]> git.ipfire.org Git - thirdparty/linux.git/commitdiff
selftests/bpf: Test gen_prologue and gen_epilogue
authorMartin KaFai Lau <martin.lau@kernel.org>
Thu, 29 Aug 2024 21:08:28 +0000 (14:08 -0700)
committerAlexei Starovoitov <ast@kernel.org>
Fri, 30 Aug 2024 01:15:45 +0000 (18:15 -0700)
This test adds a new struct_ops "bpf_testmod_st_ops" in bpf_testmod.
The ops of the bpf_testmod_st_ops is triggered by new kfunc calls
"bpf_kfunc_st_ops_test_*logue". These new kfunc calls are
primarily used by the SEC("syscall") program. The test triggering
sequence is like:
    SEC("syscall")
    syscall_prologue(struct st_ops_args *args)
        bpf_kfunc_st_op_test_prologue(args)
    st_ops->test_prologue(args)

.gen_prologue adds 1000 to args->a
.gen_epilogue adds 10000 to args->a
.gen_epilogue will also set the r0 to 2 * args->a.

The .gen_prologue and .gen_epilogue of the bpf_testmod_st_ops
will test the prog->aux->attach_func_name to decide if
it needs to generate codes.

The main programs of the pro_epilogue.c will call a
new kfunc bpf_kfunc_st_ops_inc10 which does "args->a += 10".
It will also call a subprog() which does "args->a += 1".

This patch uses the test_loader infra to check the __xlated
instructions patched after gen_prologue and/or gen_epilogue.
The __xlated check is based on Eduard's example (Thanks!) in v1.

args->a is returned by the struct_ops prog (either the main prog
or the epilogue). Thus, the __retval of the SEC("syscall") prog
is checked. For example, when triggering the ops in the
'SEC("struct_ops/test_epilogue") int test_epilogue'
The expected args->a is +1 (subprog call) + 10 (kfunc call)
                 + 10000 (.gen_epilogue) = 10011.
The expected return value is 2 * 10011 (.gen_epilogue).

Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240829210833.388152-7-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.h
tools/testing/selftests/bpf/bpf_testmod/bpf_testmod_kfunc.h
tools/testing/selftests/bpf/prog_tests/pro_epilogue.c [new file with mode: 0644]
tools/testing/selftests/bpf/progs/pro_epilogue.c [new file with mode: 0644]

index 8a71a91b752deeae2b8baf267f72a2e83be11ea3..42c38dbb6835dce790e70a125af9326999437867 100644 (file)
@@ -17,6 +17,7 @@
 #include <linux/in.h>
 #include <linux/in6.h>
 #include <linux/un.h>
+#include <linux/filter.h>
 #include <net/sock.h>
 #include <linux/namei.h>
 #include "bpf_testmod.h"
@@ -945,6 +946,51 @@ out:
        return err;
 }
 
