[Lldb-commits] [lldb] [lldb] Add QSupported key to report watchpoint types supported (PR #80376)
Jason Molenda via lldb-commits
lldb-commits at lists.llvm.org
Fri Feb 2 11:43:00 PST 2024
https://github.com/jasonmolenda updated https://github.com/llvm/llvm-project/pull/80376
>From 70a518030f2b23ca130a8d0ea667729d7985795c Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmolenda at apple.com>
Date: Thu, 1 Feb 2024 17:46:03 -0800
Subject: [PATCH 1/3] [lldb] Add QSupported key to report watchpoint types
supported
debugserver on arm64 devices can manage both Byte Address Select
watchpoints (1-8 bytes) and MASK watchpoints (8 bytes-2 gigabytes).
This adds a SupportedWatchpointTypes key to the QSupported response
from debugserver with a list of these, so lldb can take full advantage
of them when creating larger regions with a single hardware watchpoint.
Also add documentation for this, and two other lldb extensions, to
the lldb-gdb-remote.txt documentation.
Re-enable TestLargeWatchpoint.py on Darwin systems when testing with
the in-tree built debugserver. I can remove the "in-tree built
debugserver" in the future when this new key is handled by an Xcode
debugserver.
---
lldb/docs/lldb-gdb-remote.txt | 37 +++++++++++++++++++
.../tools/lldb-server/gdbremote_testcase.py | 2 +
.../GDBRemoteCommunicationClient.cpp | 21 +++++++++++
.../gdb-remote/GDBRemoteCommunicationClient.h | 4 ++
.../Process/gdb-remote/ProcessGDBRemote.cpp | 11 +-----
.../large-watchpoint/TestLargeWatchpoint.py | 5 ---
lldb/tools/debugserver/source/RNBRemote.cpp | 30 ++++++++-------
7 files changed, 82 insertions(+), 28 deletions(-)
diff --git a/lldb/docs/lldb-gdb-remote.txt b/lldb/docs/lldb-gdb-remote.txt
index 58269e4c2b688..8db2fbc47b165 100644
--- a/lldb/docs/lldb-gdb-remote.txt
+++ b/lldb/docs/lldb-gdb-remote.txt
@@ -38,7 +38,44 @@ read packet: +
read packet: $OK#9a
send packet: +
+//----------------------------------------------------------------------
+// "QSupported"
+//
+// BRIEF
+// Query the GDB remote server for features it supports
+//
+// PRIORITY TO IMPLEMENT
+// Optional.
+//----------------------------------------------------------------------
+QSupported is a standard GDB Remote Serial Protocol packet, but
+there are several additions to the response that lldb can parse.
+An example exchange:
+
+send packet: qSupported:xmlRegisters=i386,arm,mips,arc;multiprocess+;fork-events+;vfork-events+
+
+read packet: qXfer:features:read+;PacketSize=20000;qEcho+;native-signals+;SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;SupportedWatchpointTypes =aarch64-mask,aarch64-bas;
+
+In this example, three lldb extensions are reported:
+ PacketSize=20000
+ The base16 maximum packet size that the GDB Remote Serial stub
+ can handle.
+ SupportedCompressions=<item,item,...>
+ A list of compression types that the GDB Remote Serial stub can use to
+ compress packets when the QEnableCompression packet is used to request one
+ of them.
+ SupportedWatchpointTypes=<item,item,...>
+ A list of watchpoint types that this GDB Remote Serial stub can manage.
+ Currently defined names are:
+ x86_64 64-bit x86-64 watchpoints
+ (1, 2, 4, 8 byte watchpoints aligned to those amounts)
+ aarch64-bas AArch64 Byte Address Select watchpoints
+ (any number of contiguous bytes within a doubleword)
+ aarch64-mask AArch64 MASK watchpoints
+ (any power-of-2 region of memory from 8 to 2GB, aligned)
+
+lldb will default to sending power-of-2 watchpoints up to a pointer size
+(void*) in the target process if nothing is specified.
