Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758650Ab1FADKq (ORCPT ); Tue, 31 May 2011 23:10:46 -0400 Received: from mail-yx0-f174.google.com ([209.85.213.174]:36757 "EHLO mail-yx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758628Ab1FADKo (ORCPT ); Tue, 31 May 2011 23:10:44 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=Gz1xdiUm1fFpPJHy1qx1Cg85JGb2WO/sUZdI1QkzdT3KJBEYgSgww1/xfdQ9FCoJnX fshrxGFaSz8FFScwbgl4lWt4rNg8d98f3u3omOPQcVdFcul/7MEr8NygMqiULs+nZsYe 44oANLEmLGVMh0fTvpTf43p/laDVIF1j/uIUk= From: Will Drewry To: linux-kernel@vger.kernel.org Cc: kees.cook@canonical.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@elte.hu, rostedt@goodmis.org, jmorris@namei.org, Will Drewry , Frederic Weisbecker , Ingo Molnar Subject: [PATCH v3 02/13] tracing: split out syscall_trace_enter construction Date: Tue, 31 May 2011 22:10:34 -0500 Message-Id: <1306897845-9393-2-git-send-email-wad@chromium.org> X-Mailer: git-send-email 1.7.0.4 In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6572 Lines: 187 perf appears to be the primary consumer of the CONFIG_FTRACE_SYSCALLS infrastructure. As such, many the helpers target at perf can be split into a peerf-focused helper and a generic CONFIG_FTRACE_SYSCALLS consumer interface. This change splits out syscall_trace_enter construction from perf_syscall_enter for current into two helpers: - ftrace_syscall_enter_state - ftrace_syscall_enter_state_size And adds another helper for completeness: - ftrace_syscall_exit_state_size These helpers allow for shared code between perf ftrace events and any other consumers of CONFIG_FTRACE_SYSCALLS events. The proposed seccomp_filter patches use this code. Signed-off-by: Will Drewry --- include/trace/syscall.h | 4 ++ kernel/trace/trace_syscalls.c | 96 +++++++++++++++++++++++++++++++++++------ 2 files changed, 86 insertions(+), 14 deletions(-) diff --git a/include/trace/syscall.h b/include/trace/syscall.h index 31966a4..242ae04 100644 --- a/include/trace/syscall.h +++ b/include/trace/syscall.h @@ -41,6 +41,10 @@ extern int reg_event_syscall_exit(struct ftrace_event_call *call); extern void unreg_event_syscall_exit(struct ftrace_event_call *call); extern int ftrace_format_syscall(struct ftrace_event_call *call, struct trace_seq *s); +extern int ftrace_syscall_enter_state(u8 *buf, size_t available, + struct trace_entry **entry); +extern size_t ftrace_syscall_enter_state_size(int nb_args); +extern size_t ftrace_syscall_exit_state_size(void); enum print_line_t print_syscall_enter(struct trace_iterator *iter, int flags, struct trace_event *event); enum print_line_t print_syscall_exit(struct trace_iterator *iter, int flags, diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index ee7b5a0..f37f120 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -95,7 +95,7 @@ find_syscall_meta(unsigned long syscall) return NULL; } -static struct syscall_metadata *syscall_nr_to_meta(int nr) +struct syscall_metadata *syscall_nr_to_meta(int nr) { if (!syscalls_metadata || nr >= NR_syscalls || nr < 0) return NULL; @@ -498,7 +498,7 @@ static int sys_perf_refcount_exit; static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) { struct syscall_metadata *sys_data; - struct syscall_trace_enter *rec; + void *buf; struct hlist_head *head; int syscall_nr; int rctx; @@ -513,25 +513,22 @@ static void perf_syscall_enter(void *ignore, struct pt_regs *regs, long id) return; /* get the size after alignment with the u32 buffer size field */ - size = sizeof(unsigned long) * sys_data->nb_args + sizeof(*rec); - size = ALIGN(size + sizeof(u32), sizeof(u64)); - size -= sizeof(u32); + size = ftrace_syscall_enter_state_size(sys_data->nb_args); if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, "perf buffer not large enough")) return; - rec = (struct syscall_trace_enter *)perf_trace_buf_prepare(size, - sys_data->enter_event->event.type, regs, &rctx); - if (!rec) + buf = perf_trace_buf_prepare(size, sys_data->enter_event->event.type, + regs, &rctx); + if (!buf) return; - rec->nr = syscall_nr; - syscall_get_arguments(current, regs, 0, sys_data->nb_args, - (unsigned long *)&rec->args); + /* The only error conditions in this helper are handled above. */ + ftrace_syscall_enter_state(buf, size, NULL); head = this_cpu_ptr(sys_data->enter_event->perf_events); - perf_trace_buf_submit(rec, size, rctx, 0, 1, regs, head); + perf_trace_buf_submit(buf, size, rctx, 0, 1, regs, head); } int perf_sysenter_enable(struct ftrace_event_call *call) @@ -587,8 +584,7 @@ static void perf_syscall_exit(void *ignore, struct pt_regs *regs, long ret) return; /* We can probably do that at build time */ - size = ALIGN(sizeof(*rec) + sizeof(u32), sizeof(u64)); - size -= sizeof(u32); + size = ftrace_syscall_exit_state_size(); /* * Impossible, but be paranoid with the future @@ -688,3 +684,75 @@ static int syscall_exit_register(struct ftrace_event_call *event, } return 0; } + +/* ftrace_syscall_enter_state_size - returns the state size required. + * + * @nb_args: number of system call args expected. + * a negative value implies the maximum allowed. + */ +size_t ftrace_syscall_enter_state_size(int nb_args) +{ + /* syscall_get_arguments only supports up to 6 arguments. */ + int arg_count = (nb_args >= 0 ? nb_args : 6); + size_t size = (sizeof(unsigned long) * arg_count) + + sizeof(struct syscall_trace_enter); + size = ALIGN(size + sizeof(u32), sizeof(u64)); + size -= sizeof(u32); + return size; +} +EXPORT_SYMBOL_GPL(ftrace_syscall_enter_state_size); + +size_t ftrace_syscall_exit_state_size(void) +{ + return ALIGN(sizeof(struct syscall_trace_exit) + sizeof(u32), + sizeof(u64)) - sizeof(u32); +} +EXPORT_SYMBOL_GPL(ftrace_syscall_exit_state_size); + +/* ftrace_syscall_enter_state - build state for filter matching + * + * @buf: buffer to populate with current task state for matching + * @available: size available for use in the buffer. + * @entry: optional pointer to the trace_entry member of the state. + * + * Returns 0 on success and non-zero otherwise. + * If @entry is NULL, it will be ignored. + */ +int ftrace_syscall_enter_state(u8 *buf, size_t available, + struct trace_entry **entry) +{ + struct syscall_trace_enter *sys_enter; + struct syscall_metadata *sys_data; + int size; + int syscall_nr; + struct pt_regs *regs = task_pt_regs(current); + + syscall_nr = syscall_get_nr(current, regs); + if (syscall_nr < 0) + return -EINVAL; + + sys_data = syscall_nr_to_meta(syscall_nr); + if (!sys_data) + return -EINVAL; + + /* Determine the actual size needed. */ + size = sizeof(unsigned long) * sys_data->nb_args + + sizeof(struct syscall_trace_enter); + size = ALIGN(size + sizeof(u32), sizeof(u64)); + size -= sizeof(u32); + + BUG_ON(size > available); + sys_enter = (struct syscall_trace_enter *)buf; + + /* Populating the struct trace_sys_enter is left to the caller, but + * a pointer is returned to encourage opacity. + */ + if (entry) + *entry = &sys_enter->ent; + + sys_enter->nr = syscall_nr; + syscall_get_arguments(current, regs, 0, sys_data->nb_args, + sys_enter->args); + return 0; +} +EXPORT_SYMBOL_GPL(ftrace_syscall_enter_state); -- 1.7.0.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/