+static DEFINE_MUTEX(st_ops_mutex);
+static struct bpf_testmod_st_ops *st_ops;
+
+__bpf_kfunc int bpf_kfunc_st_ops_test_prologue(struct st_ops_args *args)
+{
+       int ret = -1;
+
+       mutex_lock(&st_ops_mutex);
+       if (st_ops && st_ops->test_prologue)
+               ret = st_ops->test_prologue(args);
+       mutex_unlock(&st_ops_mutex);
+
+       return ret;
+}
+
+__bpf_kfunc int bpf_kfunc_st_ops_test_epilogue(struct st_ops_args *args)
+{
+       int ret = -1;
+
+       mutex_lock(&st_ops_mutex);
+       if (st_ops && st_ops->test_epilogue)
+               ret = st_ops->test_epilogue(args);
+       mutex_unlock(&st_ops_mutex);
+
+       return ret;
+}
+
+__bpf_kfunc int bpf_kfunc_st_ops_test_pro_epilogue(struct st_ops_args *args)
+{
+       int ret = -1;
+
+       mutex_lock(&st_ops_mutex);
+       if (st_ops && st_ops->test_pro_epilogue)
+               ret = st_ops->test_pro_epilogue(args);
+       mutex_unlock(&st_ops_mutex);
+
+       return ret;
+}
+
+__bpf_kfunc int bpf_kfunc_st_ops_inc10(struct st_ops_args *args)
+{
+       args->a += 10;
+       return args->a;
+}
+
 BTF_KFUNCS_START(bpf_testmod_check_kfunc_ids)
 BTF_ID_FLAGS(func, bpf_testmod_test_mod_kfunc)
 BTF_ID_FLAGS(func, bpf_kfunc_call_test1)
@@ -981,6 +1027,10 @@ BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_sendmsg, KF_SLEEPABLE)
 BTF_ID_FLAGS(func, bpf_kfunc_call_sock_sendmsg, KF_SLEEPABLE)
 BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getsockname, KF_SLEEPABLE)
 BTF_ID_FLAGS(func, bpf_kfunc_call_kernel_getpeername, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_prologue, KF_TRUSTED_ARGS | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_epilogue, KF_TRUSTED_ARGS | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_kfunc_st_ops_test_pro_epilogue, KF_TRUSTED_ARGS | KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_kfunc_st_ops_inc10, KF_TRUSTED_ARGS)
 BTF_KFUNCS_END(bpf_testmod_check_kfunc_ids)
 
 static int bpf_testmod_ops_init(struct btf *btf)
@@ -1100,6 +1150,144 @@ struct bpf_struct_ops bpf_testmod_ops2 = {
        .owner = THIS_MODULE,
 };
 
