[PATCH bpf-next v3 0/5] selftests/bpf: libarena cleanup and bitmap struct

[PATCH bpf-next v3 0/5] selftests/bpf: libarena cleanup and bitmap struct

[Emil Tsalapatis]

Cleanup patches for libarena, along with a new bitmap data type that is
in use by sched-ext. Patch 1 is an NFC that properly renames the buddy
selftests for consistency. Patch 2 fixes the zero variable used in
libarena for can_loop based looping, and afterwrds removes all bpf_for()
instances from the code. Patch 3 fixes an (untriggered) edge case that 
could cause spurious selftest failures. Finally, patches 4 and 5
introduce the bitmap data structure along with selftests.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>


CHANGELOG
=========

v2 -> v3: (https://lore.kernel.org/bpf/20260701185235.4516-1-emil@etsalapatis.com)
- Remove unused macros and fix typo in commit message (AI)

v1 -> v2: (https://lore.kernel.org/bpf/20260618085626.19633-1-emil@etsalapatis.com)

- Added acks by Ihor and Eduard
- Fix missing commit message (Ihor)
- Enforce 64 bits per cell with BITS_TO_LONG_LONG (Sashiko)
- Add test for bmp_copy (Ihor)
- Add atomic versions of _set() and _clear() (Ihor) and add a parallel
  selftest for them.



Emil Tsalapatis (5):
  selftests/bpf: libarena: Fix can-loop zero variable definition
  selftests/bpf: libarena: Clean up allocation state before buddy tests
  selftests/bpf: Add arena-based bitmap data structure
  selftests/bpf: libarena: Add bitmap selftests
  selftests/bpf: libarena: Add parallel bitmap selftest

 .../bpf/libarena/include/libarena/bitmap.h    |  34 ++
 .../bpf/libarena/include/libarena/common.h    |   2 +-
 .../libarena/selftests/test_asan_buddy.bpf.c  |   8 +-
 .../bpf/libarena/selftests/test_bitmap.bpf.c  | 394 ++++++++++++++++++
 .../bpf/libarena/selftests/test_buddy.bpf.c   |   8 +-
 .../selftests/test_parallel_bitmap.bpf.c      | 190 +++++++++
 .../selftests/test_parallel_spmc.bpf.c        |   9 +-
 .../selftests/bpf/libarena/src/bitmap.bpf.c   | 245 +++++++++++
 .../selftests/bpf/libarena/src/common.bpf.c   |   9 +-
 .../selftests/bpf/prog_tests/libarena.c       |   8 +-
 .../selftests/bpf/prog_tests/libarena_asan.c  |   8 +-
 11 files changed, 899 insertions(+), 16 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/libarena/include/libarena/bitmap.h
 create mode 100644 tools/testing/selftests/bpf/libarena/selftests/test_bitmap.bpf.c
 create mode 100644 tools/testing/selftests/bpf/libarena/selftests/test_parallel_bitmap.bpf.c
 create mode 100644 tools/testing/selftests/bpf/libarena/src/bitmap.bpf.c

-- 
2.54.0

[PATCH bpf-next v3 1/5] selftests/bpf: libarena: Fix can-loop zero variable definition

[Emil Tsalapatis]

BPF can_loop based loops require the index variable to stay imprecise.
This means we must initialize them from a currently imprecise variable
instead of directly assigning 0 to them, like so:

static volatile u32 zero = 0;

for (i = zero; i < NUM_LOOPS; i++) {
	/* loop body */
}

The libarena implementation of this technique is currently faulty. For
the technique to work, the variable must not be in a map. This includes
the .rodata DATASEC map used for const variables. However, libarena
still defines the zero variable as constant.

Modify the zero variable definition into a volatile variable. This
change adds a complication caused by the compiler optimizing array
derefences from

for (i = zero; i < NUM_LOOPS; i++) {
	val = *(ptr + i);
}

into

for (i = zero; i < NUM_LOOPS; i++) {
	val = *ptr++;
}

and causing verification failures. Use the barrier_var() clobber macro
to prevent this optimization from taking place. Using barrier_var() is
the only way to break the optimization, as annotating the index as
volatile does not suffice.

After that, remove the bpf_for() invocations introduced in libarena for
parallel spmc testing.

Reported-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../selftests/bpf/libarena/include/libarena/common.h     | 2 +-
 .../bpf/libarena/selftests/test_asan_buddy.bpf.c         | 8 ++++++--
 .../selftests/bpf/libarena/selftests/test_buddy.bpf.c    | 8 ++++++--
 .../bpf/libarena/selftests/test_parallel_spmc.bpf.c      | 9 ++++-----
 tools/testing/selftests/bpf/libarena/src/common.bpf.c    | 3 +--
 5 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/common.h b/tools/testing/selftests/bpf/libarena/include/libarena/common.h
index a3eb1641ac36..931ace9a49e2 100644
--- a/tools/testing/selftests/bpf/libarena/include/libarena/common.h
+++ b/tools/testing/selftests/bpf/libarena/include/libarena/common.h
@@ -43,7 +43,7 @@ struct {
  * imprecise. To force the variable to be imprecise, initialize it with
  * the opaque volatile variable 0 instead of the constant 0.
  */
-extern const volatile u32 zero;
+volatile u32 zero __weak;
 extern volatile u64 asan_violated;
 
 int arena_fls(__u64 word);
diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_asan_buddy.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_asan_buddy.bpf.c
index 256d62a03ce7..3266a28f53d7 100644
--- a/tools/testing/selftests/bpf/libarena/selftests/test_asan_buddy.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/selftests/test_asan_buddy.bpf.c
@@ -154,7 +154,8 @@ __weak int asan_test_buddy_oob(void)
 	size_t sizes[] = {
 		7, 8, 17, 18, 64, 256, 317, 512, 1024,
 	};
-	int ret, i;
+	int ret;
+	u32 i;
 
 	ret = buddy_init(&buddy);
 	if (ret) {
@@ -163,6 +164,7 @@ __weak int asan_test_buddy_oob(void)
 	}
 
