From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 582C4C48BC3 for ; Sat, 17 Feb 2024 08:02:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rbFdo-0008KQ-KO; Sat, 17 Feb 2024 03:01:45 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rbFdf-0008JD-BS for qemu-devel@nongnu.org; Sat, 17 Feb 2024 03:01:36 -0500 Received: from mail-pl1-x634.google.com ([2607:f8b0:4864:20::634]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1rbFda-0003Iz-Ar for qemu-devel@nongnu.org; Sat, 17 Feb 2024 03:01:34 -0500 Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-1d70b0e521eso23252585ad.1 for ; Sat, 17 Feb 2024 00:01:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=daynix-com.20230601.gappssmtp.com; s=20230601; t=1708156887; x=1708761687; darn=nongnu.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=/oUa/m3j6N+SGoUDbXChizcm11JI1QB5HKNL+fidvys=; b=UtQbOwPEf4XBnxq3RAn25064IV9/georDQtEetwiop3DbzBN/nl8lvFmuJqi9NOATb RalTdJri08T5Y9ddme5lOFLFqXi6VzCxNUITKtXn734jPT2QXTuVXCjYIMEN+zhYlPy8 MnV0Hh1gaCYKyQ89P71Jelk5lDtIXoOskqro7vbO6X6C1q4XmkhT9wgpA0Bqv2J1JA+D deYX48UhmqB58SxvdRsS8DUOdXAnnhW7QHbLfYcD9Bg4cpQMPlPo78ug/3QtvAHx8/gl 2l4yWZH3tolikVRc59gmjT8Hp1cIUEqxGjcBxPtgMM1uDX1c9H6YxU2WDYAfiuKTBJwY 6qYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708156887; x=1708761687; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=/oUa/m3j6N+SGoUDbXChizcm11JI1QB5HKNL+fidvys=; b=ej+tlAuAM2NsZvukUTfBVdx6r0NNNBneegRZBpZxpPN+QXHK9PXakL0zr1e+cwd85F FmPZWgnIlgCj7n+L1nAjU9HxLXUkOz6pk2cmLtbIiXTPHs543ZYa+54syTwIN8s7f7OQ AU479ZxZV35dE0CDIxDph6qFoUyB6k5+Obyz2bsSv5F7QuOHkv0HxT/ukT9Twdhf9KL0 xxDYO2K9NMQxdM7ahlhGagx4tLBDVl1NALSpXT4Vx4KoQ/TCUX4prEcrA4AcKJVDkWsB ncSF4pMo7hUWRaajO5kafO6lHxOTKS2xTc6AxTyWFP81NNwbHw+ZIle+6XGWP5BFwCTc 5Yjg== X-Forwarded-Encrypted: i=1; AJvYcCXM5TRZN4DuOyCYgcBqeLNvjpMsjlo7LNLk/gfpE6HTfmOMRhLZC6VIfqBuLlvNrQCSRqnti4wHZdsplmx/6OlfLktxrC0= X-Gm-Message-State: AOJu0YwoDCFweLRAPvq3tUuy/Tw70ZkWQGZ4xdHEjzr9Pw82WJW4+kx4 SzFfV8sNqBtVZyMW+tA2OAsicRXeWtJ9Zq5iZpmcyewzwuoNuU0/FGDF3ZaZJcU= X-Google-Smtp-Source: AGHT+IFtKdrqAg/YHzurC8U9rB59bhu0467F2B4etNMpR1lrYn8ivjuQfP/Oz0WeOewEOxr5YwOR5A== X-Received: by 2002:a17:903:1c9:b0:1db:d42f:fdb9 with SMTP id e9-20020a17090301c900b001dbd42ffdb9mr40139plh.40.1708156887288; Sat, 17 Feb 2024 00:01:27 -0800 (PST) Received: from [157.82.200.138] ([157.82.200.138]) by smtp.gmail.com with ESMTPSA id km14-20020a17090327ce00b001db535f1549sm936241plb.235.2024.02.17.00.01.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 17 Feb 2024 00:01:26 -0800 (PST) Message-ID: Date: Sat, 17 Feb 2024 17:01:19 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 18/23] plugins: add an API to read registers To: =?UTF-8?Q?Alex_Benn=C3=A9e?= , qemu-devel@nongnu.org Cc: Yoshinori Sato , David Hildenbrand , Weiwei Li , Richard Henderson , Michael Rolnik , Ilya Leoshkevich , Peter Maydell , qemu-ppc@nongnu.org, Paolo Bonzini , qemu-riscv@nongnu.org, Cleber Rosa , Thomas Huth , Song Gao , qemu-arm@nongnu.org, Pierrick Bouvier , John Snow , =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Nicholas Piggin , qemu-s390x@nongnu.org, Laurent Vivier , "Edgar E. Iglesias" , Daniel Henrique Barboza , Yanan Wang , Palmer Dabbelt , Marcel Apfelbaum , Brian Cain , Mahmoud Mandour , Alexandre Iooss , Bin Meng , =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , Daniel Henrique Barboza , Eduardo Habkost , Alistair Francis , Liu Zhiwei References: <20240216163025.424857-1-alex.bennee@linaro.org> <20240216163025.424857-19-alex.bennee@linaro.org> Content-Language: en-US From: Akihiko Odaki In-Reply-To: <20240216163025.424857-19-alex.bennee@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: none client-ip=2607:f8b0:4864:20::634; envelope-from=akihiko.odaki@daynix.com; helo=mail-pl1-x634.google.