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selftests: bpf: modify urandom_read and link it non-statically 

After some experiences I found that urandom_read does not need to be
linked statically. When the 'read' syscall call is moved to separate
non-inlined function then bpf_get_stackid() is able to find
the executable in stack trace and extract its build_id from it.

Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Ivan Vecera 2019-03-15 21:04:14 +01:00 committed by Alexei Starovoitov
parent ab99e7a8f7
commit f682752627
2 changed files with 12 additions and 5 deletions
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2
tools/testing/selftests/bpf/Makefile
View File

@ -70,7 +70,7 @@ TEST_CUSTOM_PROGS = $(OUTPUT)/urandom_read
all: $(TEST_CUSTOM_PROGS)
$(OUTPUT)/urandom_read: $(OUTPUT)/%: %.c
$(CC) -o $@ -static $< -Wl,--build-id
$(CC) -o $@ $< -Wl,--build-id
BPFOBJ := $(OUTPUT)/libbpf.a

15
tools/testing/selftests/bpf/urandom_read.c
View File

@ -7,11 +7,19 @@
#define BUF_SIZE 256
static __attribute__((noinline))
void urandom_read(int fd, int count)
{
char buf[BUF_SIZE];
int i;
for (i = 0; i < count; ++i)
read(fd, buf, BUF_SIZE);
}
int main(int argc, char *argv[])
{
int fd = open("/dev/urandom", O_RDONLY);
int i;
char buf[BUF_SIZE];
int count = 4;
if (fd < 0)
@ -20,8 +28,7 @@ int main(int argc, char *argv[])
if (argc == 2)
count = atoi(argv[1]);
for (i = 0; i < count; ++i)
read(fd, buf, BUF_SIZE);
urandom_read(fd, count);
close(fd);
return 0;