 	for (i = zero; i < sizeof(sizes) / sizeof(sizes[0]) && can_loop; i++) {
+		barrier_var(i);
 		ret = asan_test_buddy_oob_single(sizes[i]);
 		if (ret) {
 			arena_stdout("%s:%d Failed for size %lu", __func__,
@@ -190,7 +192,8 @@ __stderr("Call trace:\n"
 __weak int asan_test_buddy_uaf(void)
 {
 	size_t sizes[] = { 16, 32, 64, 128, 256, 512, 1024, 16384 };
-	int ret, i;
+	int ret;
+	u32 i;
 
 	ret = buddy_init(&buddy);
 	if (ret) {
@@ -199,6 +202,7 @@ __weak int asan_test_buddy_uaf(void)
 	}
 
 	for (i = zero; i < sizeof(sizes) / sizeof(sizes[0]) && can_loop; i++) {
+		barrier_var(i);
 		ret = asan_test_buddy_uaf_single(sizes[i]);
 		if (ret) {
 			arena_stdout("%s:%d Failed for size %lu", __func__,
diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_buddy.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_buddy.bpf.c
index b45a306816c0..5628f0987012 100644
--- a/tools/testing/selftests/bpf/libarena/selftests/test_buddy.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/selftests/test_buddy.bpf.c
@@ -171,7 +171,8 @@ __weak int test_buddy_alloc_multiple(void)
 SEC("syscall")
 __weak int test_buddy_alignment(void)
 {
-	int ret, i;
+	int ret;
+	u32 i;
 
 	ret = buddy_init(&buddy);
 	if (ret)
@@ -179,6 +180,7 @@ __weak int test_buddy_alignment(void)
 
 	/* Allocate various sizes and check alignment */
 	for (i = zero; i < 17 && can_loop; i++) {
+		barrier_var(i);
 		ptrs[i] = buddy_alloc(&buddy, alignment_sizes[i]);
 		if (!ptrs[i]) {
 			arena_stdout("alignment test: alloc failed for size %lu",
@@ -198,8 +200,10 @@ __weak int test_buddy_alignment(void)
 	}
 
 	/* Free all allocations */
-	for (i = zero; i < 17 && can_loop; i++)
+	for (i = zero; i < 17 && can_loop; i++) {
+		barrier_var(i);
 		buddy_free(&buddy, ptrs[i]);
+	}
 
 	buddy_destroy(&buddy);
 
diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c
index f08f2a92e194..5fa96eb74095 100644
--- a/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_spmc.bpf.c
@@ -155,7 +155,7 @@ int spmc_quiesce_on_owner(u64 epoch)
 {
 	u64 i;
 
-	bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) {
+	for (i = zero; i < TEST_SPMC_SYNC_SPINS && can_loop; i++) {
 		if (test_abort)
 			return -EINTR;
 		if (smp_load_acquire(&owner_epoch) >= epoch)
@@ -175,8 +175,7 @@ int spmc_quiesce_on_stealer(u64 epoch)
 	int err = -ETIMEDOUT;
 
 	target = STEALER_EPOCH(epoch);
-	bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) {
-
+	for (i = zero; i < TEST_SPMC_SYNC_SPINS && can_loop; i++) {
 		if (test_abort) {
 			err = -EINTR;
 			break;
@@ -391,7 +390,7 @@ int spmc_wait_for_stealers_to_start(u64 target)
 {
 	u64 i;
 
-	bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) {
+	for (i = zero; i < TEST_SPMC_SYNC_SPINS && can_loop; i++) {
 		if (test_abort)
 			return -EINTR;
 		if (READ_ONCE(stealers_started) >= target)
@@ -537,7 +536,7 @@ static int spmc_wait_for_round_steals(u64 target)
 
 	arena_subprog_init();
 
-	bpf_for(i, 0, TEST_SPMC_SYNC_SPINS) {
+	for (i = zero; i < TEST_SPMC_SYNC_SPINS && can_loop; i++) {
 		if (test_abort)
 			return -EINTR;
 		if (round_steals >= target)
diff --git a/tools/testing/selftests/bpf/libarena/src/common.bpf.c b/tools/testing/selftests/bpf/libarena/src/common.bpf.c
index 50be57213dfb..1b4bb19b3c52 100644
--- a/tools/testing/selftests/bpf/libarena/src/common.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/src/common.bpf.c
@@ -4,9 +4,8 @@
 #include <libarena/asan.h>
 #include <libarena/buddy.h>
 
-const volatile u32 zero = 0;
-
 struct buddy __arena buddy;
+volatile u32 zero = 0;
 
 int arena_fls(__u64 word)
 {
-- 
2.54.0

Re: [PATCH bpf-next v3 1/5] selftests/bpf: libarena: Fix can-loop zero variable definition

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 2368 bytes --]

>     selftests/bpf: libarena: Fix can-loop zero variable definition
>
>     BPF can_loop based loops require the index variable to stay imprecise.
>     This means we must initialize them from a currently imprecise variable
>     instead of directly assigning 0 to them, like so:
>
>     static volatile u32 zero = 0;
>
>     for (i = zero; i < NUM_LOOPS; i++) {
>             /* loop body */
>     }
>
>     The libarena implementation of this technique is currently faulty. For
>     the technique to work, the variable must not be in a map. This includes
>     the .rodata DATASEC map used for const variables. However, libarena
>     still defines the zero variable as constant.
>
>     Modify the zero variable definition into a volatile variable. This
>     change adds a complication caused by the compiler optimizing array
>     derefences from
>
>     for (i = zero; i < NUM_LOOPS; i++) {
>             val = *(ptr + i);
>     }
>
>     into
>
>     for (i = zero; i < NUM_LOOPS; i++) {
>             val = *ptr++;
>     }
>
>     and causing verification failures. Use the barrier_var() clobber macro
>     to prevent this optimization from taking place. Using barrier_var() is
>     the only way to break the optimization, as annotating the index as
>     volatile does not suffice.
>
>     After that, remove the bpf_for() invocations introduced in libarena for
>     parallel spmc testing.
>
>     Reported-by: Eduard Zingerman <eddyz87@gmail.com>
>     Acked-by: Eduard Zingerman <eddyz87@gmail.com>
>     Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>

This corrects a bug where the "zero" variable was defined as
"const volatile u32 zero = 0;" in src/common.bpf.c and declared as
"extern const volatile u32 zero;" in include/libarena/common.h.  Being
const placed it in the .rodata DATASEC map, which defeats the
imprecise-index technique that can_loop loops rely on.  Both the faulty
definition and declaration were added by commit d5327480a12a
("selftests/bpf: Add basic libarena scaffolding").

