Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755444AbcKVJUg (ORCPT ); Tue, 22 Nov 2016 04:20:36 -0500 Received: from mail-pg0-f67.google.com ([74.125.83.67]:34689 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752774AbcKVJUe (ORCPT ); Tue, 22 Nov 2016 04:20:34 -0500 From: Boqun Feng To: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Boqun Feng , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , Andrew Donnellan , Christophe Leroy , "Aneesh Kumar K.V" , Rashmica Gupta , Douglas Miller Subject: [RFC v2] powerpc: xmon: Add address lookup for percpu symbols Date: Tue, 22 Nov 2016 17:20:09 +0800 Message-Id: <20161122092033.7869-1-boqun.feng@gmail.com> X-Mailer: git-send-email 2.10.1 In-Reply-To: <20161117094051.21606-1-boqun.feng@gmail.com> References: <20161117094051.21606-1-boqun.feng@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2520 Lines: 92 Currently, in xmon, there is no obvious way to get an address for a percpu symbol for a particular cpu. Having such an ability would be good for debugging the system when percpu variables got involved. Therefore, this patch introduces a new xmon command "lp" to lookup the address for percpu symbols. Usage of "lp" is similar to "ls", except that we could add a cpu number to choose the variable of which cpu we want to lookup. If no cpu number is given, lookup for current cpu. Signed-off-by: Boqun Feng --- v1 --> v2: o Using per_cpu_ptr() and this_cpu_ptr() instead of per_cpu_offset() and my_cpu_offset, because the latter are undefined on !SMP kernel. o Only print the address of percpu symbols, i.e. symbols in [__per_cpu_start, __per_cpu_end) arch/powerpc/xmon/xmon.c | 35 ++++++++++++++++++++++++++++++++++- 1 file changed, 34 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c index 760545519a0b..2747c94400a2 100644 --- a/arch/powerpc/xmon/xmon.c +++ b/arch/powerpc/xmon/xmon.c @@ -49,6 +49,7 @@ #include #include +#include #ifdef CONFIG_PPC64 #include @@ -229,6 +230,7 @@ Commands:\n\ f flush cache\n\ la lookup symbol+offset of specified address\n\ ls lookup address of specified symbol\n\ + lp s [#] lookup address of percpu symbol s for current cpu, or cpu #\n\ m examine/change memory\n\ mm move a block of memory\n\ ms set a block of memory\n\ @@ -2943,7 +2945,8 @@ static void symbol_lookup(void) { int type = inchar(); - unsigned long addr; + unsigned long addr, cpu; + void __percpu *ptr = NULL; static char tmp[64]; switch (type) { @@ -2967,6 +2970,36 @@ symbol_lookup(void) catch_memory_errors = 0; termch = 0; break; + case 'p': + getstring(tmp, 64); + if (setjmp(bus_error_jmp) == 0) { + catch_memory_errors = 1; + sync(); + ptr = (void __percpu *)kallsyms_lookup_name(tmp); + sync(); + } + + if (ptr && ptr >= (void __percpu *)__per_cpu_start + && ptr < (void __percpu *)__per_cpu_end) { + + if (scanhex(&cpu) && cpu < num_possible_cpus()) + addr = (unsigned long)per_cpu_ptr(ptr, cpu); + else { + cpu = raw_smp_processor_id(); + addr = (unsigned long)this_cpu_ptr(ptr); + } + + printf("%s for cpu 0x%lx: %lx\n", tmp, cpu, addr); + + } else { + printf("Percpu symbol '%s' not found.\n", tmp); + } + + + + catch_memory_errors = 0; + termch = 0; + break; } } -- 2.10.1