commit f294197b5511537e6b14d5e1db324f4fc4fdd3f8
Author: Dave Anderson <anderson@redhat.com>
Date:   Fri Jul 6 10:57:50 2018 -0400

    Support for the "bpf" command on RHEL 3.10.0-913.el7 and later
    3.10-based RHEL7 kernels, which contain a backport of the upstream
    eBPF code, but still use the older, pre-4.11, IDR facility that does
    not use radix trees for linking the active bpf_prog and bpf_map
    structures.  Without the patch, the command indicates "bpf: command
    not supported or applicable on this architecture or kernel".
    (anderson@redhat.com)

diff --git a/bpf.c b/bpf.c
index 427263d..8871b76 100644
--- a/bpf.c
+++ b/bpf.c
@@ -45,6 +45,10 @@ static void bpf_prog_gpl_compatible(char *, ulong);
 static void dump_xlated_plain(void *, unsigned int, int);
 static void print_boot_time(unsigned long long, char *, unsigned int);
 
+static int do_old_idr(int, ulong, struct radix_tree_pair *);
+#define OLD_IDR_INIT   (1)
+#define OLD_IDR_COUNT  (2)
+#define OLD_IDR_GATHER (3)
 
 #define PROG_ID        (0x1)
 #define MAP_ID         (0x2)
@@ -167,7 +171,6 @@ bpf_init(struct bpf_info *bpf)
 		    !VALID_STRUCT(bpf_map) ||
 		    !VALID_STRUCT(bpf_insn) ||
 		    INVALID_MEMBER(bpf_prog_aux) ||
-		    INVALID_MEMBER(idr_idr_rt) ||
 		    INVALID_MEMBER(bpf_prog_type) ||
 		    INVALID_MEMBER(bpf_prog_tag) ||
 		    INVALID_MEMBER(bpf_prog_jited_len) ||
@@ -210,6 +213,9 @@ bpf_init(struct bpf_info *bpf)
 			mkstring(buf2, VADDR_PRLEN, CENTER|LJUST, "BPF_MAP"),
 			mkstring(buf3, bpf->bpf_map_map_type_size, CENTER|LJUST, "BPF_MAP_TYPE"));
 
+		if (INVALID_MEMBER(idr_idr_rt))
+			do_old_idr(OLD_IDR_INIT, 0, NULL);
+
 		bpf->status = TRUE;
 		break;
 
@@ -220,24 +226,38 @@ bpf_init(struct bpf_info *bpf)
 		command_not_supported();
 	}
 
-	bpf->progs = do_radix_tree(symbol_value("prog_idr") + OFFSET(idr_idr_rt),
-		RADIX_TREE_COUNT, NULL);
+	if (VALID_MEMBER(idr_idr_rt))
+		bpf->progs = do_radix_tree(symbol_value("prog_idr") + OFFSET(idr_idr_rt),
+			RADIX_TREE_COUNT, NULL);
+	else 
+		bpf->progs = do_old_idr(OLD_IDR_COUNT, symbol_value("prog_idr"), NULL);
+
 	if (bpf->progs) {
 		len = sizeof(struct radix_tree_pair) * (bpf->progs+1);
 		bpf->proglist = (struct radix_tree_pair *)GETBUF(len);
 		bpf->proglist[0].index = bpf->progs;
-		bpf->progs = do_radix_tree(symbol_value("prog_idr") + OFFSET(idr_idr_rt),
-			RADIX_TREE_GATHER, bpf->proglist);
+		if (VALID_MEMBER(idr_idr_rt))
+			bpf->progs = do_radix_tree(symbol_value("prog_idr") + OFFSET(idr_idr_rt),
+				RADIX_TREE_GATHER, bpf->proglist);
+		else
+			bpf->progs = do_old_idr(OLD_IDR_GATHER, symbol_value("prog_idr"), bpf->proglist);
 	}
 
