tailcall_4(); > if (test__start_subtest("tailcall_5")) > test_tailcall_5(); > + if (test__start_subtest("tailcall_6")) > + test_tailcall_6(); > if (test__start_subtest("tailcall_bpf2bpf_1")) > test_tailcall_bpf2bpf_1(); > if (test__start_subtest("tailcall_bpf2bpf_2")) > diff --git a/tools/testing/selftests/bpf/progs/tailcall6.c b/tools/testing/selftests/bpf/progs/tailcall6.c > new file mode 100644 > index 000000000000..0f4a811cc028 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/tailcall6.c > @@ -0,0 +1,34 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include <linux/bpf.h> > + > +#include <bpf/bpf_helpers.h> > + > +struct { > + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); > + __uint(max_entries, 1); > + __uint(key_size, sizeof(__u32)); > + __uint(value_size, sizeof(__u32)); > +} jmp_table SEC(".maps"); > + > +int count, which; > + > +SEC("classifier/0") > +int bpf_func_0(struct __sk_buff *skb) > +{ > + count++; > + if (__builtin_constant_p(which)) > + __bpf_unreachable(); > + bpf_tail_call(skb, &jmp_table, which); > + return 1; > +} > + > +SEC("classifier") > +int entry(struct __sk_buff *skb) > +{ > + if (__builtin_constant_p(which)) > + __bpf_unreachable(); > + bpf_tail_call(skb, &jmp_table, which); > + return 0; > +} > + > +char __license[] SEC("license") = "GPL"; > -- > 2.27.0 > Acked-by: Johan Almbladh <johan.almbladh@xxxxxxxxxxxxxxxxx>