Should this carry a Fixes: tag?

  Fixes: d5327480a12a ("selftests/bpf: Add basic libarena scaffolding")


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/28553504082

Re: [PATCH bpf-next v3 1/5] selftests/bpf: libarena: Fix can-loop zero variable definition

[Kumar Kartikeya Dwivedi]

On Thu Jul 2, 2026 at 12:50 AM CEST, Emil Tsalapatis wrote:
> BPF can_loop based loops require the index variable to stay imprecise.
> This means we must initialize them from a currently imprecise variable
> instead of directly assigning 0 to them, like so:
>
> static volatile u32 zero = 0;
>
> for (i = zero; i < NUM_LOOPS; i++) {
> 	/* loop body */
> }
>
> The libarena implementation of this technique is currently faulty. For
> the technique to work, the variable must not be in a map. This includes
> the .rodata DATASEC map used for const variables. However, libarena
> still defines the zero variable as constant.
>
> Modify the zero variable definition into a volatile variable. This
> change adds a complication caused by the compiler optimizing array
> derefences from
>
> for (i = zero; i < NUM_LOOPS; i++) {
> 	val = *(ptr + i);
> }
>
> into
>
> for (i = zero; i < NUM_LOOPS; i++) {
> 	val = *ptr++;
> }
>
> and causing verification failures. Use the barrier_var() clobber macro
> to prevent this optimization from taking place. Using barrier_var() is
> the only way to break the optimization, as annotating the index as
> volatile does not suffice.
>
> After that, remove the bpf_for() invocations introduced in libarena for
> parallel spmc testing.
>
> Reported-by: Eduard Zingerman <eddyz87@gmail.com>
> Acked-by: Eduard Zingerman <eddyz87@gmail.com>
> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
> ---
>  .../selftests/bpf/libarena/include/libarena/common.h     | 2 +-
>  .../bpf/libarena/selftests/test_asan_buddy.bpf.c         | 8 ++++++-

No such file exists, did you forget to send the renaming patch from
st_asan_buddy to test_asan_buddy ordered before this one?

Please respin. Looks good otherwise.

pw-bot: cr

Re: [PATCH bpf-next v3 1/5] selftests/bpf: libarena: Fix can-loop zero variable definition

[Emil Tsalapatis]

On Sun Jul 5, 2026 at 2:34 AM EDT, Kumar Kartikeya Dwivedi wrote:
> On Thu Jul 2, 2026 at 12:50 AM CEST, Emil Tsalapatis wrote:
>> BPF can_loop based loops require the index variable to stay imprecise.
>> This means we must initialize them from a currently imprecise variable
>> instead of directly assigning 0 to them, like so:
>>
>> static volatile u32 zero = 0;
>>
>> for (i = zero; i < NUM_LOOPS; i++) {
>> 	/* loop body */
>> }
>>
>> The libarena implementation of this technique is currently faulty. For
>> the technique to work, the variable must not be in a map. This includes
>> the .rodata DATASEC map used for const variables. However, libarena
>> still defines the zero variable as constant.
>>
>> Modify the zero variable definition into a volatile variable. This
>> change adds a complication caused by the compiler optimizing array
>> derefences from
>>
>> for (i = zero; i < NUM_LOOPS; i++) {
>> 	val = *(ptr + i);
>> }
>>
>> into
>>
>> for (i = zero; i < NUM_LOOPS; i++) {
>> 	val = *ptr++;
>> }
>>
>> and causing verification failures. Use the barrier_var() clobber macro
>> to prevent this optimization from taking place. Using barrier_var() is
>> the only way to break the optimization, as annotating the index as
>> volatile does not suffice.
>>
>> After that, remove the bpf_for() invocations introduced in libarena for
>> parallel spmc testing.
>>
>> Reported-by: Eduard Zingerman <eddyz87@gmail.com>
>> Acked-by: Eduard Zingerman <eddyz87@gmail.com>
>> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
>> ---
>>  .../selftests/bpf/libarena/include/libarena/common.h     | 2 +-
>>  .../bpf/libarena/selftests/test_asan_buddy.bpf.c         | 8 ++++++-
>
> No such file exists, did you forget to send the renaming patch from
> st_asan_buddy to test_asan_buddy ordered before this one?
>
> Please respin. Looks good otherwise.

Yes patch 1 is missing from v3. Will do a resend.

>
> pw-bot: cr

[PATCH bpf-next v3 2/5] selftests/bpf: libarena: Clean up allocation state before buddy tests

[Emil Tsalapatis]

Summary: The buddy allocator requires the global BPF buddy allocator
to not be already initialized. However, the test currently merely resets
the allocator before the buddy tests instead of destroying it, and the
test worked because the buddy test happened to run first. Properly
destroy the allocator instead of resetting it.

