Re: [PATCH 1/2] watchpoint-reuse-slot.exp: skip some tests on targets have different wp and bp registers

[Yao Qi <qiyaoltc@gmail.com>]

Pedro Alves <palves@redhat.com> writes:

> Yes, that makes sense.
>
>> 
>> The inner loop of test has two parts, "base + 0" and "base + 1",
>> 
>> 		    append prefix "$cmd1 x $cmd2: "
>> 		    with_test_prefix "$prefix: width $width, iter $x" {
>> 			with_test_prefix "base + 0" {
>> 			    watch_command $cmd1 $x 0 $width
>> 			    stepi
>> 			    gdb_test_no_output "delete \$bpnum"
>> 			}
>> 			with_test_prefix "base + 1" {
>> 			    watch_command $cmd2 $x 1 $width
>> 			    stepi
>> 			    gdb_test_no_output "delete \$bpnum"
>> 			}
>> 		    }
>> 
>> if we skip "base + 1" part, do we skip "base + 0" too? if not, prefix in
>> test summary "$cmd1 x $cmd2: " doesn't reflect the fact.
>
> I think skipping both is fine.

OK, how about the patch below?

-- 
Yao (齐尧)


From: Yao Qi <yao.qi@linaro.org>
Subject: [PATCH] watchpoint-reuse-slot.exp: skip setting HW breakpoints on some address

We see some fails in watchpoint-reuse-slot.exp on aarch64-linux, because
it sets some HW breakpoint on some address doesn't meet the alignment
requirements by kernel, kernel will reject the
ptrace (PTRACE_SETHBPREGS) call, and some fails are caused, for example:

(gdb) PASS: gdb.base/watchpoint-reuse-slot.exp: always-inserted off: watch x hbreak: : width 1, iter 0: base + 0: delete $bpnum
hbreak *(buf.byte + 0 + 1)^M
Hardware assisted breakpoint 80 at 0x410a61^M
(gdb) PASS: gdb.base/watchpoint-reuse-slot.exp: always-inserted off: watch x hbreak: : width 1, iter 0: base + 1: hbreak *(buf.byte + 0 + 1)
stepi^M
Warning:^M
Cannot insert hardware breakpoint 80.^M
Could not insert hardware breakpoints:^M
You may have requested too many hardware breakpoints/watchpoints.^M
^M
(gdb) FAIL: gdb.base/watchpoint-reuse-slot.exp: always-inserted off: watch x hbreak: : width 1, iter 0: base + 1: stepi advanced

hbreak *(buf.byte + 0 + 1)^M
Hardware assisted breakpoint 440 at 0x410a61^M
Warning:^M
Cannot insert hardware breakpoint 440.^M
Could not insert hardware breakpoints:^M
You may have requested too many hardware breakpoints/watchpoints.^M
^M
(gdb) FAIL: gdb.base/watchpoint-reuse-slot.exp: always-inserted on: watch x hbreak: : width 1, iter 0: base + 1: hbreak *(buf.byte + 0 + 1)

This patch is to skip some tests by checking proc valid_addr_p.
We can handle other targets in valid_addr_p too.

gdb/testsuite:

2015-03-16  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/watchpoint-reuse-slot.exp: Get the address of
	buf.byte.
	(valid_addr_p): New proc.
	(top level): Skip tests if valid_addr_p returns false for
	$cmd1 or $cmd2.

diff --git a/gdb/testsuite/gdb.base/watchpoint-reuse-slot.exp b/gdb/testsuite/gdb.base/watchpoint-reuse-slot.exp
index 844bf3a..28839fe 100644
--- a/gdb/testsuite/gdb.base/watchpoint-reuse-slot.exp
+++ b/gdb/testsuite/gdb.base/watchpoint-reuse-slot.exp
@@ -133,6 +133,39 @@ delete_breakpoints
 
 set cur_addr [get_pc]
 
+# The addrss of buf.byte
+set buf_byte_addr ""
+set test "get address of buf.byte"
+gdb_test_multiple "p /d &buf.byte" "$test" {
+    -re " = ($decimal).*$gdb_prompt $" {
+	set buf_byte_addr $expect_out(1,string)
+	pass "$test"
+    }
+}
+
+# Return true if the memory range [buf.byte + OFFSET, +WIDTH] can be
+# monitored by CMD, otherwise return false.
+
+proc  valid_addr_p {cmd offset width} {
+    global buf_byte_addr
+
+    set addr [expr $buf_byte_addr + $offset]
+    if { [istarget "aarch64*-*-linux*"] } {
+	# aarch64 linux kernel accepts 4-byte aligned address for
+	# hardware breakpoint and 8-byte aligned address for hardware
+	# watchpoint.  However, GDB and GDBserver use one or more
+	# watchpoint registers to represent the whole unaligned region
+	# while each individual is properly aligned.
+	if {$cmd == "hbreak" } {
+	    if { [expr $addr % 4] != 0 } {
+		return 0
+	    }
+	}
+    }
+
+    return 1
+}
+
 # Watch WIDTH bytes at BASE + OFFSET.  CMD specifices the specific
 # type of watchpoint to use.  If CMD is "hbreak", WIDTH is ignored.
 
@@ -172,6 +205,15 @@ foreach always_inserted {"off" "on" } {
 		}
 
 		for {set x 0} {$x < 4} {incr x} {
+
+		    if { ![valid_addr_p $cmd1 $x $width]
+			 || ![valid_addr_p $cmd2 $x+1 $width] } {
+			# Skip tests if requested address or length
+			# of breakpoint or watchpoint don't meet
+			# target or kernel requirements.
+			continue
+		    }
+
 		    set prefix "always-inserted $always_inserted: "
 		    append prefix "$cmd1 x $cmd2: "
 		    with_test_prefix "$prefix: width $width, iter $x" {