Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964997AbbHKMzj (ORCPT ); Tue, 11 Aug 2015 08:55:39 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:49787 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934191AbbHKMzf (ORCPT ); Tue, 11 Aug 2015 08:55:35 -0400 From: Luis Henriques To: Alexey Brodkin Cc: arc-linux-dev@synopsys.com, linux-kernel@vger.kernel.org, Vineet Gupta , Luis Henriques , kernel-team@lists.ubuntu.com Subject: [3.16.y-ckt stable] Patch "ARC: make sure instruction_pointer() returns unsigned value" has been added to staging queue Date: Tue, 11 Aug 2015 13:55:29 +0100 Message-Id: <1439297729-29631-1-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3978 Lines: 99 This is a note to let you know that I have just added a patch titled ARC: make sure instruction_pointer() returns unsigned value to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.16.y-queue This patch is scheduled to be released in version 3.16.7-ckt16. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.16.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ >From c7bc79956a634da40b323e3cf71650a3c08cecd3 Mon Sep 17 00:00:00 2001 From: Alexey Brodkin Date: Mon, 13 Jul 2015 10:25:17 +0300 Subject: ARC: make sure instruction_pointer() returns unsigned value commit f51e2f1911122879eefefa4c592dea8bf794b39c upstream. Currently instruction_pointer() returns pt_regs->ret and so return value is of type "long", which implicitly stands for "signed long". While that's perfectly fine when dealing with 32-bit values if return value of instruction_pointer() gets assigned to 64-bit variable sign extension may happen. And at least in one real use-case it happens already. In perf_prepare_sample() return value of perf_instruction_pointer() (which is an alias to instruction_pointer() in case of ARC) is assigned to (struct perf_sample_data)->ip (which type is "u64"). And what we see if instuction pointer points to user-space application that in case of ARC lays below 0x8000_0000 "ip" gets set properly with leading 32 zeros. But if instruction pointer points to kernel address space that starts from 0x8000_0000 then "ip" is set with 32 leadig "f"-s. I.e. id instruction_pointer() returns 0x8100_0000, "ip" will be assigned with 0xffff_ffff__8100_0000. Which is obviously wrong. In particular that issuse broke output of perf, because perf was unable to associate addresses like 0xffff_ffff__8100_0000 with anything from /proc/kallsyms. That's what we used to see: ----------->8---------- 6.27% ls [unknown] [k] 0xffffffff8046c5cc 2.96% ls libuClibc-0.9.34-git.so [.] memcpy 2.25% ls libuClibc-0.9.34-git.so [.] memset 1.66% ls [unknown] [k] 0xffffffff80666536 1.54% ls libuClibc-0.9.34-git.so [.] 0x000224d6 1.18% ls libuClibc-0.9.34-git.so [.] 0x00022472 ----------->8---------- With that change perf output looks much better now: ----------->8---------- 8.21% ls [kernel.kallsyms] [k] memset 3.52% ls libuClibc-0.9.34-git.so [.] memcpy 2.11% ls libuClibc-0.9.34-git.so [.] malloc 1.88% ls libuClibc-0.9.34-git.so [.] memset 1.64% ls [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore 1.41% ls [kernel.kallsyms] [k] __d_lookup_rcu ----------->8---------- Signed-off-by: Alexey Brodkin Cc: arc-linux-dev@synopsys.com Cc: linux-kernel@vger.kernel.org Signed-off-by: Vineet Gupta Signed-off-by: Luis Henriques --- arch/arc/include/asm/ptrace.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h index 1bfeec2c0558..2a58af7a2e3a 100644 --- a/arch/arc/include/asm/ptrace.h +++ b/arch/arc/include/asm/ptrace.h @@ -63,7 +63,7 @@ struct callee_regs { long r25, r24, r23, r22, r21, r20, r19, r18, r17, r16, r15, r14, r13; }; -#define instruction_pointer(regs) ((regs)->ret) +#define instruction_pointer(regs) (unsigned long)((regs)->ret) #define profile_pc(regs) instruction_pointer(regs) /* return 1 if user mode or 0 if kernel mode */ -- 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/