Fixes: b1487dc1b181 ("selftests/bpf: Add selftests for libarena buddy allocator")
Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 tools/testing/selftests/bpf/libarena/src/common.bpf.c  | 6 ++++++
 tools/testing/selftests/bpf/prog_tests/libarena.c      | 8 ++++++--
 tools/testing/selftests/bpf/prog_tests/libarena_asan.c | 8 ++++++--
 3 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/libarena/src/common.bpf.c b/tools/testing/selftests/bpf/libarena/src/common.bpf.c
index 1b4bb19b3c52..569f0f64d518 100644
--- a/tools/testing/selftests/bpf/libarena/src/common.bpf.c
+++ b/tools/testing/selftests/bpf/libarena/src/common.bpf.c
@@ -37,6 +37,12 @@ __weak int arena_buddy_reset(void)
 	return buddy_init(&buddy);
 }
 
+SEC("syscall")
+__weak int arena_buddy_destroy(void)
+{
+	return buddy_destroy(&buddy);
+}
+
 __weak void __arena *arena_malloc(size_t size)
 {
 	return buddy_alloc(&buddy, size);
diff --git a/tools/testing/selftests/bpf/prog_tests/libarena.c b/tools/testing/selftests/bpf/prog_tests/libarena.c
index 61ea68dce410..ba5a5a50f7c0 100644
--- a/tools/testing/selftests/bpf/prog_tests/libarena.c
+++ b/tools/testing/selftests/bpf/prog_tests/libarena.c
@@ -15,7 +15,12 @@ static void run_libarena_test(struct libarena *skel, struct bpf_program *prog,
 {
 	int ret;
 
-	if (!strstr(name, "test_buddy")) {
+	if (strstr(name, "test_buddy")) {
+		/* Buddy tests initialize the allocator directly. */
+		ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_destroy));
+		if (!ASSERT_OK(ret, "arena_buddy_destroy"))
+			return;
+	} else {
 		ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset));
 		if (!ASSERT_OK(ret, "arena_buddy_reset"))
 			return;
@@ -24,7 +29,6 @@ static void run_libarena_test(struct libarena *skel, struct bpf_program *prog,
 	ret = libarena_run_prog(bpf_program__fd(prog));
 
 	ASSERT_OK(ret, name);
-
 }
 
 static void *run_libarena_parallel_prog(void *arg)
diff --git a/tools/testing/selftests/bpf/prog_tests/libarena_asan.c b/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
index d59d9dd12ef2..f897405f701d 100644
--- a/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
+++ b/tools/testing/selftests/bpf/prog_tests/libarena_asan.c
@@ -17,7 +17,12 @@ static void run_libarena_asan_test(struct libarena_asan *skel,
 {
 	int ret;
 
-	if (!strstr(name, "test_buddy")) {
+	if (strstr(name, "test_buddy")) {
+		/* Buddy tests initialize the allocator directly. */
+		ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_destroy));
+		if (!ASSERT_OK(ret, "arena_buddy_destroy"))
+			return;
+	} else {
 		ret = libarena_run_prog(bpf_program__fd(skel->progs.arena_buddy_reset));
 		if (!ASSERT_OK(ret, "arena_buddy_reset"))
 			return;
@@ -90,4 +95,3 @@ void test_libarena_asan(void)
 
 	return;
 }
-
-- 
2.54.0

[PATCH bpf-next v3 3/5] selftests/bpf: Add arena-based bitmap data structure

[Emil Tsalapatis]

Add an arena-based word-aligned bitmap data struture. The
structure is useful as a building block, e.g., sched-ext
uses it to represent cpumask structures.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../bpf/libarena/include/libarena/bitmap.h    |  34 +++
 .../selftests/bpf/libarena/src/bitmap.bpf.c   | 245 ++++++++++++++++++
 2 files changed, 279 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/libarena/include/libarena/bitmap.h
 create mode 100644 tools/testing/selftests/bpf/libarena/src/bitmap.bpf.c

