From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751456AbdCQVcL (ORCPT ); Fri, 17 Mar 2017 17:32:11 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49588 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751180AbdCQVbe (ORCPT ); Fri, 17 Mar 2017 17:31:34 -0400 Message-Id: <20170317212350.877051775@infradead.org> User-Agent: quilt/0.63-1 Date: Fri, 17 Mar 2017 22:19:20 +0100 From: Peter Zijlstra To: mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com Cc: linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, arjan@linux.intel.com, bp@alien8.de, richard.weinberger@gmail.com, jpoimboe@redhat.com, peterz@infradead.org Subject: [PATCH 2/5] bug: Add _ONCE logic to report_bug() References: <20170317211918.393791494@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-warn-once.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Josh suggested moving the _ONCE logic inside the trap handler, using a bit in the bug_entry::flags field, avoiding the need for the extra variable. Sadly this only works for WARN_ON_ONCE(), since the others have printk() statements prior to triggering the trap. Still, this saves a fair amount of text and data: text data bss dec hex filename 10682460 4530992 843776 16057228 f5038c defconfig-build/vmlinux.1 10665111 4530096 843776 16038983 f4bc47 defconfig-build/vmlinux.2 Suggested-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) --- arch/arm64/include/asm/bug.h | 2 +- arch/parisc/include/asm/bug.h | 8 ++++---- arch/powerpc/include/asm/bug.h | 4 ++-- arch/s390/include/asm/bug.h | 4 ++-- arch/sh/include/asm/bug.h | 4 ++-- arch/x86/include/asm/bug.h | 2 +- include/asm-generic/bug.h | 18 +++++++++++++++++- include/asm-generic/vmlinux.lds.h | 3 +-- include/linux/bug.h | 2 +- lib/bug.c | 28 ++++++++++++++++++++-------- 10 files changed, 51 insertions(+), 24 deletions(-) --- a/arch/arm64/include/asm/bug.h +++ b/arch/arm64/include/asm/bug.h @@ -55,7 +55,7 @@ _BUGVERBOSE_LOCATION(__FILE__, __LINE__) unreachable(); \ } while (0) -#define __WARN_TAINT(taint) _BUG_FLAGS(BUGFLAG_TAINT(taint)) +#define __WARN_FLAGS(flags) _BUG_FLAGS(BUGFLAG_WARNING|(flags)) #endif /* ! CONFIG_GENERIC_BUG */ --- a/arch/parisc/include/asm/bug.h +++ b/arch/parisc/include/asm/bug.h @@ -46,7 +46,7 @@ #endif #ifdef CONFIG_DEBUG_BUGVERBOSE -#define __WARN_TAINT(taint) \ +#define __WARN_FLAGS(flags) \ do { \ asm volatile("\n" \ "1:\t" PARISC_BUG_BREAK_ASM "\n" \ @@ -56,11 +56,11 @@ "\t.org 2b+%c3\n" \ "\t.popsection" \ : : "i" (__FILE__), "i" (__LINE__), \ - "i" (BUGFLAG_TAINT(taint)), \ + "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry)) ); \ } while(0) #else -#define __WARN_TAINT(taint) \ +#define __WARN_FLAGS(flags) \ do { \ asm volatile("\n" \ "1:\t" PARISC_BUG_BREAK_ASM "\n" \ @@ -69,7 +69,7 @@ "\t.short %c0\n" \ "\t.org 2b+%c1\n" \ "\t.popsection" \ - : : "i" (BUGFLAG_TAINT(taint)), \ + : : "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry)) ); \ } while(0) #endif --- a/arch/powerpc/include/asm/bug.h +++ b/arch/powerpc/include/asm/bug.h @@ -85,12 +85,12 @@ } \ } while (0) -#define __WARN_TAINT(taint) do { \ +#define __WARN_FLAGS(flags) do { \ __asm__ __volatile__( \ "1: twi 31,0,0\n" \ _EMIT_BUG_ENTRY \ : : "i" (__FILE__), "i" (__LINE__), \ - "i" (BUGFLAG_TAINT(taint)), \ + "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry))); \ } while (0) --- a/arch/s390/include/asm/bug.h +++ b/arch/s390/include/asm/bug.h @@ -46,8 +46,8 @@ unreachable(); \ } while (0) -#define __WARN_TAINT(taint) do { \ - __EMIT_BUG(BUGFLAG_TAINT(taint)); \ +#define __WARN_FLAGS(flags) do { \ + __EMIT_BUG(BUGFLAG_WARNING|(flags)); \ } while (0) #define WARN_ON(x) ({ \ --- a/arch/sh/include/asm/bug.h +++ b/arch/sh/include/asm/bug.h @@ -50,7 +50,7 @@ do { \ "i" (sizeof(struct bug_entry))); \ } while (0) -#define __WARN_TAINT(taint) \ +#define __WARN_FLAGS(flags) \ do { \ __asm__ __volatile__ ( \ "1:\t.short %O0\n" \ @@ -59,7 +59,7 @@ do { \ : "n" (TRAPA_BUG_OPCODE), \ "i" (__FILE__), \ "i" (__LINE__), \ - "i" (BUGFLAG_TAINT(taint)), \ + "i" (BUGFLAG_WARNING|(flags)), \ "i" (sizeof(struct bug_entry))); \ } while (0) --- a/arch/x86/include/asm/bug.h +++ b/arch/x86/include/asm/bug.h @@ -64,7 +64,7 @@ do { \ unreachable(); \ } while (0) -#define __WARN_TAINT(taint) _BUG_FLAGS(ASM_UD0, BUGFLAG_TAINT(taint)) +#define __WARN_FLAGS(flags) _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags)) #include --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -5,6 +5,8 @@ #ifdef CONFIG_GENERIC_BUG #define BUGFLAG_WARNING (1 << 0) +#define BUGFLAG_ONCE (1 << 1) +#define BUGFLAG_DONE (1 << 2) #define BUGFLAG_TAINT(taint) (BUGFLAG_WARNING | ((taint) << 8)) #define BUG_GET_TAINT(bug) ((bug)->flags >> 8) #endif @@ -55,6 +57,18 @@ struct bug_entry { #define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0) #endif +#ifdef __WARN_FLAGS +#define __WARN_TAINT(taint) __WARN_FLAGS(BUGFLAG_TAINT(taint)) +#define __WARN_ONCE_TAINT(taint) __WARN_FLAGS(BUGFLAG_ONCE|BUGFLAG_TAINT(taint)) + +#define WARN_ON_ONCE(condition) ({ \ + int __ret_warn_on = !!(condition); \ + if (unlikely(__ret_warn_on)) \ + __WARN_ONCE_TAINT(TAINT_WARN); \ + unlikely(__ret_warn_on); \ +}) +#endif + /* * WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report * significant issues that need prompt attention if they should ever @@ -97,7 +111,7 @@ void __warn(const char *file, int line, #endif #ifndef WARN -#define WARN(condition, format...) ({ \ +#define WARN(condition, format...) ({ \ int __ret_warn_on = !!(condition); \ if (unlikely(__ret_warn_on)) \ __WARN_printf(format); \ @@ -112,6 +126,7 @@ void __warn(const char *file, int line, unlikely(__ret_warn_on); \ }) +#ifndef WARN_ON_ONCE #define WARN_ON_ONCE(condition) ({ \ static bool __section(.data.unlikely) __warned; \ int __ret_warn_once = !!(condition); \ @@ -122,6 +137,7 @@ void __warn(const char *file, int line, } \ unlikely(__ret_warn_once); \ }) +#endif #define WARN_ONCE(condition, format...) ({ \ static bool __section(.data.unlikely) __warned; \ --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -286,8 +286,6 @@ *(.rodata1) \ } \ \ - BUG_TABLE \ - \ /* PCI quirks */ \ .pci_fixup : AT(ADDR(.pci_fixup) - LOAD_OFFSET) { \ VMLINUX_SYMBOL(__start_pci_fixups_early) = .; \ @@ -855,6 +853,7 @@ READ_MOSTLY_DATA(cacheline) \ DATA_DATA \ CONSTRUCTORS \ + BUG_TABLE \ } #define INIT_TEXT_SECTION(inittext_align) \ --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -105,7 +105,7 @@ static inline int is_warning_bug(const s return bug->flags & BUGFLAG_WARNING; } -const struct bug_entry *find_bug(unsigned long bugaddr); +struct bug_entry *find_bug(unsigned long bugaddr); enum bug_trap_type report_bug(unsigned long bug_addr, struct pt_regs *regs); --- a/lib/bug.c +++ b/lib/bug.c @@ -47,7 +47,7 @@ #include #include -extern const struct bug_entry __start___bug_table[], __stop___bug_table[]; +extern struct bug_entry __start___bug_table[], __stop___bug_table[]; static inline unsigned long bug_addr(const struct bug_entry *bug) { @@ -62,10 +62,10 @@ static inline unsigned long bug_addr(con /* Updates are protected by module mutex */ static LIST_HEAD(module_bug_list); -static const struct bug_entry *module_find_bug(unsigned long bugaddr) +static struct bug_entry *module_find_bug(unsigned long bugaddr) { struct module *mod; - const struct bug_entry *bug = NULL; + struct bug_entry *bug = NULL; rcu_read_lock_sched(); list_for_each_entry_rcu(mod, &module_bug_list, bug_list) { @@ -122,15 +122,15 @@ void module_bug_cleanup(struct module *m #else -static inline const struct bug_entry *module_find_bug(unsigned long bugaddr) +static inline struct bug_entry *module_find_bug(unsigned long bugaddr) { return NULL; } #endif -const struct bug_entry *find_bug(unsigned long bugaddr) +struct bug_entry *find_bug(unsigned long bugaddr) { - const struct bug_entry *bug; + struct bug_entry *bug; for (bug = __start___bug_table; bug < __stop___bug_table; ++bug) if (bugaddr == bug_addr(bug)) @@ -141,9 +141,9 @@ const struct bug_entry *find_bug(unsigne enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) { - const struct bug_entry *bug; + struct bug_entry *bug; const char *file; - unsigned line, warning; + unsigned line, warning, once, done; if (!is_valid_bugaddr(bugaddr)) return BUG_TRAP_TYPE_NONE; @@ -164,6 +164,18 @@ enum bug_trap_type report_bug(unsigned l line = bug->line; #endif warning = (bug->flags & BUGFLAG_WARNING) != 0; + once = (bug->flags & BUGFLAG_ONCE) != 0; + done = (bug->flags & BUGFLAG_DONE) != 0; + + if (warning && once) { + if (done) + return BUG_TRAP_TYPE_WARN; + + /* + * Since this is the only store, concurrency is not an issue. + */ + bug->flags |= BUGFLAG_DONE; + } } if (warning) {