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: 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

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

@@ -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

@@ -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

@@ -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