diff --git a/tools/testing/selftests/bpf/libarena/include/libarena/bitmap.h b/tools/testing/selftests/bpf/libarena/include/libarena/bitmap.h
new file mode 100644
index 000000000000..cf6b63f5d9a4
--- /dev/null
+++ b/tools/testing/selftests/bpf/libarena/include/libarena/bitmap.h
@@ -0,0 +1,34 @@
+#pragma once
+
+#define BITS_PER_BYTE		8
+#define BYTES_TO_BITS(nb)	((nb) * BITS_PER_BYTE)
+
+#define BITS_PER_LONG_LONG	(sizeof(long long) * BITS_PER_BYTE)
+#define BITS_TO_LONG_LONGS(nr)	(((nr) + BITS_PER_LONG_LONG - 1) / BITS_PER_LONG_LONG)
+#define BIT_MASK(nr)		(1ULL << ((nr) % BITS_PER_LONG_LONG))
+#define BIT_WORD(nr)		((nr) / BITS_PER_LONG_LONG)
+
+struct bitmap {
+	u64 bits[0];
+};
+
+struct bitmap __arena *bmp_alloc(size_t bits);
+void bmp_free(struct bitmap __arena *bmp);
+
+void __bmp_set_bit(u32 bit, struct bitmap __arena *bmp);
+void __bmp_clear_bit(u32 bit, struct bitmap __arena *bmp);
+void bmp_set_bit(u32 bit, struct bitmap __arena *bmp);
+void bmp_clear_bit(u32 bit, struct bitmap __arena *bmp);
+bool bmp_test_bit(u32 bit, struct bitmap __arena *bmp);
+bool bmp_test_and_clear_bit(u32 bit, struct bitmap __arena *bmp);
+bool bmp_test_and_set_bit(u32 bit, struct bitmap __arena *bmp);
+
+void bmp_clear(size_t bits, struct bitmap __arena *bmp);
+void bmp_and(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src1, struct bitmap __arena *src2);
+void bmp_or(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src1, struct bitmap __arena *src2);
+bool bmp_empty(size_t bits, struct bitmap __arena *bmp);
+void bmp_copy(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src);
+
+bool bmp_intersects(size_t bits, struct bitmap __arena *arg1, struct bitmap __arena *arg2);
+bool bmp_subset(size_t bits, struct bitmap __arena *big, struct bitmap __arena *small);
+void bmp_print(size_t bits, struct bitmap __arena *bmp);
diff --git a/tools/testing/selftests/bpf/libarena/src/bitmap.bpf.c b/tools/testing/selftests/bpf/libarena/src/bitmap.bpf.c
new file mode 100644
index 000000000000..80e814401fb9
--- /dev/null
+++ b/tools/testing/selftests/bpf/libarena/src/bitmap.bpf.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
+/*
+ * Copyright (c) 2025-2026 Meta Platforms, Inc. and affiliates.
+ * Copyright (c) 2025-2026 Emil Tsalapatis <emil@etsalapatis.com>
+ */
+
+#include <libarena/common.h>
+
+#include <libarena/asan.h>
+#include <libarena/bitmap.h>
+
+__weak
+struct bitmap __arena *bmp_alloc(size_t bits)
+{
+	struct bitmap __arena *bmp;
+	size_t size = BITS_TO_LONG_LONGS(bits) * sizeof(bmp->bits[0]);
+
+	/* Assume long-aligned masks. */
+	if (bits % BITS_PER_LONG_LONG)
+		return NULL;
+
+	bmp = (struct bitmap __arena *)arena_malloc(size);
+	if (!bmp)
+		return NULL;
+
+	bmp_clear(bits, bmp);
+
+	return bmp;
+}
+
+__weak
+void bmp_free(struct bitmap __arena *bmp)
+{
+	arena_free(bmp);
+}
+
+__weak
+void __bmp_set_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	bmp->bits[BIT_WORD(bit)] |= BIT_MASK(bit);
+}
+
+__weak
+void __bmp_clear_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	bmp->bits[BIT_WORD(bit)] &= ~BIT_MASK(bit);
+}
+
+__weak
+bool bmp_test_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	return bmp->bits[BIT_WORD(bit)] & BIT_MASK(bit);
+}
+
+__weak
+bool bmp_test_and_clear_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	u64 val = BIT_MASK(bit);
+	u32 idx = BIT_WORD(bit);
+	u64 old, new, actual;
+
+	do {
+		old = bmp->bits[idx];
+
+		if (!(old & val))
+			return false;
+
+		new = old & ~val;
+		actual = cmpxchg(&bmp->bits[idx], old, new);
+
+		if (actual == old)
+			return true;
+
+	} while (can_loop);
+
+	return false;
+}
+
+__weak
+bool bmp_test_and_set_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	u64 val = BIT_MASK(bit);
+	u32 idx = BIT_WORD(bit);
+	u64 old, new, actual;
+
+	do {
+		old = bmp->bits[idx];
+
+		if ((old & val))
+			return true;
+
+		new = old | val;
+		actual = cmpxchg(&bmp->bits[idx], old, new);
+
+		if (actual == old)
+			return false;
+
+	} while (can_loop);
+
+	return false;
+}
+
+__weak
+void bmp_clear_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	u64 val = BIT_MASK(bit);
+	u32 idx = BIT_WORD(bit);
+	u64 old, new, actual;
+
+	do {
+		old = bmp->bits[idx];
+		new = old & ~val;
+		actual = cmpxchg(&bmp->bits[idx], old, new);
+
+	} while (actual != old && can_loop);
+}
+
+__weak
+void bmp_set_bit(u32 bit, struct bitmap __arena *bmp)
+{
+	u64 val = BIT_MASK(bit);
+	u32 idx = BIT_WORD(bit);
+	u64 old, new, actual;
+
+	do {
+		old = bmp->bits[idx];
+		new = old | val;
+		actual = cmpxchg(&bmp->bits[idx], old, new);
+
+	} while (actual != old && can_loop);
+}
+
+__weak
+void bmp_clear(size_t bits, struct bitmap __arena *bmp)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++)
+		bmp->bits[i] = 0;
+}
+
+static __always_inline u64 bmp_last_word_mask(size_t bits)
+{
+	u32 rem = bits % BITS_PER_LONG_LONG;
+
+	return rem ? (1ULL << rem) - 1 : ~0ULL;
+}
+
+__weak
+void bmp_and(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src1, struct bitmap __arena *src2)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++)
+		dst->bits[i] = src1->bits[i] & src2->bits[i];
+
+	if (nwords && bits % BITS_PER_LONG_LONG)
+		dst->bits[nwords - 1] &= bmp_last_word_mask(bits);
+}
+
+__weak
+void bmp_or(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src1, struct bitmap __arena *src2)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++)
+		dst->bits[i] = src1->bits[i] | src2->bits[i];
+
+	if (nwords && bits % BITS_PER_LONG_LONG)
+		dst->bits[nwords - 1] &= bmp_last_word_mask(bits);
+}
+
+__weak
+bool bmp_empty(size_t bits, struct bitmap __arena *bmp)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++) {
+		u64 mask = (i == nwords - 1) ? bmp_last_word_mask(bits) : ~0ULL;
+
+		if (bmp->bits[i] & mask)
+			return false;
+	}
+
+	return true;
+}
+
+__weak
+void bmp_copy(size_t bits, struct bitmap __arena *dst, struct bitmap __arena *src)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++)
+		dst->bits[i] = src->bits[i];
+
+	if (nwords && bits % BITS_PER_LONG_LONG)
+		dst->bits[nwords - 1] &= bmp_last_word_mask(bits);
+}
+
+__weak
+bool bmp_subset(size_t bits, struct bitmap __arena *big, struct bitmap __arena *small)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++) {
+		u64 mask = (i == nwords - 1) ? bmp_last_word_mask(bits) : ~0ULL;
+
+		if (~big->bits[i] & small->bits[i] & mask)
+			return false;
+	}
+
+	return true;
+}
+
+__weak
+bool bmp_intersects(size_t bits, struct bitmap __arena *arg1, struct bitmap __arena *arg2)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++) {
+		u64 mask = (i == nwords - 1) ? bmp_last_word_mask(bits) : ~0ULL;
+
+		if (arg1->bits[i] & arg2->bits[i] & mask)
+			return true;
+	}
+
+	return false;
+}
+
+__weak
+void bmp_print(size_t bits, struct bitmap __arena *bmp)
+{
+	size_t nwords = BITS_TO_LONG_LONGS(bits);
+	volatile u32 i;
+
+	for (i = zero; i < nwords && can_loop; i++)
+		arena_stderr("%016llx ", bmp->bits[i]);
+}
-- 
2.54.0

Re: [PATCH bpf-next v3 3/5] selftests/bpf: Add arena-based bitmap data structure

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 530 bytes --]

> Add an arena-based word-aligned bitmap data struture. The
> structure is useful as a building block, e.g., sched-ext
> uses it to represent cpumask structures.
>
> Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>

this isn't a bug, but should "data struture" read "data structure"?


