Commit a549aaa6 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Daniel Borkmann
Browse files

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



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: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210815070609.987780-14-andrii@kernel.org
parent f36d3557

tools/testing/selftests/bpf/prog_tests/attach_probe.c

+1 −60
Original line number Diff line number Diff line
@@ -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"))

tools/testing/selftests/bpf/trace_helpers.c

+66 −0
Original line number Diff line number Diff line
@@ -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;

}

tools/testing/selftests/bpf/trace_helpers.h

+3 −0
Original line number Diff line number Diff line
@@ -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