On 05/09/2023 16:12, Hengqi Chen wrote:
> This exercises the newly added dynsym symbol versioning logics.
> Now we accept symbols in form of func, func@LIB_VERSION or
> func@@LIB_VERSION.
>
> The test rely on liburandom_read.so. For liburandom_read.so, we have:
>
> $ nm -D liburandom_read.so
> w __cxa_finalize@GLIBC_2.17
> w __gmon_start__
> w _ITM_deregisterTMCloneTable
> w _ITM_registerTMCloneTable
> 0000000000000000 A LIBURANDOM_READ_1.0.0
> 0000000000000000 A LIBURANDOM_READ_2.0.0
> 000000000000081c T urandlib_api@@LIBURANDOM_READ_2.0.0
> 0000000000000814 T urandlib_api@LIBURANDOM_READ_1.0.0
> 0000000000000824 T urandlib_api_sameoffset@LIBURANDOM_READ_1.0.0
> 0000000000000824 T urandlib_api_sameoffset@@LIBURANDOM_READ_2.0.0
> 000000000000082c T urandlib_read_without_sema@@LIBURANDOM_READ_1.0.0
> 00000000000007c4 T urandlib_read_with_sema@@LIBURANDOM_READ_1.0.0
> 0000000000011018 D urandlib_read_with_sema_semaphore@@LIBURANDOM_READ_1.0.0
>
> For `urandlib_api`, specifying `urandlib_api` will cause a conflict because
> there are two symbols named urandlib_api and both are global bind.
> For `urandlib_api_sameoffset`, there are also two symbols in the .so, but
> both are at the same offset and essentially they refer to the same function
> so no conflict.
>
> Signed-off-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>
Great work putting tests together for this! One small suggestion if
there's a v3; would it be worth having a uretprobe test that uses
library version specification too?
Reviewed-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
> tools/testing/selftests/bpf/Makefile | 5 +-
> .../testing/selftests/bpf/liburandom_read.map | 15 +++
> .../testing/selftests/bpf/prog_tests/uprobe.c | 95 +++++++++++++++++++
> .../testing/selftests/bpf/progs/test_uprobe.c | 61 ++++++++++++
> tools/testing/selftests/bpf/urandom_read.c | 9 ++
> .../testing/selftests/bpf/urandom_read_lib1.c | 41 ++++++++
> 6 files changed, 224 insertions(+), 2 deletions(-)
> create mode 100644 tools/testing/selftests/bpf/liburandom_read.map
> create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe.c
> create mode 100644 tools/testing/selftests/bpf/progs/test_uprobe.c
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index edef49fcd23e..49ff9c716b79 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -193,11 +193,12 @@ endif
>
> # Filter out -static for liburandom_read.so and its dependent targets so that static builds
> # do not fail. Static builds leave urandom_read relying on system-wide shared libraries.
> -$(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c
> +$(OUTPUT)/liburandom_read.so: urandom_read_lib1.c urandom_read_lib2.c liburandom_read.map
> $(call msg,LIB,,$@)
> $(Q)$(CLANG) $(filter-out -static,$(CFLAGS) $(LDFLAGS)) \
> - $^ $(filter-out -static,$(LDLIBS)) \
> + $(filter %.c,$^) $(filter-out -static,$(LDLIBS)) \
> -fuse-ld=$(LLD) -Wl,-znoseparate-code -Wl,--build-id=sha1 \
> + -Wl,--version-script=liburandom_read.map \
> -fPIC -shared -o $@
>
> $(OUTPUT)/urandom_read: urandom_read.c urandom_read_aux.c $(OUTPUT)/liburandom_read.so
> diff --git a/tools/testing/selftests/bpf/liburandom_read.map b/tools/testing/selftests/bpf/liburandom_read.map
> new file mode 100644
> index 000000000000..38a97a419a04
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/liburandom_read.map
> @@ -0,0 +1,15 @@
> +LIBURANDOM_READ_1.0.0 {
> + global:
> + urandlib_api;
> + urandlib_api_sameoffset;
> + urandlib_read_without_sema;
> + urandlib_read_with_sema;
> + urandlib_read_with_sema_semaphore;
> + local:
> + *;
> +};
> +
