Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756361AbZKIPdi (ORCPT ); Mon, 9 Nov 2009 10:33:38 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756344AbZKIPdg (ORCPT ); Mon, 9 Nov 2009 10:33:36 -0500 Received: from mail-ew0-f207.google.com ([209.85.219.207]:39623 "EHLO mail-ew0-f207.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756339AbZKIPde (ORCPT ); Mon, 9 Nov 2009 10:33:34 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references; b=SutUslWo4CEKX7eDnGmdGucECSW5mZ4QtppP1Ck8h93VaGX8Ggcmor6jyL4Ad1UUcN vPt3WzbgMqavaR4NZJqAZ490PPX+1Zvb7nXjOUv6nTZZlv9ysDxxuE/cUMhJOY/SQYfW ELf1WPUYjwsDjuovutR9n4V2HWRauvaPQ69e4= From: Wu Zhangjin To: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org Cc: zhangfx@lemote.com, zhouqg@gmail.com, Wu Zhangjin , Ralf Baechle , rostedt@goodmis.org, Frederic Weisbecker , Ingo Molnar , Nicholas Mc Guire , David Daney , Richard Sandiford , Patrik Kluba , Thomas Gleixner , Michal Simek Subject: [PATCH v7 15/17] tracing: make ftrace for MIPS more robust Date: Mon, 9 Nov 2009 23:31:32 +0800 Message-Id: <406a8e5e3117737e401bb2bba84ad9b17f99857d.1257779502.git.wuzhangjin@gmail.com> X-Mailer: git-send-email 1.6.2.1 In-Reply-To: <695747bff7cddb97d6f43c05c4cf05eb269e402d.1257779502.git.wuzhangjin@gmail.com> References: <9dc81a7a9e5a292cccdf465c533a2b08d19d6021.1257779502.git.wuzhangjin@gmail.com> <8f579e2cece16cd22358a4ec143ef6a8c462639b.1257779502.git.wuzhangjin@gmail.com> <6199d7b3956b544fc65896af1062787a2e1283ce.1257779502.git.wuzhangjin@gmail.com> <58a7558730fbea6cd0417100c8fcd6f45668d1e3.1257779502.git.wuzhangjin@gmail.com> <3a9fc9ca02e8e6e9c3c28797a4c084c1f9d91f69.1257779502.git.wuzhangjin@gmail.com> <0cef783a71333ff96a78aaea8961e3b6b5392665.1257779502.git.wuzhangjin@gmail.com> <18e1d617ed824bb1c10f15216f2ed9ed3de78abd.1257779502.git.wuzhangjin@gmail.com> <3da916c1cb6e05445438826f98a91111f43ff6cd.1257779502.git.wuzhangjin@gmail.com> <451c55dead5d6afd871de6afd14dbbcf70a0f834.1257779502.git.wuzhangjin@gmail.com> <0c463e2af521e613fd15751a9f610c74cf887292.1257779502.git.wuzhangjin@gmail.com> <695747bff7cddb97d6f43c05c4cf05eb269e402d.1257779502.git.wuzhangjin@gmail.com> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5703 Lines: 204 From: Wu Zhangjin Seems there is no failure meet when working with the C source code to load/hijack the text & stack space, but we must ensure our source code is robust enough, This patch does it via adding extra exception handling. Signed-off-by: Wu Zhangjin --- arch/mips/include/asm/ftrace.h | 57 ++++++++++++++++++++++++++++++++++++++++ arch/mips/kernel/ftrace.c | 46 +++++++++++++++++++++++--------- 2 files changed, 90 insertions(+), 13 deletions(-) diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrace.h index aa7c80b..f78d763 100644 --- a/arch/mips/include/asm/ftrace.h +++ b/arch/mips/include/asm/ftrace.h @@ -19,6 +19,62 @@ extern void _mcount(void); #define mcount _mcount +#define safe_load(load, src, dst, error) \ +do { \ + asm volatile ( \ + "1: " load " %[" STR(dst) "], 0(%[" STR(src) "])\n"\ + " li %[" STR(error) "], 0\n" \ + "2:\n" \ + \ + ".section .fixup, \"ax\"\n" \ + "3: li %[" STR(error) "], 1\n" \ + " j 2b\n" \ + ".previous\n" \ + \ + ".section\t__ex_table,\"a\"\n\t" \ + STR(PTR) "\t1b, 3b\n\t" \ + ".previous\n" \ + \ + : [dst] "=&r" (dst), [error] "=r" (error)\ + : [src] "r" (src) \ + : "memory" \ + ); \ +} while (0) + +#define safe_store(store, src, dst, error) \ +do { \ + asm volatile ( \ + "1: " store " %[" STR(src) "], 0(%[" STR(dst) "])\n"\ + " li %[" STR(error) "], 0\n" \ + "2:\n" \ + \ + ".section .fixup, \"ax\"\n" \ + "3: li %[" STR(error) "], 1\n" \ + " j 