-	bpf->maps = do_radix_tree(symbol_value("map_idr") + OFFSET(idr_idr_rt), 
-		RADIX_TREE_COUNT, NULL);
+	if (VALID_MEMBER(idr_idr_rt))
+		bpf->maps = do_radix_tree(symbol_value("map_idr") + OFFSET(idr_idr_rt), 
+			RADIX_TREE_COUNT, NULL);
+	else
+		bpf->maps = do_old_idr(OLD_IDR_COUNT, symbol_value("map_idr"), NULL);
+
 	if (bpf->maps) {
 		len = sizeof(struct radix_tree_pair) * (bpf->maps+1);
 		bpf->maplist = (struct radix_tree_pair *)GETBUF(len);
 		bpf->maplist[0].index = bpf->maps;
-		bpf->maps = do_radix_tree(symbol_value("map_idr") + OFFSET(idr_idr_rt),
-			RADIX_TREE_GATHER, bpf->maplist);
+		if (VALID_MEMBER(idr_idr_rt))
+			bpf->maps = do_radix_tree(symbol_value("map_idr") + OFFSET(idr_idr_rt),
+				RADIX_TREE_GATHER, bpf->maplist);
+		else
+			bpf->maps = do_old_idr(OLD_IDR_GATHER, symbol_value("map_idr"), bpf->maplist);
 	}
 
 	bpf->bpf_prog_buf = GETBUF(SIZE(bpf_prog));
@@ -538,8 +558,10 @@ do_map_only:
 	}
 
 bailout:
-	FREEBUF(bpf->proglist);
-	FREEBUF(bpf->maplist);
+	if (bpf->proglist)
+		FREEBUF(bpf->proglist);
+	if (bpf->maplist)
+		FREEBUF(bpf->maplist);
 	FREEBUF(bpf->bpf_prog_buf);
 	FREEBUF(bpf->bpf_prog_aux_buf);
 	FREEBUF(bpf->bpf_map_buf);
@@ -1255,3 +1277,50 @@ print_boot_time(unsigned long long nsecs, char *buf, unsigned int size)
 	sprintf(buf, "(unknown)");
 #endif
 }
+
+/*
+ *  Borrow the old (pre-radix_tree) IDR facility code used by
+ *  the ipcs command.
+ */
+static int
+do_old_idr(int cmd, ulong idr, struct radix_tree_pair *rtp)
+{
+	int i, max, cur, next_id, total = 0;
+	ulong entry;
+
+	switch (cmd)
+	{
+	case OLD_IDR_INIT:
+		ipcs_init();
+		break;
+
+	case OLD_IDR_COUNT:
+		readmem(idr + OFFSET(idr_cur), KVADDR, &cur, 
+			sizeof(int), "idr.cur", FAULT_ON_ERROR);
+		for (total = next_id = 0; next_id < cur; next_id++) {
+			entry = idr_find(idr, next_id);
+			if (entry == 0)
+				continue;
+			total++;
+		}
+		break;
+
+	case OLD_IDR_GATHER:
+		max = rtp[0].index;
+		readmem(idr + OFFSET(idr_cur), KVADDR, &cur, 
+			sizeof(int), "idr.cur", FAULT_ON_ERROR);
+		for (i = total = next_id = 0; next_id < cur; next_id++) {
+			entry = idr_find(idr, next_id);
+			if (entry == 0)
+				continue;
+			total++;
+			rtp[i].index = next_id;
+			rtp[i].value = (void *)entry;
+			if (++i == max)
+				break;
+		}
+		break;
+	}
+
+	return total;
+}
diff --git a/defs.h b/defs.h
index e6e3850..b05aecc 100644
--- a/defs.h
+++ b/defs.h
@@ -2031,6 +2031,7 @@ struct offset_table {                    /* stash of commonly-used offsets */
 	long bpf_prog_aux_load_time;
 	long bpf_prog_aux_user;
 	long user_struct_uid;
+	long idr_cur;
 };
 
 struct size_table {         /* stash of commonly-used sizes */
@@ -5590,6 +5591,12 @@ enum {
 void dev_init(void);
 void dump_dev_table(void);
 