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/28553504082

[PATCH bpf-next v3 4/5] selftests/bpf: libarena: Add bitmap selftests

[Emil Tsalapatis]

Add testing for the new arena bitmap data structure.

Acked-by: Ihor Solodrai <ihor.solodrai@linux.dev>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../bpf/libarena/selftests/test_bitmap.bpf.c  | 394 ++++++++++++++++++
 1 file changed, 394 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/libarena/selftests/test_bitmap.bpf.c

diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_bitmap.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_bitmap.bpf.c
new file mode 100644
index 000000000000..e7d32f44d687
--- /dev/null
+++ b/tools/testing/selftests/bpf/libarena/selftests/test_bitmap.bpf.c
@@ -0,0 +1,394 @@
+#include <libarena/common.h>
+
+#include <libarena/asan.h>
+#include <libarena/bitmap.h>
+
+#define TEST_BITS	(2 * BITS_PER_LONG_LONG)
+#define TEST_WORDS	BITS_TO_LONG_LONGS(TEST_BITS)
+#define MID_BIT		(BITS_PER_LONG_LONG + 1)
+#define LAST_BIT	(TEST_BITS - 1)
+
+static void test_bmp_setall(struct bitmap __arena *bmp)
+{
+	volatile u32 i;
+
+	for (i = zero; i < TEST_WORDS && can_loop; i++)
+		bmp->bits[i] = ~0ULL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_alloc_free(void)
+{
+	struct bitmap __arena *bmp;
+
+	bmp = bmp_alloc(TEST_BITS);
+	if (!bmp)
+		return -ENOMEM;
+
+	if (!bmp_empty(TEST_BITS, bmp))
+		goto err;
+
+	__bmp_set_bit(LAST_BIT, bmp);
+	if (!bmp_test_bit(LAST_BIT, bmp))
+		goto err;
+
+	__bmp_clear_bit(LAST_BIT, bmp);
+	if (bmp_test_bit(LAST_BIT, bmp))
+		goto err;
+
+	bmp_free(bmp);
+	return 0;
+
+err:
+	bmp_free(bmp);
+	return -EINVAL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_bit_ops(void)
+{
+	struct bitmap __arena *bmp;
+
+	bmp = bmp_alloc(TEST_BITS);
+	if (!bmp)
+		return -ENOMEM;
+
+	__bmp_set_bit(0, bmp);
+	if (!bmp_test_bit(0, bmp))
+		goto err;
+
+	__bmp_set_bit(MID_BIT, bmp);
+	if (!bmp_test_bit(MID_BIT, bmp))
+		goto err;
+
+	__bmp_set_bit(LAST_BIT, bmp);
+	if (!bmp_test_bit(LAST_BIT, bmp))
+		goto err;
+
+	if (bmp_test_bit(MID_BIT - 1, bmp))
+		goto err;
+
+	__bmp_clear_bit(MID_BIT, bmp);
+	if (bmp_test_bit(MID_BIT, bmp))
+		goto err;
+
+	if (!bmp_test_bit(0, bmp))
+		goto err;
+
+	if (!bmp_test_bit(LAST_BIT, bmp))
+		goto err;
+
+	__bmp_clear_bit(0, bmp);
+	__bmp_clear_bit(LAST_BIT, bmp);
+	if (!bmp_empty(TEST_BITS, bmp))
+		goto err;
+
+	if (bmp->bits[0])
+		goto err;
+
+	if (bmp->bits[1])
+		goto err;
+
+	bmp_free(bmp);
+	return 0;
+
+err:
+	bmp_free(bmp);
+	return -EINVAL;
+}
+
+static bool test_bitmap_test_and_clear_single(struct bitmap __arena *bmp, size_t ind)
+{
+	if (bmp_test_and_clear_bit(ind, bmp))
+		return false;
+
+	__bmp_set_bit(ind, bmp);
+
+	if (!bmp_test_and_clear_bit(ind, bmp))
+		return false;
+
+	if (bmp_test_bit(ind, bmp))
+		return false;
+
+	if (bmp_test_and_clear_bit(ind, bmp))
+		return false;
+
+	return true;
+}
+
+static bool test_bitmap_test_and_set_single(struct bitmap __arena *bmp, size_t ind)
+{
+	if (bmp_test_and_set_bit(ind, bmp))
+		return false;
+
+	if (!bmp_test_and_set_bit(ind, bmp))
+		return false;
+
+	if (!bmp_test_bit(ind, bmp))
+		return false;
+
+	__bmp_clear_bit(ind, bmp);
+
+	if (bmp_test_and_set_bit(ind, bmp))
+		return false;
+
+	return true;
+}
+
+SEC("syscall")
+__weak int test_bitmap_test_and_clear_bit(void)
+{
+	struct bitmap __arena *bmp;
+
+	bmp = bmp_alloc(TEST_BITS);
+	if (!bmp)
+		return -ENOMEM;
+
+	if (!test_bitmap_test_and_clear_single(bmp, 0))
+		goto err;
+
+	if (!test_bitmap_test_and_clear_single(bmp, MID_BIT))
+		goto err;
+
+	if (!test_bitmap_test_and_clear_single(bmp, LAST_BIT))
+		goto err;
+
+	if (!bmp_empty(TEST_BITS, bmp))
+		goto err;
+
+	bmp_free(bmp);
+	return 0;
+
+err:
+	bmp_free(bmp);
+	return -EINVAL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_test_and_set_bit(void)
+{
+	struct bitmap __arena *bmp;
+
+	bmp = bmp_alloc(TEST_BITS);
+	if (!bmp)
+		return -ENOMEM;
+
+	if (!test_bitmap_test_and_set_single(bmp, 0))
+		goto err;
+
+	if (!test_bitmap_test_and_set_single(bmp, MID_BIT))
+		goto err;
+
+	if (!test_bitmap_test_and_set_single(bmp, LAST_BIT))
+		goto err;
+
+	bmp_free(bmp);
+	return 0;
+
+err:
+	bmp_free(bmp);
+	return -EINVAL;
+}
+
+
+SEC("syscall")