2b\n" \ + ".previous\n" \ + \ + ".section\t__ex_table,\"a\"\n\t"\ + STR(PTR) "\t1b, 3b\n\t" \ + ".previous\n" \ + \ + : [error] "=r" (error) \ + : [dst] "r" (dst), [src] "r" (src)\ + : "memory" \ + ); \ +} while (0) + +#define safe_load_code(dst, src, error) \ + safe_load(STR(lw), src, dst, error) +#define safe_store_code(src, dst, error) \ + safe_store(STR(sw), src, dst, error) + +#define safe_load_stack(dst, src, error) \ + safe_load(STR(PTR_L), src, dst, error) + +#define safe_store_stack(src, dst, error) \ + safe_store(STR(PTR_S), src, dst, error) + + #ifdef CONFIG_DYNAMIC_FTRACE static inline unsigned long ftrace_call_adjust(unsigned long addr) { @@ -27,6 +83,7 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) struct dyn_arch_ftrace { }; + #endif /* CONFIG_DYNAMIC_FTRACE */ /* not trace the timecounter_read* in kernel/time/clocksource.c */ diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c index af3ceed..a4e25b8 100644 --- a/arch/mips/kernel/ftrace.c +++ b/arch/mips/kernel/ftrace.c @@ -31,7 +31,13 @@ static unsigned int ftrace_nop = 0x00000000; static int ftrace_modify_code(unsigned long ip, unsigned int new_code) { - *(unsigned int *)ip = new_code; + int faulted; + + /* *(unsigned int *)ip = new_code; */ + safe_store_code(new_code, ip, faulted); + + if (unlikely(faulted)) + return -EFAULT; flush_icache_range(ip, ip + 8); @@ -124,6 +130,7 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, { unsigned long sp, ip, ra; unsigned int code; + int faulted; /* move to the instruction "lui v1, HI_16BIT_OF_MCOUNT" */ ip = self_addr - 20; @@ -133,8 +140,11 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, do { ip -= 4; - /* get the code at "ip" */ - code = *(unsigned int *)ip; + /* get the code at "ip": code = *(unsigned int *)ip; */ + safe_load_code(code, ip, faulted); + + if (unlikely(faulted)) + return 0; /* If we hit the non-store instruction before finding where the * ra is stored, then this is a leaf function and it does not @@ -145,11 +155,14 @@ unsigned long ftrace_get_parent_addr(unsigned long self_addr, } while (((code & S_RA_SP) != S_RA_SP)); sp = fp + (code & OFFSET_MASK); - ra = *(unsigned long *)sp; + + /* ra = *(unsigned long *)sp; */ + safe_load_stack(ra, sp, faulted); + if (unlikely(faulted)) + return 0; if (ra == parent) return sp; - return 0; } @@ -164,6 +177,7 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, struct ftrace_graph_ent trace; unsigned long return_hooker = (unsigned long) &return_to_handler; + int faulted; if (unlikely(atomic_read(¤t->tracing_graph_pause))) return; @@ -177,21 +191,23 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, * ftrace_get_parent_addr() does it! */ - old = *parent; + /* old = *parent; */ + safe_load_stack(old, parent, faulted); + if (unlikely(faulted)) + goto out; parent = (unsigned long *)ftrace_get_parent_addr(self_addr, old, (unsigned long)parent, fp); - /* If fails when getting the stack address of the non-leaf function's * ra, stop function graph tracer and return */ - if (parent == 0) { - ftrace_graph_stop(); - WARN_ON(1); - return; - } + if (parent == 0) + goto out; - *parent = return_hooker; + /* *parent = return_hooker; */ + safe_store_stack(return_hooker, parent, faulted); + if (unlikely(faulted)) + goto out; if (ftrace_push_return_trace(old, self_addr, &trace.depth, fp) == -EBUSY) { @@ -206,5 +222,9 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, current->curr_ret_stack--; *parent = old; } + return; +out: + ftrace_graph_stop(); + WARN_ON(1); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -- 1.6.2.1 -- 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/