libbpf-tools: Avoid virtual memory area [uprobes] warning

Refer to kernel commit 704bde3cc26a ("uprobes: Use vm_special_mapping to
name the XOL vma"), processes setup the [uprobes] special virtual memory
area with uprobe events to excute original instruction out of line.

open_elf() would throw a warning of 'Could not open [uprobes]' when
attaching uprobes. For example, use memleak to trace userspace apps
allocations with command 'memleak -c <command>' or 'memleak -p <pid>':

    ~ # ps | grep dropbear
       76 root      2100 S    dropbear
       79 root      2340 S    grep dropbear
    ~ # memleak -p 76
    using default object: libc.so.6
    using page size: 4096
    tracing kernel: false
    Tracing outstanding memory allocs...  Hit Ctrl-C to end
    [0:18:54] Top 3 stacks with outstanding allocations:
    147 bytes in 1 allocations from stack
    Could not open [uprobes]
            0 [<000000000001b3bc>] free+0x7b2c [/bin/dropbear]
    64 bytes in 1 allocations from stack
            0 [<00000000000288c8>] free+0x15038 [/bin/dropbear]

So remove '[uprobes]' from get_elf_type() to avoid this warning.

Signed-off-by: mickey_zhu <[email protected]>

libbpf-tools/trace_helpers.c

@@ -243,6 +243,7 @@ static bool is_file_backed(const char *mapname)
 		STARTS_WITH(mapname, "[stack") ||
 		STARTS_WITH(mapname, "/SYSV") ||
 		STARTS_WITH(mapname, "[heap]") ||
+		STARTS_WITH(mapname, "[uprobes]") ||
 		STARTS_WITH(mapname, "[vsyscall]"));
 }
 
@@ -256,6 +257,11 @@ static bool is_vdso(const char *path)
 	return !strcmp(path, "[vdso]");
 }
 
+static bool is_uprobes(const char *path)
+{
+	return !strcmp(path, "[uprobes]");
+}
+
 static int get_elf_type(const char *path)
 {
 	GElf_Ehdr hdr;
@@ -265,6 +271,8 @@ static int get_elf_type(const char *path)
 
 	if (is_vdso(path))
 		return -1;
+	if (is_uprobes(path))
+		return -1;
 	e = open_elf(path, &fd);
 	if (!e)
 		return -1;