//----------------------------------------------------------------------
// "A" - launch args packet
diff --git a/lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py b/lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
index 3341b6e54a3bc..75522158b3221 100644
--- a/lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
+++ b/lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py
@@ -921,6 +921,8 @@ def add_qSupported_packets(self, client_features=[]):
"qSaveCore",
"native-signals",
"QNonStop",
+ "SupportedWatchpointTypes",
+ "SupportedCompressions",
]
def parse_qSupported_response(self, context):
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
index 7bb4498418513..c625adc87cbd4 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
@@ -403,6 +403,22 @@ void GDBRemoteCommunicationClient::GetRemoteQSupported() {
x.split(compressions, ',');
if (!compressions.empty())
MaybeEnableCompression(compressions);
+ } else if (x.consume_front("SupportedWatchpointTypes=")) {
+ llvm::SmallVector<llvm::StringRef, 4> watchpoint_types;
+ x.split(watchpoint_types, ',');
+ m_watchpoint_types =
+ WatchpointHardwareFeature::eWatchpointHardwareFeatureUnknown;
+ for (auto wp_type : watchpoint_types) {
+ if (wp_type == "x86_64")
+ m_watchpoint_types |=
+ WatchpointHardwareFeature::eWatchpointHardwareX86;
+ if (wp_type == "aarch64-mask")
+ m_watchpoint_types |=
+ WatchpointHardwareFeature::eWatchpointHardwareArmMASK;
+ if (wp_type == "aarch64-bas")
+ m_watchpoint_types |=
+ WatchpointHardwareFeature::eWatchpointHardwareArmBAS;
+ }
} else if (x.consume_front("PacketSize=")) {
StringExtractorGDBRemote packet_response(x);
m_max_packet_size =
@@ -1828,6 +1844,11 @@ std::optional<uint32_t> GDBRemoteCommunicationClient::GetWatchpointSlotCount() {
return num;
}
+WatchpointHardwareFeature
+GDBRemoteCommunicationClient::GetSupportedWatchpointTypes() {
+ return m_watchpoint_types;
+}
+
std::optional<bool> GDBRemoteCommunicationClient::GetWatchpointReportedAfter() {
if (m_qHostInfo_is_valid == eLazyBoolCalculate)
GetHostInfo();
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
index 866b0773d86d5..f25b3f9dd1a6d 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
@@ -199,6 +199,8 @@ class GDBRemoteCommunicationClient : public GDBRemoteClientBase {
std::optional<bool> GetWatchpointReportedAfter();
+ lldb::WatchpointHardwareFeature GetSupportedWatchpointTypes();
+
const ArchSpec &GetHostArchitecture();
std::chrono::seconds GetHostDefaultPacketTimeout();
@@ -581,6 +583,8 @@ class GDBRemoteCommunicationClient : public GDBRemoteClientBase {
lldb::tid_t m_curr_tid_run = LLDB_INVALID_THREAD_ID;
uint32_t m_num_supported_hardware_watchpoints = 0;
+ lldb::WatchpointHardwareFeature m_watchpoint_types =
+ lldb::WatchpointHardwareFeature::eWatchpointHardwareFeatureUnknown;
uint32_t m_low_mem_addressing_bits = 0;
uint32_t m_high_mem_addressing_bits = 0;
diff --git a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
index 4e3447e767c35..629b191f3117a 100644
--- a/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -3156,16 +3156,7 @@ Status ProcessGDBRemote::EnableWatchpoint(WatchpointSP wp_sp, bool notify) {
ArchSpec target_arch = GetTarget().GetArchitecture();
WatchpointHardwareFeature supported_features =
- eWatchpointHardwareFeatureUnknown;
-
- // LWP_TODO: enable MASK watchpoint for arm64 debugserver
- // when it reports that it supports them.
- if (target_arch.GetTriple().getOS() == llvm::Triple::MacOSX &&
- target_arch.GetTriple().getArch() == llvm::Triple::aarch64) {
-#if 0
- supported_features |= eWatchpointHardwareArmMASK;
-#endif
- }
+ m_gdb_comm.GetSupportedWatchpointTypes();
std::vector<WatchpointResourceSP> resources =
WatchpointAlgorithms::AtomizeWatchpointRequest(
diff --git a/lldb/test/API/functionalities/watchpoint/large-watchpoint/TestLargeWatchpoint.py b/lldb/test/API/functionalities/watchpoint/large-watchpoint/TestLargeWatchpoint.py
index f7ceb47c0b615..c5e161497e628 100644
--- a/lldb/test/API/functionalities/watchpoint/large-watchpoint/TestLargeWatchpoint.py
+++ b/lldb/test/API/functionalities/watchpoint/large-watchpoint/TestLargeWatchpoint.py
@@ -25,11 +25,6 @@ def continue_and_report_stop_reason(self, process, iter_str):
@skipIf(archs=no_match(["arm64", "arm64e", "aarch64"]))
@skipUnlessDarwin
- # LWP_TODO: until debugserver advertises that it supports
- # MASK watchpoints, this test can't be enabled, lldb won't
- # try to send watchpoints larger than 8 bytes.
