2023-02-24 15:19:02

by Rong Tao

Subject: [PATCH bpf-next v2] selftests/bpf: Fix compilation errors: assign a value to a constant

From: Rong Tao <[email protected]>

commit bc292ab00f6c("mm: introduce vma->vm_flags wrapper functions")
turns the vm_flags into a const variable.

Added bpf_find_vma test in commit f108662b27c9("selftests/bpf: Add tests
for bpf_find_vma") to assign values to variables that declare const in
find_vma_fail1.c programs, which is an error to the compiler and does not
test BPF verifiers. It is better to replace 'const vm_flags_t vm_flags'
with 'unsigned long vm_start' for testing.

$ make -C tools/testing/selftests/bpf/ -j8
...
progs/find_vma_fail1.c:16:16: error: cannot assign to non-static data
member 'vm_flags' with const-qualified type 'const vm_flags_t' (aka
'const unsigned long')
vma->vm_flags |= 0x55;
~~~~~~~~~~~~~ ^
../tools/testing/selftests/bpf/tools/include/vmlinux.h:1898:20:
note: non-static data member 'vm_flags' declared const here
const vm_flags_t vm_flags;
~~~~~~~~~~~`~~~~~~^~~~~~~~

Signed-off-by: Rong Tao <[email protected]>
---
v2: Add more useful commit information
v1: https://lore.kernel.org/lkml/[email protected]/
---
tools/testing/selftests/bpf/progs/find_vma_fail1.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/progs/find_vma_fail1.c b/tools/testing/selftests/bpf/progs/find_vma_fail1.c
index b3b326b8e2d1..47d5dedff554 100644
--- a/tools/testing/selftests/bpf/progs/find_vma_fail1.c
+++ b/tools/testing/selftests/bpf/progs/find_vma_fail1.c
@@ -13,7 +13,7 @@ static long write_vma(struct task_struct *task, struct vm_area_struct *vma,
struct callback_ctx *data)
{
/* writing to vma, which is illegal */
- vma->vm_flags |= 0x55;
+ vma->vm_start = 0xffffffffff600000;

return 0;
}
--
2.39.2

2023-02-27 19:50:24

by patchwork-bot+netdevbpf

Subject: Re: [PATCH bpf-next v2] selftests/bpf: Fix compilation errors: assign a value to a constant

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <[email protected]>:

On Fri, 24 Feb 2023 23:10:02 +0800 you wrote:
> From: Rong Tao <[email protected]>
>
> commit bc292ab00f6c("mm: introduce vma->vm_flags wrapper functions")
> turns the vm_flags into a const variable.
>
> Added bpf_find_vma test in commit f108662b27c9("selftests/bpf: Add tests
> for bpf_find_vma") to assign values to variables that declare const in
> find_vma_fail1.c programs, which is an error to the compiler and does not
> test BPF verifiers. It is better to replace 'const vm_flags_t vm_flags'
> with 'unsigned long vm_start' for testing.
>
> [...]

Here is the summary with links:
- [bpf-next,v2] selftests/bpf: Fix compilation errors: assign a value to a constant
https://git.kernel.org/bpf/bpf-next/c/11e456cae91e

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html