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_NONE=0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2024/02/17 1:30, Alex Bennée wrote: > We can only request a list of registers once the vCPU has been > initialised so the user needs to use either call the get function on > vCPU initialisation or during the translation phase. > > We don't expose the reg number to the plugin instead hiding it behind > an opaque handle. This allows for a bit of future proofing should the > internals need to be changed while also being hashed against the > CPUClass so we can handle different register sets per-vCPU in > hetrogenous situations. > > Having an internal state within the plugins also allows us to expand > the interface in future (for example providing callbacks on register > change if the translator can track changes). > > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1706 > Cc: Akihiko Odaki > Message-Id: <20240103173349.398526-39-alex.bennee@linaro.org> > Based-on: <20231025093128.33116-18-akihiko.odaki@daynix.com> > Signed-off-by: Alex Bennée > Reviewed-by: Pierrick Bouvier > > --- > v4 > - the get/read_registers functions are now implicitly for current > vCPU only to accidental cpu != current_cpu uses. > --- > include/qemu/qemu-plugin.h | 48 +++++++++++++++- > plugins/api.c | 107 +++++++++++++++++++++++++++++++++++ > plugins/qemu-plugins.symbols | 2 + > 3 files changed, 155 insertions(+), 2 deletions(-) > > diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h > index 93981f8f89f..3b6b18058d2 100644 > --- a/include/qemu/qemu-plugin.h > +++ b/include/qemu/qemu-plugin.h > @@ -11,6 +11,7 @@ > #ifndef QEMU_QEMU_PLUGIN_H > #define QEMU_QEMU_PLUGIN_H > > +#include > #include > #include > #include > @@ -229,8 +230,8 @@ struct qemu_plugin_insn; > * @QEMU_PLUGIN_CB_R_REGS: callback reads the CPU's regs > * @QEMU_PLUGIN_CB_RW_REGS: callback reads and writes the CPU's regs > * > - * Note: currently unused, plugins cannot read or change system > - * register state. > + * Note: currently QEMU_PLUGIN_CB_RW_REGS is unused, plugins cannot change > + * system register state. > */ > enum qemu_plugin_cb_flags { > QEMU_PLUGIN_CB_NO_REGS, > @@ -707,4 +708,47 @@ uint64_t qemu_plugin_end_code(void); > QEMU_PLUGIN_API > uint64_t qemu_plugin_entry_code(void); > > +/** struct qemu_plugin_register - Opaque handle for register access */ > +struct qemu_plugin_register; > + > +/** > + * typedef qemu_plugin_reg_descriptor - register descriptions > + * > + * @handle: opaque handle for retrieving value with qemu_plugin_read_register > + * @name: register name > + * @feature: optional feature descriptor, can be NULL > + */ > +typedef struct { > + struct qemu_plugin_register *handle; > + const char *name; > + const char *feature; > +} qemu_plugin_reg_descriptor; > + > +/** > + * qemu_plugin_get_registers() - return register list for current vCPU > + * > + * Returns a GArray of qemu_plugin_reg_descriptor or NULL. Caller > + * frees the array (but not the const strings). > + * > + * Should be used from a qemu_plugin_register_vcpu_init_cb() callback > + * after the vCPU is initialised, i.e. in the vCPU context. > + */ > +GArray *qemu_plugin_get_registers(void); > + > +/** > + * qemu_plugin_read_register() - read register for current vCPU > + * > + * @handle: a @qemu_plugin_reg_handle handle > + * @buf: A GByteArray for the data owned by the plugin > + * > + * This function is only available in a context that register read access is > + * explicitly requested via the QEMU_PLUGIN_CB_R_REGS flag. > + * > + * Returns the size of the read register. The content of @buf is in target byte > + * order. On failure returns -1 > + */ > +int qemu_plugin_read_register(struct qemu_plugin_register *handle, > + GByteArray *buf); > + > + > #endif /* QEMU_QEMU_PLUGIN_H */ > diff --git a/plugins/api.c b/plugins/api.c > index 54df72c1c00..483f04e85e4 100644 > --- a/plugins/api.c > +++ b/plugins/api.c > @@ -8,6 +8,7 @@ > * > * qemu_plugin_tb > * qemu_plugin_insn > + * qemu_plugin_register > * > * Which can then be passed back into the API to do additional things. > * As such all the public functions in here are exported in > @@ -35,10 +36,12 @@ > */ > > #include "qemu/osdep.h" > +#include "qemu/main-loop.h" > #include "qemu/plugin.h" > #include "qemu/log.h" > #include "tcg/tcg.h" > #include "exec/exec-all.h" > +#include "exec/gdbstub.h" > #include "exec/ram_addr.h" > #include "disas/disas.h" > #include "plugin.h" > @@ -410,3 +413,107 @@ uint64_t qemu_plugin_entry_code(void) > #endif > return entry; > } > + > +/* > + * Register handles > + * > + * The plugin infrastructure keeps hold of these internal data > + * structures which are presented to plugins as opaque handles. They > + * are global to the system and therefor additions to the hash table > + * must be protected by the @reg_handle_lock. > + * > + * In order to future proof for up-coming heterogeneous work we want > + * different entries for each CPU type while sharing them in the > + * common case of multiple cores of the same type. > + */ > + > +static QemuMutex reg_handle_lock; > + > +struct qemu_plugin_register { > + const char *name; > + int gdb_reg_num; > +}; > + > +static GHashTable *reg_handles; /* hash table of PluginReg */ > + > +/* Generate a stable key - would xxhash be overkill? */ > +static gpointer cpu_plus_reg_to_key(CPUState *cs, int gdb_regnum) > +{ > + uintptr_t key = (uintptr_t) cs->cc; > + key ^= gdb_regnum; > + return GUINT_TO_POINTER(key); > +} I have pointed out this is theoretically prone to collisions and unsafe. > + > +/* > + * Create register handles. > + * > + * We need to create a handle for each register so the plugin > + * infrastructure can call gdbstub to read a register. We also > + * construct a result array with those handles and some ancillary data > + * the plugin might find useful. > + */ > + > +static GArray *create_register_handles(CPUState *cs, GArray *gdbstub_regs) > +{ > + GArray *find_data = g_array_new(true, true, > + sizeof(qemu_plugin_reg_descriptor)); > + > + WITH_QEMU_LOCK_GUARD(®_handle_lock) { > + > + if (!reg_handles) { > + reg_handles = g_hash_table_new(g_direct_hash, g_direct_equal); > + } > + > + for (int i = 0; i < gdbstub_regs->len; i++) { > + GDBRegDesc *grd = &g_array_index(gdbstub_regs, GDBRegDesc, i); > + gpointer key = cpu_plus_reg_to_key(cs, grd->gdb_reg); > + struct qemu_plugin_register *val = g_hash_table_lookup(reg_handles, > + key); > + > + /* skip "un-named" regs */ > + if (!grd->name) { > + continue; > + } > + > + /* Doesn't exist, create one */ > + if (!val) { > + val = g_new0(struct qemu_plugin_register, 1); > + val->gdb_reg_num = grd->gdb_reg; > + val->name = g_intern_string(grd->name); > + > + g_hash_table_insert(reg_handles, key, val); > + } > + > + /* Create a record for the plugin */ > + qemu_plugin_reg_descriptor desc = { > + .handle = val, > + .name = val->name, > + .feature = g_intern_string(grd->feature_name) > + }; > + g_array_append_val(find_data, desc); > + } > + } > + > + return find_data; > +} > + > +GArray *qemu_plugin_get_registers(void) > +{ > + g_assert(current_cpu); > + > + g_autoptr(GArray) regs = gdb_get_register_list(current_cpu); > + return regs->len ? create_register_handles(current_cpu, regs) : NULL; > +} > + > +int qemu_plugin_read_register(struct qemu_plugin_register *reg, GByteArray *buf) > +{ > + g_assert(current_cpu); > + > + return gdb_read_register(current_cpu, buf, reg->gdb_reg_num); > +} > + > +static void __attribute__((__constructor__)) qemu_api_init(void) > +{ > + qemu_mutex_init(®_handle_lock); > + > +} > diff --git a/plugins/qemu-plugins.symbols b/plugins/qemu-plugins.symbols > index adb67608598..27fe97239be 100644 > --- a/plugins/qemu-plugins.symbols > +++ b/plugins/qemu-plugins.symbols > @@ -3,6 +3,7 @@ > qemu_plugin_end_code; > qemu_plugin_entry_code; > qemu_plugin_get_hwaddr; > + qemu_plugin_get_registers; > qemu_plugin_hwaddr_device_name; > qemu_plugin_hwaddr_is_io; > qemu_plugin_hwaddr_phys_addr; > @@ -19,6 +20,7 @@ > qemu_plugin_num_vcpus; > qemu_plugin_outs; > qemu_plugin_path_to_binary; > + qemu_plugin_read_register; > qemu_plugin_register_atexit_cb; > qemu_plugin_register_flush_cb; > qemu_plugin_register_vcpu_exit_cb;