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selftests/bpf: bpf_rdonly_cast u{8,16,32,64} access tests

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Tests with aligned and misaligned memory access of different sizes via
pointer returned by bpf_rdonly_cast().

Suggested-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20250627015539.1439656-1-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Eduard Zingerman 2025-06-26 18:55:39 -07:00 committed by Alexei Starovoitov
parent ffaff1804e
commit c4b1be928e
1 changed files with 41 additions and 0 deletions
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41
tools/testing/selftests/bpf/progs/mem_rdonly_untrusted.c
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@ -133,4 +133,45 @@ int mixed_mem_type(void *ctx)
return *p;
}
__attribute__((__aligned__(8)))
u8 global[] = {
0x11, 0x22, 0x33, 0x44,
0x55, 0x66, 0x77, 0x88,
0x99
};
__always_inline
static u64 combine(void *p)
{
u64 acc;
acc = 0;
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
acc |= (*(u64 *)p >> 56) << 24;
acc |= (*(u32 *)p >> 24) << 16;
acc |= (*(u16 *)p >> 8) << 8;
acc |= *(u8 *)p;
#else
acc |= (*(u64 *)p & 0xff) << 24;
acc |= (*(u32 *)p & 0xff) << 16;
acc |= (*(u16 *)p & 0xff) << 8;
acc |= *(u8 *)p;
#endif
return acc;
}
SEC("socket")
__retval(0x88442211)
int diff_size_access(void *ctx)
{
return combine(bpf_rdonly_cast(&global, 0));
}
SEC("socket")
__retval(0x99553322)
int misaligned_access(void *ctx)
{
return combine(bpf_rdonly_cast(&global, 0) + 1);
}
char _license[] SEC("license") = "GPL";