Hi Teo,
On Tue, Nov 15, 2022 at 05:01:06PM +0000, Teo Couprie Diaz wrote:
Direct usage of brk is discouraged in favor of using malloc. Also, brk was removed from POSIX in POSIX.1-2001. In particular, the musl libc's brk always returns -ENOMEM which causes the LTP tests to fail. Invoking the syscall directly allows them to pass.
How about: ... which causes the LTP tests to fail prematurely. Invoking the syscall directly allows them to carry out their validation of brk behaviour. ?
Instead, use tst_syscall() and handle the failure cases ourselves, as we don't depend on the libc to do it anymore.
The patch also removes the dependency on sbrk to get the current break as it has the same issues. Instead, call tst_syscall(__NR_brk, 0) which should always fail, returning the current break.
Signed-off-by: Teo Couprie Diaz teo.coupriediaz@arm.com
I believe this patch could be upstreamed, maybe at first as an RFC to gather interest, as it would fix the tests for Musl distributions.
testcases/kernel/syscalls/brk/brk01.c | 9 +++------ testcases/kernel/syscalls/brk/brk02.c | 14 ++++++-------- 2 files changed, 9 insertions(+), 14 deletions(-)
diff --git a/testcases/kernel/syscalls/brk/brk01.c b/testcases/kernel/syscalls/brk/brk01.c index 5f482b943..919435755 100644 --- a/testcases/kernel/syscalls/brk/brk01.c +++ b/testcases/kernel/syscalls/brk/brk01.c @@ -9,6 +9,7 @@ #include <errno.h> #include "tst_test.h" +#include "lapi/syscalls.h" void verify_brk(void) { @@ -16,7 +17,7 @@ void verify_brk(void) size_t inc = getpagesize() * 2 - 1; unsigned int i;
- cur_brk = (uintptr_t)sbrk(0);
- cur_brk = (uintptr_t)tst_syscall(__NR_brk, 0);
for (i = 0; i < 33; i++) { switch (i % 3) { @@ -31,11 +32,7 @@ void verify_brk(void) break; }
TST_EXP_PASS_SILENT(brk((void *)new_brk), "brk()");if (!TST_PASS)return;cur_brk = (uintptr_t)sbrk(0);
cur_brk = tst_syscall(__NR_brk, new_brk);
For consistency it would be good to add explicit cast here (as already mentioned by Tudor). On the other hand, the explicit cast is no longer necessary as tst_syscall is dealing with intptr_t already, so you gonna get implicit conversion here either way.
--- BR B.
if (cur_brk != new_brk) { tst_res(TFAIL, diff --git a/testcases/kernel/syscalls/brk/brk02.c b/testcases/kernel/syscalls/brk/brk02.c index 11e803cb4..dabda30c2 100644 --- a/testcases/kernel/syscalls/brk/brk02.c +++ b/testcases/kernel/syscalls/brk/brk02.c @@ -14,24 +14,22 @@ #include <unistd.h> #include <sys/mman.h> #include "tst_test.h" +#include "lapi/syscalls.h" void brk_down_vmas(void) {
- void *brk_addr = sbrk(0);
- if (brk_addr == (void *) -1)
tst_brk(TBROK, "sbrk() failed");
- void *brk_addr = (void *)tst_syscall(__NR_brk, 0);
unsigned long page_size = getpagesize(); void *addr = brk_addr + page_size;
- if (brk(addr)) {
- if ((void *)tst_syscall(__NR_brk, addr) < addr) { tst_res(TFAIL | TERRNO, "Cannot expand brk() by page size"); return; }
addr += page_size;
- if (brk(addr)) {
- if ((void *)tst_syscall(__NR_brk, addr) < addr) { tst_res(TFAIL | TERRNO, "Cannot expand brk() by 2x page size"); return; }
@@ -42,12 +40,12 @@ void brk_down_vmas(void) } addr += page_size;
- if (brk(addr)) {
- if ((void *)tst_syscall(__NR_brk, addr) < addr) { tst_res(TFAIL | TERRNO, "Cannot expand brk() after mprotect"); return; }
- if (brk(brk_addr)) {
- if ((void *)tst_syscall(__NR_brk, brk_addr) != brk_addr) { tst_res(TFAIL | TERRNO, "Cannot restore brk() to start address"); return; }
-- 2.25.1
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