+static int bpf_test_mod_st_ops__test_prologue(struct st_ops_args *args)
+{
+       return 0;
+}
+
+static int bpf_test_mod_st_ops__test_epilogue(struct st_ops_args *args)
+{
+       return 0;
+}
+
+static int bpf_test_mod_st_ops__test_pro_epilogue(struct st_ops_args *args)
+{
+       return 0;
+}
+
+static int st_ops_gen_prologue(struct bpf_insn *insn_buf, bool direct_write,
+                              const struct bpf_prog *prog)
+{
+       struct bpf_insn *insn = insn_buf;
+
+       if (strcmp(prog->aux->attach_func_name, "test_prologue") &&
+           strcmp(prog->aux->attach_func_name, "test_pro_epilogue"))
+               return 0;
+
+       /* r6 = r1[0]; // r6 will be "struct st_ops *args". r1 is "u64 *ctx".
+        * r7 = r6->a;
+        * r7 += 1000;
+        * r6->a = r7;
+        */
+       *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0);
+       *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_6, offsetof(struct st_ops_args, a));
+       *insn++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_7, 1000);
+       *insn++ = BPF_STX_MEM(BPF_DW, BPF_REG_6, BPF_REG_7, offsetof(struct st_ops_args, a));
+       *insn++ = prog->insnsi[0];
+
+       return insn - insn_buf;
+}
+
+static int st_ops_gen_epilogue(struct bpf_insn *insn_buf, const struct bpf_prog *prog,
+                              s16 ctx_stack_off)
+{
+       struct bpf_insn *insn = insn_buf;
+
+       if (strcmp(prog->aux->attach_func_name, "test_epilogue") &&
+           strcmp(prog->aux->attach_func_name, "test_pro_epilogue"))
+               return 0;
+
+       /* r1 = stack[ctx_stack_off]; // r1 will be "u64 *ctx"
+        * r1 = r1[0]; // r1 will be "struct st_ops *args"
+        * r6 = r1->a;
+        * r6 += 10000;
+        * r1->a = r6;
+        * r0 = r6;
+        * r0 *= 2;
+        * BPF_EXIT;
+        */
+       *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_FP, ctx_stack_off);
+       *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, 0);
+       *insn++ = BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, offsetof(struct st_ops_args, a));
+       *insn++ = BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 10000);
+       *insn++ = BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_6, offsetof(struct st_ops_args, a));
+       *insn++ = BPF_MOV64_REG(BPF_REG_0, BPF_REG_6);
+       *insn++ = BPF_ALU64_IMM(BPF_MUL, BPF_REG_0, 2);
+       *insn++ = BPF_EXIT_INSN();
+
+       return insn - insn_buf;
+}
+
+static int st_ops_btf_struct_access(struct bpf_verifier_log *log,
+                                   const struct bpf_reg_state *reg,
+                                   int off, int size)
+{
+       if (off < 0 || off + size > sizeof(struct st_ops_args))
+               return -EACCES;
+       return 0;
+}
+
+static const struct bpf_verifier_ops st_ops_verifier_ops = {
+       .is_valid_access = bpf_testmod_ops_is_valid_access,
+       .btf_struct_access = st_ops_btf_struct_access,
+       .gen_prologue = st_ops_gen_prologue,
+       .gen_epilogue = st_ops_gen_epilogue,
+       .get_func_proto = bpf_base_func_proto,
+};
+
+static struct bpf_testmod_st_ops st_ops_cfi_stubs = {
+       .test_prologue = bpf_test_mod_st_ops__test_prologue,
+       .test_epilogue = bpf_test_mod_st_ops__test_epilogue,
+       .test_pro_epilogue = bpf_test_mod_st_ops__test_pro_epilogue,
+};
+
+static int st_ops_reg(void *kdata, struct bpf_link *link)
+{
+       int err = 0;
+
+       mutex_lock(&st_ops_mutex);
+       if (st_ops) {
+               pr_err("st_ops has already been registered\n");
+               err = -EEXIST;
+               goto unlock;
+       }
+       st_ops = kdata;
+
+unlock:
+       mutex_unlock(&st_ops_mutex);
+       return err;
+}
+
+static void st_ops_unreg(void *kdata, struct bpf_link *link)
+{
+       mutex_lock(&st_ops_mutex);
+       st_ops = NULL;
+       mutex_unlock(&st_ops_mutex);
+}
+
+static int st_ops_init(struct btf *btf)
+{
+       return 0;
+}
+
+static int st_ops_init_member(const struct btf_type *t,
+                             const struct btf_member *member,
+                             void *kdata, const void *udata)
+{
+       return 0;
+}
+
+static struct bpf_struct_ops testmod_st_ops = {
+       .verifier_ops = &st_ops_verifier_ops,
+       .init = st_ops_init,
+       .init_member = st_ops_init_member,
+       .reg = st_ops_reg,
+       .unreg = st_ops_unreg,
+       .cfi_stubs = &st_ops_cfi_stubs,
+       .name = "bpf_testmod_st_ops",
+       .owner = THIS_MODULE,
+};
+
 extern int bpf_fentry_test1(int a);
 
 static int bpf_testmod_init(void)
@@ -1117,8 +1305,10 @@ static int bpf_testmod_init(void)
        ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SCHED_CLS, &bpf_testmod_kfunc_set);
        ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_TRACING, &bpf_testmod_kfunc_set);
        ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_SYSCALL, &bpf_testmod_kfunc_set);
+       ret = ret ?: register_btf_kfunc_id_set(BPF_PROG_TYPE_STRUCT_OPS, &bpf_testmod_kfunc_set);
        ret = ret ?: register_bpf_struct_ops(&bpf_bpf_testmod_ops, bpf_testmod_ops);
        ret = ret ?: register_bpf_struct_ops(&bpf_testmod_ops2, bpf_testmod_ops2);
+       ret = ret ?: register_bpf_struct_ops(&testmod_st_ops, bpf_testmod_st_ops);
        ret = ret ?: register_btf_id_dtor_kfuncs(bpf_testmod_dtors,
                                                 ARRAY_SIZE(bpf_testmod_dtors),
                                                 THIS_MODULE);
index fe0d402b0d6531fa3113acc2ab3123ff1cdd29fa..fb7dff47597ac3b5dab58964384861609fcbe827 100644 (file)
@@ -94,4 +94,15 @@ struct bpf_testmod_ops2 {
        int (*test_1)(void);
 };
 
