From: kbuild test robot <lkp@intel.com>
To: kbuild@lists.01.org
Subject: [tglx-devel:x86/entry 100/140] arch/x86/kernel/traps.c:721:16: warning: Using argument dr6 that points at uninitialized variable dr6 [ctuuninitvar]
Date: Wed, 06 May 2020 05:39:39 +0800 [thread overview]
Message-ID: <202005060530.w5ecQnM3%lkp@intel.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 4628 bytes --]
CC: kbuild-all(a)lists.01.org
TO: Peter Zijlstra <peterz@infradead.org>
CC: Thomas Gleixner <tglx@linutronix.de>
tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/entry
head: e6d36eed49b863bbe393e3c07cae737cd9c475e3
commit: e41ec789a83eaaa28efb7b897a48cb565e9aa067 [100/140] x86/db: Split out dr6/7 handling
:::::: branch date: 12 hours ago
:::::: commit date: 12 hours ago
If you fix the issue, kindly add following tag as appropriate
Reported-by: kbuild test robot <lkp@intel.com>
cppcheck warnings: (new ones prefixed by >>)
>> arch/x86/kernel/traps.c:721:16: warning: Using argument dr6 that points at uninitialized variable dr6 [ctuuninitvar]
get_debugreg(*dr6, 6);
^
arch/x86/kernel/traps.c:763:13: note: Calling function debug_enter, 1st argument is uninitialized
debug_enter(&dr6, &dr7);
^
arch/x86/kernel/traps.c:721:16: note: Using argument dr6
get_debugreg(*dr6, 6);
^
>> arch/x86/kernel/traps.c:707:16: warning: Using argument dr7 that points at uninitialized variable dr7 [ctuuninitvar]
get_debugreg(*dr7, 6);
^
arch/x86/kernel/traps.c:763:13: note: Calling function debug_enter, 2nd argument is uninitialized
debug_enter(&dr6, &dr7);
^
arch/x86/kernel/traps.c:707:16: note: Using argument dr7
get_debugreg(*dr7, 6);
^
# https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git/commit/?id=e41ec789a83eaaa28efb7b897a48cb565e9aa067
git remote add tglx-devel https://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git
git remote update tglx-devel
git checkout e41ec789a83eaaa28efb7b897a48cb565e9aa067
vim +721 arch/x86/kernel/traps.c
f2b375756c839ff Andy Lutomirski 2016-03-09 693
e41ec789a83eaaa Peter Zijlstra 2020-04-06 694 static __always_inline void debug_enter(unsigned long *dr6, unsigned long *dr7)
e41ec789a83eaaa Peter Zijlstra 2020-04-06 695 {
e41ec789a83eaaa Peter Zijlstra 2020-04-06 696 /*
e41ec789a83eaaa Peter Zijlstra 2020-04-06 697 * Disable breakpoints during exception handling; recursive exceptions
e41ec789a83eaaa Peter Zijlstra 2020-04-06 698 * are exceedingly 'fun'.
e41ec789a83eaaa Peter Zijlstra 2020-04-06 699 *
e41ec789a83eaaa Peter Zijlstra 2020-04-06 700 * Since this function is NOKPROBE, and that also applies to
e41ec789a83eaaa Peter Zijlstra 2020-04-06 701 * HW_BREAKPOINT_X, we can't hit a breakpoint before this (XXX except a
e41ec789a83eaaa Peter Zijlstra 2020-04-06 702 * HW_BREAKPOINT_W on our stack)
e41ec789a83eaaa Peter Zijlstra 2020-04-06 703 *
e41ec789a83eaaa Peter Zijlstra 2020-04-06 704 * Entry text is excluded for HW_BP_X and cpu_entry_area, which
e41ec789a83eaaa Peter Zijlstra 2020-04-06 705 * includes the entry stack is excluded for everything.
e41ec789a83eaaa Peter Zijlstra 2020-04-06 706 */
e41ec789a83eaaa Peter Zijlstra 2020-04-06 @707 get_debugreg(*dr7, 6);
e41ec789a83eaaa Peter Zijlstra 2020-04-06 708 set_debugreg(0, 7);
e41ec789a83eaaa Peter Zijlstra 2020-04-06 709
e41ec789a83eaaa Peter Zijlstra 2020-04-06 710 /*
e41ec789a83eaaa Peter Zijlstra 2020-04-06 711 * The Intel SDM says:
e41ec789a83eaaa Peter Zijlstra 2020-04-06 712 *
e41ec789a83eaaa Peter Zijlstra 2020-04-06 713 * Certain debug exceptions may clear bits 0-3. The remaining
e41ec789a83eaaa Peter Zijlstra 2020-04-06 714 * contents of the DR6 register are never cleared by the
e41ec789a83eaaa Peter Zijlstra 2020-04-06 715 * processor. To avoid confusion in identifying debug
e41ec789a83eaaa Peter Zijlstra 2020-04-06 716 * exceptions, debug handlers should clear the register before
e41ec789a83eaaa Peter Zijlstra 2020-04-06 717 * returning to the interrupted task.
e41ec789a83eaaa Peter Zijlstra 2020-04-06 718 *
e41ec789a83eaaa Peter Zijlstra 2020-04-06 719 * Keep it simple: clear DR6 immediately.
e41ec789a83eaaa Peter Zijlstra 2020-04-06 720 */
e41ec789a83eaaa Peter Zijlstra 2020-04-06 @721 get_debugreg(*dr6, 6);
e41ec789a83eaaa Peter Zijlstra 2020-04-06 722 set_debugreg(0, 6);
e41ec789a83eaaa Peter Zijlstra 2020-04-06 723 /* Filter out all the reserved bits which are preset to 1 */
e41ec789a83eaaa Peter Zijlstra 2020-04-06 724 *dr6 &= ~DR6_RESERVED;
e41ec789a83eaaa Peter Zijlstra 2020-04-06 725 }
e41ec789a83eaaa Peter Zijlstra 2020-04-06 726
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org
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