+__weak int test_bitmap_and(void)
+{
+	struct bitmap __arena *src1 = NULL, *src2 = NULL, *dst = NULL;
+
+	src1 = bmp_alloc(TEST_BITS);
+	src2 = bmp_alloc(TEST_BITS);
+	dst = bmp_alloc(TEST_BITS);
+	if (!src1 || !src2 || !dst)
+		goto err;
+
+	test_bmp_setall(dst);
+
+	__bmp_set_bit(0, src1);
+	__bmp_set_bit(MID_BIT, src1);
+	__bmp_set_bit(LAST_BIT, src1);
+
+	__bmp_set_bit(MID_BIT, src2);
+	__bmp_set_bit(LAST_BIT, src2);
+
+	bmp_and(TEST_BITS, dst, src1, src2);
+
+	if (bmp_test_bit(0, dst))
+		goto err;
+	if (!bmp_test_bit(MID_BIT, dst))
+		goto err;
+	if (!bmp_test_bit(LAST_BIT, dst))
+		goto err;
+
+	if (dst->bits[0])
+		goto err;
+	if (dst->bits[1] != (BIT_MASK(MID_BIT) | BIT_MASK(LAST_BIT)))
+		goto err;
+
+	bmp_free(src1);
+	bmp_free(src2);
+	bmp_free(dst);
+	return 0;
+
+err:
+	bmp_free(src1);
+	bmp_free(src2);
+	bmp_free(dst);
+	return -EINVAL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_or(void)
+{
+	struct bitmap __arena *src1 = NULL, *src2 = NULL, *dst = NULL;
+
+	src1 = bmp_alloc(TEST_BITS);
+	src2 = bmp_alloc(TEST_BITS);
+	dst = bmp_alloc(TEST_BITS);
+	if (!src1 || !src2 || !dst)
+		goto err;
+
+	test_bmp_setall(dst);
+
+	__bmp_set_bit(0, src1);
+	__bmp_set_bit(LAST_BIT, src1);
+
+	__bmp_set_bit(MID_BIT, src2);
+	__bmp_set_bit(LAST_BIT, src2);
+
+	bmp_or(TEST_BITS, dst, src1, src2);
+
+	if (!bmp_test_bit(0, dst))
+		goto err;
+	if (!bmp_test_bit(MID_BIT, dst))
+		goto err;
+	if (!bmp_test_bit(LAST_BIT, dst))
+		goto err;
+
+	if (dst->bits[0] != BIT_MASK(0))
+		goto err;
+	if (dst->bits[1] != (BIT_MASK(MID_BIT) | BIT_MASK(LAST_BIT)))
+		goto err;
+
+	bmp_free(src1);
+	bmp_free(src2);
+	bmp_free(dst);
+	return 0;
+
+err:
+	bmp_free(src1);
+	bmp_free(src2);
+	bmp_free(dst);
+	return -EINVAL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_subset(void)
+{
+	struct bitmap __arena *big = NULL, *small = NULL;
+
+	big = bmp_alloc(TEST_BITS);
+	small = bmp_alloc(TEST_BITS);
+	if (!big || !small)
+		goto err;
+
+	if (!bmp_subset(TEST_BITS, big, small))
+		goto err;
+
+	__bmp_set_bit(0, small);
+	if (bmp_subset(TEST_BITS, big, small))
+		goto err;
+
+	__bmp_set_bit(0, big);
+	if (!bmp_subset(TEST_BITS, big, small))
+		goto err;
+
+	__bmp_set_bit(LAST_BIT, small);
+	if (bmp_subset(TEST_BITS, big, small))
+		goto err;
+
+	__bmp_set_bit(LAST_BIT, big);
+	__bmp_set_bit(MID_BIT, big);
+	if (!bmp_subset(TEST_BITS, big, small))
+		goto err;
+
+	if (bmp_subset(TEST_BITS, small, big))
+		goto err;
+
+	bmp_free(big);
+	bmp_free(small);
+	return 0;
+
+err:
+	bmp_free(big);
+	bmp_free(small);
+	return -EINVAL;
+
+}
+
+SEC("syscall")
+__weak int test_bitmap_intersects(void)
+{
+	struct bitmap __arena *arg1 = NULL, *arg2 = NULL;
+
+	arg1 = bmp_alloc(TEST_BITS);
+	arg2 = bmp_alloc(TEST_BITS);
+	if (!arg1 || !arg2)
+		goto err;
+
+	if (bmp_intersects(TEST_BITS, arg1, arg2))
+		goto err;
+
+	__bmp_set_bit(0, arg1);
+	__bmp_set_bit(MID_BIT, arg2);
+	if (bmp_intersects(TEST_BITS, arg1, arg2))
+		goto err;
+
+	__bmp_set_bit(LAST_BIT, arg1);
+	__bmp_set_bit(LAST_BIT, arg2);
+	if (!bmp_intersects(TEST_BITS, arg1, arg2))
+		goto err;
+
+	bmp_free(arg1);
+	bmp_free(arg2);
+	return 0;
+
+err:
+	bmp_free(arg1);
+	bmp_free(arg2);
+	return -EINVAL;
+}
+
+SEC("syscall")
+__weak int test_bitmap_copy(void)
+{
+	struct bitmap __arena *arg1 = NULL, *arg2 = NULL;
+
+	arg1 = bmp_alloc(TEST_BITS);
+	arg2 = bmp_alloc(TEST_BITS);
+	if (!arg1 || !arg2)
+		goto err;
+
+	__bmp_set_bit(0, arg1);
+	__bmp_set_bit(MID_BIT, arg1);
+
+	/* Make sure those get overwritten. */
+	__bmp_set_bit(1, arg2);
+	__bmp_set_bit(MID_BIT + 2, arg2);
+
+	bmp_copy(TEST_BITS, arg2, arg1);
+
+	/* Bitmaps are equal if a subset of each other. */
+	if (!bmp_subset(TEST_BITS, arg1, arg2) ||
+	    !bmp_subset(TEST_BITS, arg2, arg1))
+		goto err;
+
+	bmp_free(arg1);
+	bmp_free(arg2);
+	return 0;
+
+err:
+	bmp_free(arg1);
+	bmp_free(arg2);
+	return -EINVAL;
+}
-- 
2.54.0

[PATCH bpf-next v3 5/5] selftests/bpf: libarena: Add parallel bitmap selftest

[Emil Tsalapatis]

Add a selftest for testing the atomic bitmap set/clear/
test_and_set/test_and_clear operations. The selftest
checks atomicity by spawning two threads, each of which
either only works on even bits or with odd bits. The
test checks that threads do not affect each other's
bits.

Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
---
 .../selftests/test_parallel_bitmap.bpf.c      | 190 ++++++++++++++++++
 1 file changed, 190 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/libarena/selftests/test_parallel_bitmap.bpf.c

diff --git a/tools/testing/selftests/bpf/libarena/selftests/test_parallel_bitmap.bpf.c b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_bitmap.bpf.c
new file mode 100644
index 000000000000..eec2871e2b0d
--- /dev/null
+++ b/tools/testing/selftests/bpf/libarena/selftests/test_parallel_bitmap.bpf.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: LGPL-2.1 OR BSD-2-Clause
+
+#include <bpf_atomic.h>
+
+#include <libarena/common.h>
+
+#include <libarena/asan.h>
+#include <libarena/bitmap.h>
+
+#define TEST_BITMAP_THREADS	2
+#define TEST_BITMAP_BITS	(2 * BITS_PER_LONG_LONG)
+#define TEST_BITMAP_SYNC_SPINS	BPF_MAX_LOOPS
+#define TEST_BITMAP_ITERS	10 * 1000 * 1000
+
+static struct bitmap __arena *bitmap;
+static volatile u64 started;
+static volatile bool test_abort;
+
+/*
+ * The test needs cmpxchg atomics on arena memory.
+ */
+#if defined(ENABLE_ATOMICS_TESTS) &&				  \
+	(defined(__TARGET_ARCH_arm64) || defined(__TARGET_ARCH_x86) || \
+	 defined(__TARGET_ARCH_s390) || \
+	 defined(__TARGET_ARCH_powerpc) ||				  \
+	 (defined(__TARGET_ARCH_riscv) && __riscv_xlen == 64))
+static bool bitmap_tests_enabled(void)
+{
+	return true;
+}
+#else
+static bool bitmap_tests_enabled(void)
+{
+	return false;
+}
+#endif
+
+__weak
+int bitmap_wait_for_start(void)
+{
+	u64 i;
+
+	__sync_fetch_and_add(&started, 1);
+
+	for (i = zero; i < TEST_BITMAP_SYNC_SPINS && can_loop; i++) {
+		if (test_abort)
+			return -EINTR;
+		if (smp_load_acquire(&started) >= TEST_BITMAP_THREADS)
+			return 0;
+	}
+
+	test_abort = true;
+	return -ETIMEDOUT;
+}
+
+/*
+ * The test makes sure writes don't clobber each other by overwriting
+ * the same word. One thread always writes on even bits, the other on
+ * odds. Both should be able to operate on the bitmap oblivious of the
+ * other's operations.
+ */
+__weak
+int bitmap_test_bit_sequence(u32 bit)
+{
+	if (bmp_test_and_clear_bit(bit, bitmap))
+		return -EINVAL;
+
+	if (bmp_test_and_set_bit(bit, bitmap))
+		return -EINVAL;
+	if (!bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	if (!bmp_test_and_set_bit(bit, bitmap))
+		return -EINVAL;
+	if (!bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	if (!bmp_test_and_clear_bit(bit, bitmap))
+		return -EINVAL;
+	if (bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	if (bmp_test_and_clear_bit(bit, bitmap))
+		return -EINVAL;
+
+	bmp_set_bit(bit, bitmap);
+	if (!bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	bmp_clear_bit(bit, bitmap);
+	if (bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	bmp_set_bit(bit, bitmap);
+	if (!bmp_test_bit(bit, bitmap))
+		return -EINVAL;
+
+	return 0;
+
+}
+
+static void bitmap_test_reset_single(int parity)
+{
+	u32 bit;
+
+	for (bit = parity; bit < TEST_BITMAP_BITS && can_loop; bit += 2)
+		bmp_clear_bit(bit, bitmap);
+
+}
+
+static int bitmap_test_common_single(int parity)
+{
+	u32 bit;
+	int ret;
+
+	for (bit = parity; bit < TEST_BITMAP_BITS && can_loop; bit += 2) {
+		if (test_abort)
+			return -EINTR;
+
+		ret = bitmap_test_bit_sequence(bit);
+		if (ret) {
+			test_abort = true;
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int bitmap_test_common(int parity)
+{
+	int ret;
+	u32 i;
+
+	arena_subprog_init();
+
+	ret = bitmap_wait_for_start();
+	if (ret)
+		return ret;
+
+	for (i = zero; i < TEST_BITMAP_ITERS && can_loop; i++) {
+		ret = bitmap_test_common_single(parity);
+		if (ret)
+			return ret;
+
+		if (test_abort)
+			break;
+
+		bitmap_test_reset_single(parity);
+	}
+
+	return 0;
+}
+
+SEC("syscall") int parallel_test_bitmap__enabled(void)
+{
+	return bitmap_tests_enabled() ? 0 : -EOPNOTSUPP;
+}
+
+SEC("syscall") int parallel_test_bitmap__init(void)
+{
+	bitmap = bmp_alloc(TEST_BITMAP_BITS);
+	if (!bitmap)
+		return -ENOMEM;
+
+	return 0;
+}
+
+SEC("syscall") int parallel_test_bitmap__fini(void)
+{
+	int ret = 0;
+
+	if (!bitmap)
+		return -EINVAL;
+
+	bmp_free(bitmap);
+	bitmap = NULL;
+
+	return ret;
+}
+
+SEC("syscall") int parallel_test_bitmap__0(void)
+{
+	return bitmap_test_common(0);
+}
+
+SEC("syscall") int parallel_test_bitmap__1(void)
+{
+	return bitmap_test_common(1);
+}
-- 
2.54.0