> +LIBURANDOM_READ_2.0.0 {
> + global:
> + urandlib_api;
> +} LIBURANDOM_READ_1.0.0;
> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe.c b/tools/testing/selftests/bpf/prog_tests/uprobe.c
> new file mode 100644
> index 000000000000..6c619bcca41c
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe.c
> @@ -0,0 +1,95 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2021 Hengqi Chen */
> +
> +#include <test_progs.h>
> +#include "test_uprobe.skel.h"
> +
> +static FILE *urand_spawn(int *pid)
> +{
> + FILE *f;
> +
> + /* urandom_read's stdout is wired into f */
> + f = popen("./urandom_read 1 report-pid", "r");
> + if (!f)
> + return NULL;
> +
> + if (fscanf(f, "%d", pid) != 1) {
> + pclose(f);
> + errno = EINVAL;
> + return NULL;
> + }
> +
> + return f;
> +}
> +
> +static int urand_trigger(FILE **urand_pipe)
> +{
> + int exit_code;
> +
> + /* pclose() waits for child process to exit and returns their exit code */
> + exit_code = pclose(*urand_pipe);
> + *urand_pipe = NULL;
> +
> + return exit_code;
> +}
> +
> +void test_uprobe(void)
> +{
> + LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
> + struct test_uprobe *skel;
> + FILE *urand_pipe = NULL;
> + int urand_pid = 0, err;
> +
> + skel = test_uprobe__open_and_load();
> + if (!ASSERT_OK_PTR(skel, "skel_open"))
> + return;
> +
> + urand_pipe = urand_spawn(&urand_pid);
> + if (!ASSERT_OK_PTR(urand_pipe, "urand_spawn"))
> + goto cleanup;
> +
> + skel->bss->my_pid = urand_pid;
> +
> + /* Manual attach uprobe to urandlib_api
> + * There are two `urandlib_api` symbols in .dynsym section:
> + * - urandlib_api@LIBURANDOM_READ_1.0.0
> + * - urandlib_api@LIBURANDOM_READ_1.0.0
> + * Both are global bind and would cause a conflict if user
> + * specify the symbol name without a version suffix
> + */
> + uprobe_opts.func_name = "urandlib_api";
> + skel->links.test4 = bpf_program__attach_uprobe_opts(skel->progs.test4,
> + urand_pid,
> + "./liburandom_read.so",
> + 0 /* offset */,
> + &uprobe_opts);
> + if (!ASSERT_ERR_PTR(skel->links.test4, "urandlib_api_attach_conflict"))
> + goto cleanup;
> +
> + uprobe_opts.func_name = "urandlib_api@LIBURANDOM_READ_1.0.0";
> + skel->links.test4 = bpf_program__attach_uprobe_opts(skel->progs.test4,
> + urand_pid,
> + "./liburandom_read.so",
> + 0 /* offset */,
> + &uprobe_opts);
> + if (!ASSERT_OK_PTR(skel->links.test4, "urandlib_api_attach_ok"))
> + goto cleanup;
> +
> + /* Auto attach 3 uprobes to urandlib_api_sameoffset */
> + err = test_uprobe__attach(skel);
> + if (!ASSERT_OK(err, "skel_attach"))
> + goto cleanup;
> +
> + /* trigger urandom_read */
> + ASSERT_OK(urand_trigger(&urand_pipe), "urand_exit_code");
> +
> + ASSERT_EQ(skel->bss->test1_result, 1, "urandlib_api_sameoffset");
> + ASSERT_EQ(skel->bss->test2_result, 1, "urandlib_api_sameoffset@v1");
> + ASSERT_EQ(skel->bss->test3_result, 1, "urandlib_api_sameoffset@@v2");
> + ASSERT_EQ(skel->bss->test4_result, 1, "urandlib_api");
> +
> +cleanup:
> + if (urand_pipe)
> + pclose(urand_pipe);
> + test_uprobe__destroy(skel);
> +}
> diff --git a/tools/testing/selftests/bpf/progs/test_uprobe.c b/tools/testing/selftests/bpf/progs/test_uprobe.c
> new file mode 100644
> index 000000000000..8680280558da
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_uprobe.c
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Copyright (c) 2023 Hengqi Chen */
> +
> +#include "vmlinux.h"
> +#include <bpf/bpf_helpers.h>
> +#include <bpf/bpf_tracing.h>
> +
> +pid_t my_pid = 0;
> +
> +int test1_result = 0;
> +int test2_result = 0;
> +int test3_result = 0;
> +int test4_result = 0;
> +
