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selftests/bpf: Extract uprobe-related helpers into trace_helpers.{c,h}

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Extract two helpers used for working with uprobes into trace_helpers.{c,h} to
be re-used between multiple uprobe-using selftests. Also rename get_offset()
into more appropriate get_uprobe_offset().

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-14-andrii@kernel.org
This commit is contained in:
Andrii Nakryiko 2021-08-15 00:06:06 -07:00 committed by Daniel Borkmann
parent f36d3557a1
commit a549aaa673
3 changed files with 70 additions and 60 deletions
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61
tools/testing/selftests/bpf/prog_tests/attach_probe.c
View File

@ -2,65 +2,6 @@
#include <test_progs.h>
#include "test_attach_probe.skel.h"
#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
#define OP_RT_RA_MASK 0xffff0000UL
#define LIS_R2 0x3c400000UL
#define ADDIS_R2_R12 0x3c4c0000UL
#define ADDI_R2_R2 0x38420000UL
static ssize_t get_offset(ssize_t addr, ssize_t base)
{
u32 *insn = (u32 *) addr;
/*
* A PPC64 ABIv2 function may have a local and a global entry
* point. We need to use the local entry point when patching
* functions, so identify and step over the global entry point
* sequence.
*
* The global entry point sequence is always of the form:
*
* addis r2,r12,XXXX
* addi r2,r2,XXXX
*
* A linker optimisation may convert the addis to lis:
*
* lis r2,XXXX
* addi r2,r2,XXXX
*/
if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
return (ssize_t)(insn + 2) - base;
else
return addr - base;
}
#else
#define get_offset(addr, base) (addr - base)
#endif
ssize_t get_base_addr() {
size_t start, offset;
char buf[256];
FILE *f;
f = fopen("/proc/self/maps", "r");
if (!f)
return -errno;
while (fscanf(f, "%zx-%*x %s %zx %*[^\n]\n",
&start, buf, &offset) == 3) {
if (strcmp(buf, "r-xp") == 0) {
fclose(f);
return start - offset;
}
}
fclose(f);
return -EINVAL;
}
void test_attach_probe(void)
{
int duration = 0;
@ -74,7 +15,7 @@ void test_attach_probe(void)
if (CHECK(base_addr < 0, "get_base_addr",
"failed to find base addr: %zd", base_addr))
return;
uprobe_offset = get_offset((size_t)&get_base_addr, base_addr);
uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
skel = test_attach_probe__open_and_load();
if (CHECK(!skel, "skel_open", "failed to open skeleton\n"))

66
tools/testing/selftests/bpf/trace_helpers.c
View File

@ -136,3 +136,69 @@ void read_trace_pipe(void)
}
}
}
#if defined(__powerpc64__) && defined(_CALL_ELF) && _CALL_ELF == 2
#define OP_RT_RA_MASK 0xffff0000UL
#define LIS_R2 0x3c400000UL
#define ADDIS_R2_R12 0x3c4c0000UL
#define ADDI_R2_R2 0x38420000UL
ssize_t get_uprobe_offset(const void *addr, ssize_t base)
{
u32 *insn = (u32 *)(uintptr_t)addr;
/*
* A PPC64 ABIv2 function may have a local and a global entry
* point. We need to use the local entry point when patching
* functions, so identify and step over the global entry point
* sequence.
*
* The global entry point sequence is always of the form:
*
* addis r2,r12,XXXX
* addi r2,r2,XXXX
*
* A linker optimisation may convert the addis to lis:
*
* lis r2,XXXX
* addi r2,r2,XXXX
*/
if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
((*(insn + 1) & OP_RT_RA_MASK) == ADDI_R2_R2))
return (ssize_t)(insn + 2) - base;
else
return (uintptr_t)addr - base;
}
#else
ssize_t get_uprobe_offset(const void *addr, ssize_t base)
{
return (uintptr_t)addr - base;
}
#endif
ssize_t get_base_addr(void)
{
size_t start, offset;
char buf[256];
FILE *f;
f = fopen("/proc/self/maps", "r");
if (!f)
return -errno;
while (fscanf(f, "%zx-%*x %s %zx %*[^\n]\n",
&start, buf, &offset) == 3) {
if (strcmp(buf, "r-xp") == 0) {
fclose(f);
return start - offset;
}
}
fclose(f);
return -EINVAL;
}

3
tools/testing/selftests/bpf/trace_helpers.h
View File

@ -18,4 +18,7 @@ int kallsyms_find(const char *sym, unsigned long long *addr);
void read_trace_pipe(void);
ssize_t get_uprobe_offset(const void *addr, ssize_t base);
ssize_t get_base_addr(void);
#endif