From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751820Ab2GSMw3 (ORCPT ); Thu, 19 Jul 2012 08:52:29 -0400 Received: from hrndva-omtalb.mail.rr.com ([71.74.56.122]:27924 "EHLO hrndva-omtalb.mail.rr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751188Ab2GSMw1 (ORCPT ); Thu, 19 Jul 2012 08:52:27 -0400 X-Authority-Analysis: v=2.0 cv=ZuBv2qHG c=1 sm=0 a=s5Htg7xnQOKvHEu9STBOug==:17 a=OpT9cpI26MMA:10 a=XNQpylE1qVEA:10 a=5SG0PmZfjMsA:10 a=Q9fys5e9bTEA:10 a=meVymXHHAAAA:8 a=ayC55rCoAAAA:8 a=3nbZYyFuAAAA:8 a=or9r430RNDqotrzzxisA:9 a=PUjeQqilurYA:10 a=EvKJbDF4Ut8A:10 a=s5Htg7xnQOKvHEu9STBOug==:117 X-Cloudmark-Score: 0 X-Originating-IP: 72.230.195.127 Message-ID: <1342702344.12353.16.camel@gandalf.stny.rr.com> Subject: Re: Re: [RFC][PATCH 2/4 v4] ftrace/x86: Add save_regs for i386 function calls From: Steven Rostedt To: Masami Hiramatsu Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Frederic Weisbecker , "H. Peter Anvin" , yrl.pp-manager.tt@hitachi.com Date: Thu, 19 Jul 2012 08:52:24 -0400 In-Reply-To: <50076ED9.3000100@hitachi.com> References: <20120711195048.885039013@goodmis.org> <20120711195745.379060003@goodmis.org> <4FFEC58E.5070202@hitachi.com> <1342205273.30075.19.camel@gandalf.stny.rr.com> <1342627145.11900.7.camel@gandalf.stny.rr.com> <50076ED9.3000100@hitachi.com> Content-Type: text/plain; charset="ISO-8859-15" X-Mailer: Evolution 3.4.3-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2012-07-19 at 11:20 +0900, Masami Hiramatsu wrote: > (2012/07/19 0:59), Steven Rostedt wrote: > > On Fri, 2012-07-13 at 14:47 -0400, Steven Rostedt wrote: > > > > Masami, can you give your Reviewed-by tag for this version? Or is there > > something else needing to be fixed? > > No, that is OK for me. I've just missed that... > > Reviewed-by: Masami Hiramatsu > > Thank you! > Thanks! Except I have one more version. Someone offlist gave me some ideas. Here's the diff from the previous patch. diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 46caa56..ca5a146 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -1169,10 +1169,9 @@ ENTRY(ftrace_regs_caller) movl $__KERNEL_CS,13*4(%esp) movl 12*4(%esp), %eax /* Load ip (1st parameter) */ - movl 0x4(%ebp), %edx /* Load parent ip (2cd parameter) */ - lea (%esp), %ecx - pushl %ecx /* Save pt_regs as 4th parameter */ + movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ + pushl %esp /* Save pt_regs as 4th parameter */ GLOBAL(ftrace_regs_call) call ftrace_stub @@ -1195,8 +1194,8 @@ GLOBAL(ftrace_regs_call) popl %es popl %fs popl %gs - addl $8, %esp /* Skip orig_ax and ip */ - popf /* Pop flags at end (no addl to corrupt flags) */ + lea 8(%esp), %esp /* Skip orig_ax and ip */ + popf /* Pop flags at end */ jmp ftrace_ret ftrace_restore_flags: Because we no longer have that 4 byte offset on the stack when we need to load the 4th parameter, we can just load the current stack pointer into the stack (pushl %esp), without the save to %ecx step. also, because lea is faster than add (and doesn't even modify flags), I changed the last part to use lea instead of addl. Can you give your reviewed-by tag for this too? I'd like to push this out today so we can still make 3.6. Thanks! -- Steve here's the full patch: diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h index a847501..a6cae0c 100644 --- a/arch/x86/include/asm/ftrace.h +++ b/arch/x86/include/asm/ftrace.h @@ -40,10 +40,8 @@ #ifdef