+struct st_ops_args {
+       u64 a;
+};
+
+struct bpf_testmod_st_ops {
+       int (*test_prologue)(struct st_ops_args *args);
+       int (*test_epilogue)(struct st_ops_args *args);
+       int (*test_pro_epilogue)(struct st_ops_args *args);
+       struct module *owner;
+};
+
 #endif /* _BPF_TESTMOD_H */
index c6c314965bb1bea2568e1ac1f6746343dfa1ca1f..7e76532be5fa40fc09455906e56280065193c2d9 100644 (file)
@@ -148,4 +148,10 @@ struct sk_buff *bpf_kfunc_nested_acquire_nonzero_offset_test(struct sk_buff_head
 struct sk_buff *bpf_kfunc_nested_acquire_zero_offset_test(struct sock_common *ptr) __ksym;
 void bpf_kfunc_nested_release_test(struct sk_buff *ptr) __ksym;
 
+struct st_ops_args;
+int bpf_kfunc_st_ops_test_prologue(struct st_ops_args *args) __ksym;
+int bpf_kfunc_st_ops_test_epilogue(struct st_ops_args *args) __ksym;
+int bpf_kfunc_st_ops_test_pro_epilogue(struct st_ops_args *args) __ksym;
+int bpf_kfunc_st_ops_inc10(struct st_ops_args *args) __ksym;
+
 #endif /* _BPF_TESTMOD_KFUNC_H */
diff --git a/tools/testing/selftests/bpf/prog_tests/pro_epilogue.c b/tools/testing/selftests/bpf/prog_tests/pro_epilogue.c
new file mode 100644 (file)
index 0000000..00b8068
--- /dev/null
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+
+#include <test_progs.h>
+#include "pro_epilogue.skel.h"
+
+void test_pro_epilogue(void)
+{
+       RUN_TESTS(pro_epilogue);
+}
diff --git a/tools/testing/selftests/bpf/progs/pro_epilogue.c b/tools/testing/selftests/bpf/progs/pro_epilogue.c
new file mode 100644 (file)
index 0000000..44bc3f0
--- /dev/null
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_tracing.h>
+#include "bpf_misc.h"
+#include "../bpf_testmod/bpf_testmod.h"
+#include "../bpf_testmod/bpf_testmod_kfunc.h"
+
+char _license[] SEC("license") = "GPL";
+
+void __kfunc_btf_root(void)
+{
+       bpf_kfunc_st_ops_inc10(NULL);
+}
+
+static __noinline __used int subprog(struct st_ops_args *args)
+{
+       args->a += 1;
+       return args->a;
+}
+
+__success
+/* prologue */
+__xlated("0: r6 = *(u64 *)(r1 +0)")
+__xlated("1: r7 = *(u64 *)(r6 +0)")
+__xlated("2: r7 += 1000")
+__xlated("3: *(u64 *)(r6 +0) = r7")
+/* main prog */
+__xlated("4: r1 = *(u64 *)(r1 +0)")
+__xlated("5: r6 = r1")
+__xlated("6: call kernel-function")
+__xlated("7: r1 = r6")
+__xlated("8: call pc+1")
+__xlated("9: exit")
+SEC("struct_ops/test_prologue")
+__naked int test_prologue(void)
+{
+       asm volatile (
+       "r1 = *(u64 *)(r1 +0);"
+       "r6 = r1;"
+       "call %[bpf_kfunc_st_ops_inc10];"
+       "r1 = r6;"
+       "call subprog;"
+       "exit;"
+       :
+       : __imm(bpf_kfunc_st_ops_inc10)
+       : __clobber_all);
+}
+
+__success
+/* save __u64 *ctx to stack */