> +SEC("uprobe/./liburandom_read.so:urandlib_api_sameoffset")
> +int BPF_UPROBE(test1)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + test1_result = 1;
> + return 0;
> +}
> +
> +SEC("uprobe/./liburandom_read.so:urandlib_api_sameoffset@LIBURANDOM_READ_1.0.0")
> +int BPF_UPROBE(test2)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + test2_result = 1;
> + return 0;
> +}
> +
> +SEC("uprobe/./liburandom_read.so:urandlib_api_sameoffset@@LIBURANDOM_READ_2.0.0")
> +int BPF_UPROBE(test3)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + test3_result = 1;
> + return 0;
> +}
> +
> +SEC("uprobe")
> +int BPF_UPROBE(test4)
> +{
> + pid_t pid = bpf_get_current_pid_tgid() >> 32;
> +
> + if (pid != my_pid)
> + return 0;
> +
> + test4_result = 1;
> + return 0;
> +}
> diff --git a/tools/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c
> index e92644d0fa75..b28e910a8fbb 100644
> --- a/tools/testing/selftests/bpf/urandom_read.c
> +++ b/tools/testing/selftests/bpf/urandom_read.c
> @@ -21,6 +21,11 @@ void urand_read_without_sema(int iter_num, int iter_cnt, int read_sz);
> void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz);
> void urandlib_read_without_sema(int iter_num, int iter_cnt, int read_sz);
>
> +int urandlib_api(void);
> +__asm__(".symver urandlib_api_old,urandlib_api@LIBURANDOM_READ_1.0.0");
> +int urandlib_api_old(void);
> +int urandlib_api_sameoffset(void);
> +
> unsigned short urand_read_with_sema_semaphore SEC(".probes");
>
> static __attribute__((noinline))
> @@ -83,6 +88,10 @@ int main(int argc, char *argv[])
>
> urandom_read(fd, count);
>
> + urandlib_api();
> + urandlib_api_old();
> + urandlib_api_sameoffset();
> +
> close(fd);
> return 0;
> }
> diff --git a/tools/testing/selftests/bpf/urandom_read_lib1.c b/tools/testing/selftests/bpf/urandom_read_lib1.c
> index 86186e24b740..403b0735e223 100644
> --- a/tools/testing/selftests/bpf/urandom_read_lib1.c
> +++ b/tools/testing/selftests/bpf/urandom_read_lib1.c
> @@ -11,3 +11,44 @@ void urandlib_read_with_sema(int iter_num, int iter_cnt, int read_sz)
> {
> STAP_PROBE3(urandlib, read_with_sema, iter_num, iter_cnt, read_sz);
> }
> +
> +/* Symbol versioning is different between static and shared library.
> + * Properly versioned symbols are needed for shared library, but
> + * only the symbol of the new version is needed for static library.
> + * Starting with GNU C 10, use symver attribute instead of .symver assembler
> + * directive, which works better with GCC LTO builds.
> + */
> +#if defined(__GNUC__) && __GNUC__ >= 10
> +
> +#define DEFAULT_VERSION(internal_name, api_name, version) \
> + __attribute__((symver(#api_name "@@" #version)))
> +#define COMPAT_VERSION(internal_name, api_name, version) \
> + __attribute__((symver(#api_name "@" #version)))
> +
> +#else
> +
> +#define COMPAT_VERSION(internal_name, api_name, version) \
> + asm(".symver " #internal_name "," #api_name "@" #version);
> +#define DEFAULT_VERSION(internal_name, api_name, version) \
> + asm(".symver " #internal_name "," #api_name "@@" #version);
> +
> +#endif
> +
> +COMPAT_VERSION(urandlib_api_v1, urandlib_api, LIBURANDOM_READ_1.0.0)
> +int urandlib_api_v1(void)
> +{
> + return 1;
> +}
> +
> +DEFAULT_VERSION(urandlib_api_v2, urandlib_api, LIBURANDOM_READ_2.0.0)
> +int urandlib_api_v2(void)
> +{
> + return 2;
> +}
> +
> +COMPAT_VERSION(urandlib_api_sameoffset, urandlib_api_sameoffset, LIBURANDOM_READ_1.0.0)
> +DEFAULT_VERSION(urandlib_api_sameoffset, urandlib_api_sameoffset, LIBURANDOM_READ_2.0.0)
> +int urandlib_api_sameoffset(void)
> +{
> + return 3;
> +}
> --
> 2.34.1