- @skipIfDarwin
-
# debugserver only gained the ability to watch larger regions
# with this patch.
@skipIfOutOfTreeDebugserver
diff --git a/lldb/tools/debugserver/source/RNBRemote.cpp b/lldb/tools/debugserver/source/RNBRemote.cpp
index 224ed033fc421..20384920823d2 100644
--- a/lldb/tools/debugserver/source/RNBRemote.cpp
+++ b/lldb/tools/debugserver/source/RNBRemote.cpp
@@ -3557,10 +3557,10 @@ static bool GetProcessNameFrom_vAttach(const char *&p,
rnb_err_t RNBRemote::HandlePacket_qSupported(const char *p) {
uint32_t max_packet_size = 128 * 1024; // 128KBytes is a reasonable max packet
// size--debugger can always use less
- char buf[256];
- snprintf(buf, sizeof(buf),
- "qXfer:features:read+;PacketSize=%x;qEcho+;native-signals+",
- max_packet_size);
+ std::stringstream reply;
+ reply << "qXfer:features:read+;PacketSize=" << std::hex << max_packet_size
+ << ";";
+ reply << "qEcho+;native-signals+;";
bool enable_compression = false;
(void)enable_compression;
@@ -3574,15 +3574,19 @@ rnb_err_t RNBRemote::HandlePacket_qSupported(const char *p) {
#endif
if (enable_compression) {
- strcat(buf, ";SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;"
- "DefaultCompressionMinSize=");
- char numbuf[16];
- snprintf(numbuf, sizeof(numbuf), "%zu", m_compression_minsize);
- numbuf[sizeof(numbuf) - 1] = '\0';
- strcat(buf, numbuf);
- }
-
- return SendPacket(buf);
+ reply << "SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;";
+ reply << "DefaultCompressionMinSize=" << std::dec << m_compression_minsize
+ << ";";
+ }
+
+#if (defined(__arm64__) || defined(__aarch64__))
+ reply << "SupportedWatchpointTypes=aarch64-mask,aarch64-bas;";
+#endif
+#if defined(__x86_64__)
+ reply << "SupportedWatchpointTypes=x86_64;";
+#endif
+
+ return SendPacket(reply.str().c_str());
}
static bool process_does_not_exist (nub_process_t pid) {
>From 17e0b7b06cd0cf2fe4f9e6c1f338afb536ec7796 Mon Sep 17 00:00:00 2001
From: Jason Molenda <jmolenda at apple.com>
Date: Thu, 1 Feb 2024 19:10:53 -0800
Subject: [PATCH 2/3] Clarify 'size of pointer' language.
---
lldb/docs/lldb-gdb-remote.txt | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/lldb/docs/lldb-gdb-remote.txt b/lldb/docs/lldb-gdb-remote.txt
index 8db2fbc47b165..a291f6bd150eb 100644
--- a/lldb/docs/lldb-gdb-remote.txt
+++ b/lldb/docs/lldb-gdb-remote.txt
@@ -74,8 +74,8 @@ In this example, three lldb extensions are reported:
aarch64-mask AArch64 MASK watchpoints
(any power-of-2 region of memory from 8 to 2GB, aligned)
-lldb will default to sending power-of-2 watchpoints up to a pointer size
-(void*) in the target process if nothing is specified.
+lldb will default to sending power-of-2 watchpoints up to a pointer size,
+`sizeof(void*)`, in the target process if nothing is specified.
//----------------------------------------------------------------------
// "A" - launch args packet
>From f2bf59ba6d13598babfaf31b2470ffa233f92fc6 Mon Sep 17 00:00:00 2001
From: Jason Molenda <jason at molenda.com>
Date: Fri, 2 Feb 2024 11:40:52 -0800
Subject: [PATCH 3/3] Address David's initial feedback comments
---
lldb/docs/lldb-gdb-remote.txt | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/lldb/docs/lldb-gdb-remote.txt b/lldb/docs/lldb-gdb-remote.txt
index a291f6bd150eb..f668ec0ce150c 100644
--- a/lldb/docs/lldb-gdb-remote.txt
+++ b/lldb/docs/lldb-gdb-remote.txt
@@ -54,18 +54,17 @@ An example exchange:
send packet: qSupported:xmlRegisters=i386,arm,mips,arc;multiprocess+;fork-events+;vfork-events+
-read packet: qXfer:features:read+;PacketSize=20000;qEcho+;native-signals+;SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;SupportedWatchpointTypes =aarch64-mask,aarch64-bas;
+read packet: qXfer:features:read+;PacketSize=20000;qEcho+;native-signals+;SupportedCompressions=lzfse,zlib-deflate,lz4,lzma;SupportedWatchpointTypes=aarch64-mask,aarch64-bas;
In this example, three lldb extensions are reported:
+
PacketSize=20000
- The base16 maximum packet size that the GDB Remote Serial stub
- can handle.
+ The base16 maximum packet size that the stub can handle.
SupportedCompressions=<item,item,...>
- A list of compression types that the GDB Remote Serial stub can use to
- compress packets when the QEnableCompression packet is used to request one
- of them.
+ A list of compression types that the stub can use to compress packets
+ when the QEnableCompression packet is used to request one of them.
SupportedWatchpointTypes=<item,item,...>
- A list of watchpoint types that this GDB Remote Serial stub can manage.
+ A list of watchpoint types that this stub can manage.
Currently defined names are:
x86_64 64-bit x86-64 watchpoints
(1, 2, 4, 8 byte watchpoints aligned to those amounts)
@@ -73,9 +72,9 @@ In this example, three lldb extensions are reported:
(any number of contiguous bytes within a doubleword)
aarch64-mask AArch64 MASK watchpoints
(any power-of-2 region of memory from 8 to 2GB, aligned)
-
-lldb will default to sending power-of-2 watchpoints up to a pointer size,
-`sizeof(void*)`, in the target process if nothing is specified.
+ If nothing is specified, lldb will default to sending power-of-2
+ watchpoints, up to a pointer size, `sizeof(void*)`, a reasonable
+ baseline assumption.
//----------------------------------------------------------------------
// "A" - launch args packet
More information about the lldb-commits
mailing list