+__xlated("0: *(u64 *)(r10 -8) = r1")
+/* main prog */
+__xlated("1: r1 = *(u64 *)(r1 +0)")
+__xlated("2: r6 = r1")
+__xlated("3: call kernel-function")
+__xlated("4: r1 = r6")
+__xlated("5: call pc+")
+/* epilogue */
+__xlated("6: r1 = *(u64 *)(r10 -8)")
+__xlated("7: r1 = *(u64 *)(r1 +0)")
+__xlated("8: r6 = *(u64 *)(r1 +0)")
+__xlated("9: r6 += 10000")
+__xlated("10: *(u64 *)(r1 +0) = r6")
+__xlated("11: r0 = r6")
+__xlated("12: r0 *= 2")
+__xlated("13: exit")
+SEC("struct_ops/test_epilogue")
+__naked int test_epilogue(void)
+{
+       asm volatile (
+       "r1 = *(u64 *)(r1 +0);"
+       "r6 = r1;"
+       "call %[bpf_kfunc_st_ops_inc10];"
+       "r1 = r6;"
+       "call subprog;"
+       "exit;"
+       :
+       : __imm(bpf_kfunc_st_ops_inc10)
+       : __clobber_all);
+}
+
+__success
+/* prologue */
+__xlated("0: r6 = *(u64 *)(r1 +0)")
+__xlated("1: r7 = *(u64 *)(r6 +0)")
+__xlated("2: r7 += 1000")
+__xlated("3: *(u64 *)(r6 +0) = r7")
+/* save __u64 *ctx to stack */
+__xlated("4: *(u64 *)(r10 -8) = r1")
+/* main prog */
+__xlated("5: r1 = *(u64 *)(r1 +0)")
+__xlated("6: r6 = r1")
+__xlated("7: call kernel-function")
+__xlated("8: r1 = r6")
+__xlated("9: call pc+")
+/* epilogue */
+__xlated("10: r1 = *(u64 *)(r10 -8)")
+__xlated("11: r1 = *(u64 *)(r1 +0)")
+__xlated("12: r6 = *(u64 *)(r1 +0)")
+__xlated("13: r6 += 10000")
+__xlated("14: *(u64 *)(r1 +0) = r6")
+__xlated("15: r0 = r6")
+__xlated("16: r0 *= 2")
+__xlated("17: exit")
+SEC("struct_ops/test_pro_epilogue")
+__naked int test_pro_epilogue(void)
+{
+       asm volatile (
+       "r1 = *(u64 *)(r1 +0);"
+       "r6 = r1;"
+       "call %[bpf_kfunc_st_ops_inc10];"
+       "r1 = r6;"
+       "call subprog;"
+       "exit;"
+       :
+       : __imm(bpf_kfunc_st_ops_inc10)
+       : __clobber_all);
+}
+
+SEC("syscall")
+__retval(1011) /* PROLOGUE_A [1000] + KFUNC_INC10 + SUBPROG_A [1] */
+int syscall_prologue(void *ctx)
+{
+       struct st_ops_args args = {};
+
+       return bpf_kfunc_st_ops_test_prologue(&args);
+}
+
+SEC("syscall")
+__retval(20022) /* (KFUNC_INC10 + SUBPROG_A [1] + EPILOGUE_A [10000]) * 2 */
+int syscall_epilogue(void *ctx)
+{
+       struct st_ops_args args = {};
+
+       return bpf_kfunc_st_ops_test_epilogue(&args);
+}
+
+SEC("syscall")
+__retval(22022) /* (PROLOGUE_A [1000] + KFUNC_INC10 + SUBPROG_A [1] + EPILOGUE_A [10000]) * 2 */
+int syscall_pro_epilogue(void *ctx)
+{
+       struct st_ops_args args = {};
+
+       return bpf_kfunc_st_ops_test_pro_epilogue(&args);
+}
+
+SEC(".struct_ops.link")
+struct bpf_testmod_st_ops pro_epilogue = {
+       .test_prologue = (void *)test_prologue,
+       .test_epilogue = (void *)test_epilogue,
+       .test_pro_epilogue = (void *)test_pro_epilogue,
+};