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ff943683f8
Fix how selftests determine relative offset of a function that is
uprobed. Previously, there was an assumption that uprobed function is
always in the first executable region, which is not always the case
(libbpf CI hits this case now). So get_base_addr() approach in isolation
doesn't work anymore. So teach get_uprobe_offset() to determine correct
memory mapping and calculate uprobe offset correctly.
While at it, I merged together two implementations of
get_uprobe_offset() helper, moving powerpc64-specific logic inside (had
to add extra {} block to avoid unused variable error for insn).
Also ensured that uprobed functions are never inlined, but are still
static (and thus local to each selftest), by using a no-op asm volatile
block internally. I didn't want to keep them global __weak, because some
tests use uprobe's ref counter offset (to test USDT-like logic) which is
not compatible with non-refcounted uprobe. So it's nicer to have each
test uprobe target local to the file and guaranteed to not be inlined or
skipped by the compiler (which can happen with static functions,
especially if compiling selftests with -O2).
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220126193058.3390292-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
24 lines
521 B
C
24 lines
521 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __TRACE_HELPER_H
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#define __TRACE_HELPER_H
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#include <bpf/libbpf.h>
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struct ksym {
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long addr;
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char *name;
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};
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int load_kallsyms(void);
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struct ksym *ksym_search(long key);
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long ksym_get_addr(const char *name);
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/* open kallsyms and find addresses on the fly, faster than load + search. */
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int kallsyms_find(const char *sym, unsigned long long *addr);
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void read_trace_pipe(void);
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ssize_t get_uprobe_offset(const void *addr);
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ssize_t get_rel_offset(uintptr_t addr);
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#endif
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