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Iglesias" , Michael Rolnik References: <20240223162202.1936541-1-alex.bennee@linaro.org> <20240223162202.1936541-22-alex.bennee@linaro.org> From: Akihiko Odaki In-Reply-To: <20240223162202.1936541-22-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::434; envelope-from=akihiko.odaki@daynix.com; helo=mail-pf1-x434.google.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=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=no 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 2024/02/24 1:21, 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. As the register set is potentially different for > each vCPU we store a separate set of handles for each vCPU. This will > become more important if we are able to emulate more heterogeneous > systems. > > 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. > v5 > - make reg_handles as per-CPUPluginState variable. > --- > include/qemu/plugin.h | 2 + > include/qemu/qemu-plugin.h | 48 +++++++++++++++++++- > plugins/api.c | 88 ++++++++++++++++++++++++++++++++++++ > plugins/qemu-plugins.symbols | 2 + > 4 files changed, 138 insertions(+), 2 deletions(-) > > diff --git a/include/qemu/plugin.h b/include/qemu/plugin.h > index 0e7b9693d80..64fb425fb0b 100644 > --- a/include/qemu/plugin.h > +++ b/include/qemu/plugin.h > @@ -189,9 +189,11 @@ struct qemu_plugin_insn *qemu_plugin_tb_insn_get(struct qemu_plugin_tb *tb, > /** > * struct CPUPluginState - per-CPU state for plugins > * @event_mask: plugin event bitmap. Modified only via async work. > + * @reg_handles: hash table of register handles. > */ > struct CPUPluginState { > DECLARE_BITMAP(event_mask, QEMU_PLUGIN_EV_MAX); > + GHashTable *reg_handles; > }; > > /** > 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..f6c3ba2366f 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 +413,88 @@ 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 local to each vCPU as there can be slight variations for each > + * vCPU depending on enabled features. We track this in > + * CPUPluginState. > + */ Since we do no longer coalesce registers for different classes, I need to bring my old question back: Why don't you just cast register numbers into pointers and use it as handles? You can even just expose gdb_reg_num with the interface. > + > +struct qemu_plugin_register { > + const char *name; > + int gdb_reg_num; > +}; > + > +/* > + * 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)); > + > + if (!cs->plugin_state->reg_handles) { > + cs->plugin_state->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 = GINT_TO_POINTER(grd->gdb_reg); > + struct qemu_plugin_register *val > + = g_hash_table_lookup(cs->plugin_state->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(cs->plugin_state->reg_handles, key, val); > + } else { > + /* make sure we are not seeing a key clash */ > + g_assert(val->gdb_reg_num == grd->gdb_reg); > + } > + > + /* 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); > +} > 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;