From af5a23a39f544568e79a93250548bef83f9c2fff Mon Sep 17 00:00:00 2001 From: Ciro Santilli Date: Mon, 19 Nov 2018 15:25:44 +0000 Subject: [PATCH] base: add support for GDB's XML architecture definition This is done by implementing the Xfer:features:read packet of the GDB remote protocol. Before this commit, gem5 used the defaults of the GDB client. With this commit, gem5 can inform the client which registers it knows about. This allows in particular to support new registers which an older GDB client does not yet know about. The XML is not implemented in this commit for any arch, and falls back almost exactly to previous behaviour. The only change is that now gem5 replies to the Supported: request which the GDB clients sends at the beginning of the transaction with an empty feature list containing only the mandatory PacketSize= argument. Since the feature list does not contain qXfer:features:read, the GDB client knows that the gem5 server does support the XML format and uses its default registers as before. Change-Id: I5185f28b00e9b9cc8245f4b4262cc324c3d298c1 Reviewed-on: https://gem5-review.googlesource.com/c/15137 Reviewed-by: Andreas Sandberg Maintainer: Andreas Sandberg --- src/base/remote_gdb.cc | 90 +++++++++++++++++++++++++++++++++++++++++- src/base/remote_gdb.hh | 29 ++++++++++++++ 2 files changed, 117 insertions(+), 2 deletions(-) diff --git a/src/base/remote_gdb.cc b/src/base/remote_gdb.cc index 2c54f5b5f..d620665b6 100644 --- a/src/base/remote_gdb.cc +++ b/src/base/remote_gdb.cc @@ -1,4 +1,15 @@ /* + * Copyright (c) 2018 ARM Limited + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * * Copyright 2015 LabWare * Copyright 2014 Google, Inc. * Copyright (c) 2002-2005 The Regents of The University of Michigan @@ -127,6 +138,7 @@ #include #include #include +#include #include #include "arch/vtophys.hh" @@ -966,12 +978,86 @@ BaseRemoteGDB::cmd_mem_w(GdbCommand::Context &ctx) bool BaseRemoteGDB::cmd_query_var(GdbCommand::Context &ctx) { - if (string(ctx.data, ctx.len - 1) != "C") + string s(ctx.data, ctx.len - 1); + string xfer_read_prefix = "Xfer:features:read:"; + if (s.rfind("Supported:", 0) == 0) { + std::ostringstream oss; + // This reply field mandatory. We can receive arbitrarily + // long packets, so we could choose it to be arbitrarily large. + // This is just an arbitrary filler value that seems to work. + oss << "PacketSize=1024"; + for (const auto& feature : availableFeatures()) + oss << ';' << feature; + send(oss.str().c_str()); + } else if (s.rfind(xfer_read_prefix, 0) == 0) { + size_t offset, length; + auto value_string = s.substr(xfer_read_prefix.length()); + auto colon_pos = value_string.find(':'); + auto comma_pos = value_string.find(','); + if (colon_pos == std::string::npos || comma_pos == std::string::npos) + throw CmdError("E00"); + std::string annex; + if (!getXferFeaturesRead(value_string.substr(0, colon_pos), annex)) + throw CmdError("E00"); + try { + offset = std::stoull( + value_string.substr(colon_pos + 1, comma_pos), NULL, 16); + length = std::stoull( + value_string.substr(comma_pos + 1), NULL, 16); + } catch (std::invalid_argument& e) { + throw CmdError("E00"); + } catch (std::out_of_range& e) { + throw CmdError("E00"); + } + std::string encoded; + encodeXferResponse(annex, encoded, offset, length); + send(encoded.c_str()); + } else if (s == "C") { + send("QC0"); + } else { throw Unsupported(); - send("QC0"); + } return true; } +std::vector +BaseRemoteGDB::availableFeatures() const +{ + return {}; +}; + +bool +BaseRemoteGDB::getXferFeaturesRead( + const std::string &annex, std::string &output) +{ + return false; +} + +void +BaseRemoteGDB::encodeBinaryData( + const std::string &unencoded, std::string &encoded) const +{ + for (const char& c : unencoded) { + if (c == '$' || c == '#' || c == '}' || c == '*') { + encoded += '}'; + encoded += c ^ 0x20; + } else { + encoded += c; + } + } +} + +void +BaseRemoteGDB::encodeXferResponse(const std::string &unencoded, + std::string &encoded, size_t offset, size_t unencoded_length) const +{ + if (offset + unencoded_length < unencoded.length()) + encoded += 'm'; + else + encoded += 'l'; + encodeBinaryData(unencoded.substr(offset, unencoded_length), encoded); +} + bool BaseRemoteGDB::cmd_async_step(GdbCommand::Context &ctx) { diff --git a/src/base/remote_gdb.hh b/src/base/remote_gdb.hh index 82a1e15bc..123376cd0 100644 --- a/src/base/remote_gdb.hh +++ b/src/base/remote_gdb.hh @@ -1,4 +1,15 @@ /* + * Copyright (c) 2018 ARM Limited + * + * The license below extends only to copyright in the software and shall + * not be construed as granting a license to any other intellectual + * property including but not limited to intellectual property relating + * to a hardware implementation of the functionality of the software + * licensed hereunder. You may use the software subject to the license + * terms below provided that you ensure that this notice is replicated + * unmodified and in its entirety in all distributions of the software, + * modified or unmodified, in source code or in binary form. + * * Copyright 2015 LabWare * Copyright 2014 Google, Inc. * Copyright (c) 2002-2005 The Regents of The University of Michigan @@ -276,12 +287,30 @@ class BaseRemoteGDB ThreadContext *context() { return tc; } System *system() { return sys; } + void encodeBinaryData(const std::string &unencoded, + std::string &encoded) const; + + void encodeXferResponse(const std::string &unencoded, + std::string &encoded, size_t offset, size_t unencoded_length) const; + // To be implemented by subclasses. virtual bool checkBpLen(size_t len); virtual BaseGdbRegCache *gdbRegs() = 0; virtual bool acc(Addr addr, size_t len) = 0; + + virtual std::vector availableFeatures() const; + + /** + * Get an XML target description. + * + * @param[in] annex the XML filename + * @param[out] output set to the decoded XML + * @return true if the given annex was found + */ + virtual bool getXferFeaturesRead(const std::string &annex, + std::string &output); }; template -- 2.30.2