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selftests/bpf: Fix test_core_autosize on big-endian machines

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The "probed" part of test_core_autosize copies an integer using
bpf_core_read() into an integer of a potentially different size.
On big-endian machines a destination offset is required for this to
produce a sensible result.

Fixes: 888d83b961 ("selftests/bpf: Validate libbpf's auto-sizing of LD/ST/STX instructions")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210812224814.187460-1-iii@linux.ibm.com
This commit is contained in:
Ilya Leoshkevich 2021-08-13 00:48:14 +02:00 committed by Andrii Nakryiko
parent 2211c825e7
commit d164dd9a5c
1 changed files with 15 additions and 5 deletions
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20
tools/testing/selftests/bpf/progs/test_core_autosize.c
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@ -125,6 +125,16 @@ int handle_downsize(void *ctx)
return 0;
}
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define bpf_core_read_int bpf_core_read
#else
#define bpf_core_read_int(dst, sz, src) ({ \
/* Prevent "subtraction from stack pointer prohibited" */ \
volatile long __off = sizeof(*dst) - (sz); \
bpf_core_read((char *)(dst) + __off, sz, src); \
})
#endif
SEC("raw_tp/sys_enter")
int handle_probed(void *ctx)
{
@ -132,23 +142,23 @@ int handle_probed(void *ctx)
__u64 tmp;
tmp = 0;
bpf_core_read(&tmp, bpf_core_field_size(in->ptr), &in->ptr);
bpf_core_read_int(&tmp, bpf_core_field_size(in->ptr), &in->ptr);
ptr_probed = tmp;
tmp = 0;
bpf_core_read(&tmp, bpf_core_field_size(in->val1), &in->val1);
bpf_core_read_int(&tmp, bpf_core_field_size(in->val1), &in->val1);
val1_probed = tmp;
tmp = 0;
bpf_core_read(&tmp, bpf_core_field_size(in->val2), &in->val2);
bpf_core_read_int(&tmp, bpf_core_field_size(in->val2), &in->val2);
val2_probed = tmp;
tmp = 0;
bpf_core_read(&tmp, bpf_core_field_size(in->val3), &in->val3);
bpf_core_read_int(&tmp, bpf_core_field_size(in->val3), &in->val3);
val3_probed = tmp;
tmp = 0;
bpf_core_read(&tmp, bpf_core_field_size(in->val4), &in->val4);
bpf_core_read_int(&tmp, bpf_core_field_size(in->val4), &in->val4);
val4_probed = tmp;
return 0;