+/*
+ *  ipcs.c
+ */
+void ipcs_init(void);
+ulong idr_find(ulong, int);
+
 #ifdef ARM
 void arm_init(int);
 void arm_dump_machdep_table(ulong);
diff --git a/ipcs.c b/ipcs.c
index ef51fdd..80f78e4 100644
--- a/ipcs.c
+++ b/ipcs.c
@@ -79,13 +79,11 @@ struct ipcs_table {
  * function declaration
  */
 
-static void ipcs_init(void);
 static int dump_shared_memory(int, ulong, int, ulong);
 static int dump_semaphore_arrays(int, ulong, int, ulong);
 static int dump_message_queues(int, ulong, int, ulong);
 static int ipc_search_idr(ulong, int, ulong, int (*)(ulong, int, ulong, int, int), int);
 static int ipc_search_array(ulong, int, ulong, int (*)(ulong, int, ulong, int, int), int);
-static ulong idr_find(ulong, int);
 static int dump_shm_info(ulong, int, ulong, int, int);
 static int dump_sem_info(ulong, int, ulong, int, int);
 static int dump_msg_info(ulong, int, ulong, int, int);
@@ -101,7 +99,7 @@ static void gather_radix_tree_entries(ulong);
  */
 static struct ipcs_table ipcs_table = { 0 };
 
-static void
+void
 ipcs_init(void)
 {
 	if (ipcs_table.init_flags & IPCS_INIT) {
@@ -119,6 +117,7 @@ ipcs_init(void)
 	MEMBER_OFFSET_INIT(idr_layer_layer, "idr_layer", "layer");
 	MEMBER_OFFSET_INIT(idr_layer_ary, "idr_layer", "ary");
 	MEMBER_OFFSET_INIT(idr_top, "idr", "top");
+	MEMBER_OFFSET_INIT(idr_cur, "idr", "cur");
 	MEMBER_OFFSET_INIT(ipc_id_ary_p, "ipc_id_ary", "p");
 	MEMBER_OFFSET_INIT(ipc_ids_entries, "ipc_ids", "entries");
 	MEMBER_OFFSET_INIT(ipc_ids_max_id, "ipc_ids", "max_id");
@@ -188,7 +187,10 @@ ipcs_init(void)
 		ipcs_table.shm_f_op_huge_addr = -1;
 	}
 
-	if (BITS32())
+	if (VALID_MEMBER(idr_layer_ary) && 
+	    get_array_length("idr_layer.ary", NULL, 0) > 64)
+		ipcs_table.idr_bits = 8;
+	else if (BITS32())
 		ipcs_table.idr_bits = 5;
 	else if (BITS64())
 		ipcs_table.idr_bits = 6;
@@ -635,7 +637,7 @@ ipc_search_idr(ulong ipc_ids_p, int specified, ulong specified_value, int (*fn)(
 /*
  * search every idr_layer
  */
-static ulong
+ulong
 idr_find(ulong idp, int id)
 {
 	ulong idr_layer_p;
diff --git a/symbols.c b/symbols.c
index bf55319..8ff1430 100644
--- a/symbols.c
+++ b/symbols.c
@@ -10041,6 +10041,8 @@ dump_offset_table(char *spec, ulong makestruct)
 		OFFSET(idr_layers));
 	fprintf(fp, "                       idr_top: %ld\n",
 		OFFSET(idr_top));
+	fprintf(fp, "                       idr_cur: %ld\n",
+		OFFSET(idr_cur));
 	fprintf(fp, "                  ipc_id_ary_p: %ld\n",
 		OFFSET(ipc_id_ary_p));
 	fprintf(fp, "               ipc_ids_entries: %ld\n",