CONFIG_DYNAMIC_FTRACE #define ARCH_SUPPORTS_FTRACE_OPS 1 -#ifdef CONFIG_X86_64 #define ARCH_SUPPORTS_FTRACE_SAVE_REGS #endif -#endif #ifndef __ASSEMBLY__ extern void mcount(void); diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 5da11d1..ca5a146 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -1123,6 +1123,7 @@ ftrace_call: popl %edx popl %ecx popl %eax +ftrace_ret: #ifdef CONFIG_FUNCTION_GRAPH_TRACER .globl ftrace_graph_call ftrace_graph_call: @@ -1134,6 +1135,72 @@ ftrace_stub: ret END(ftrace_caller) +ENTRY(ftrace_regs_caller) + pushf /* push flags before compare (in cs location) */ + cmpl $0, function_trace_stop + jne ftrace_restore_flags + + /* + * i386 does not save SS and ESP when coming from kernel. + * Instead, to get sp, ®s->sp is used (see ptrace.h). + * Unfortunately, that means eflags must be at the same location + * as the current return ip is. We move the return ip into the + * ip location, and move flags into the return ip location. + */ + pushl 4(%esp) /* save return ip into ip slot */ + subl $MCOUNT_INSN_SIZE, (%esp) /* Adjust ip */ + + pushl $0 /* Load 0 into orig_ax */ + pushl %gs + pushl %fs + pushl %es + pushl %ds + pushl %eax + pushl %ebp + pushl %edi + pushl %esi + pushl %edx + pushl %ecx + pushl %ebx + + movl 13*4(%esp), %eax /* Get the saved flags */ + movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */ + /* clobbering return ip */ + movl $__KERNEL_CS,13*4(%esp) + + movl 12*4(%esp), %eax /* Load ip (1st parameter) */ + movl 0x4(%ebp), %edx /* Load parent ip (2nd parameter) */ + leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */ + pushl %esp /* Save pt_regs as 4th parameter */ + +GLOBAL(ftrace_regs_call) + call ftrace_stub + + addl $4, %esp /* Skip pt_regs */ + movl 14*4(%esp), %eax /* Move flags back into cs */ + movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */ + movl 12*4(%esp), %eax /* Get return ip from regs->ip */ + addl $MCOUNT_INSN_SIZE, %eax + movl %eax, 14*4(%esp) /* Put return ip back for ret */ + + popl %ebx + popl %ecx + popl %edx + popl %esi + popl %edi + popl %ebp + popl %eax + popl %ds + popl %es + popl %fs + popl %gs + lea 8(%esp), %esp /* Skip orig_ax and ip */ + popf /* Pop flags at end */ + jmp ftrace_ret + +ftrace_restore_flags: + popf + jmp ftrace_stub #else /* ! CONFIG_DYNAMIC_FTRACE */ ENTRY(mcount) diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c index b90eb1a..1d41402 100644 --- a/arch/x86/kernel/ftrace.c +++ b/arch/x86/kernel/ftrace.c @@ -206,7 +206,6 @@ static int ftrace_modify_code(unsigned long ip, unsigned const char *old_code, unsigned const char *new_code); -#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS /* * Should never be called: * As it is only called by __ftrace_replace_code() which is called by @@ -221,7 +220,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, WARN_ON(1); return -EINVAL; } -#endif int ftrace_update_ftrace_func(ftrace_func_t func) { @@ -237,7 +235,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ret = ftrace_modify_code(ip, old, new); -#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS /* Also update the regs callback function */ if (!ret) { ip = (unsigned long)(&ftrace_regs_call); @@ -245,7 +242,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func) new = ftrace_call_replace(ip, (unsigned long)func); ret = ftrace_modify_code(ip, old, new); } -#endif atomic_dec(&modifying_ftrace_code);