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Peter Anvin" , sparclinux@vger.kernel.org, Yoshinori Sato , linux-hexagon@vger.kernel.org, x86@kernel.org, Russell King , Ingo Molnar , James Hogan , linux-snps-arc@lists.infradead.org, Huang Ying , Greg Kroah-Hartman , Borislav Petkov , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Vineet Gupta , Douglas Anderson , Ralf Baechle , Richard Kuo , Paul Burton , Benjamin Herrenschmidt , Philippe Ombredanne , Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org The function kgdb_roundup_cpus() was passed a parameter that was documented as: > the flags that will be used when restoring the interrupts. There is > local_irq_save() call before kgdb_roundup_cpus(). Nobody used those flags. Anyone who wanted to temporarily turn on interrupts just did local_irq_enable() and local_irq_disable() without looking at them. So we can definitely remove the flags. Signed-off-by: Douglas Anderson --- Changes in v2: - Removing irq flags separated from fixing lockdep splat. arch/arc/kernel/kgdb.c | 2 +- arch/arm/kernel/kgdb.c | 2 +- arch/arm64/kernel/kgdb.c | 2 +- arch/hexagon/kernel/kgdb.c | 9 ++------- arch/mips/kernel/kgdb.c | 2 +- arch/powerpc/kernel/kgdb.c | 2 +- arch/sh/kernel/kgdb.c | 2 +- arch/sparc/kernel/smp_64.c | 2 +- arch/x86/kernel/kgdb.c | 9 ++------- include/linux/kgdb.h | 9 ++------- kernel/debug/debug_core.c | 2 +- 11 files changed, 14 insertions(+), 29 deletions(-) diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c index 9a3c34af2ae8..0932851028e0 100644 --- a/arch/arc/kernel/kgdb.c +++ b/arch/arc/kernel/kgdb.c @@ -197,7 +197,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), NULL); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index caa0dbe3dc61..f21077b077be 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -175,7 +175,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index a20de58061a8..12c339ff6e75 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -289,7 +289,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c index 16c24b22d0b2..012e0e230ac2 100644 --- a/arch/hexagon/kernel/kgdb.c +++ b/arch/hexagon/kernel/kgdb.c @@ -119,17 +119,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them be in a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ @@ -139,7 +134,7 @@ static void hexagon_kgdb_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0); diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index eb6c0d582626..2b05effc17b4 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -219,7 +219,7 @@ static void kgdb_call_nmi_hook(void *ignored) set_fs(old_fs); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index 59c578f865aa..b0e804844be0 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -124,7 +124,7 @@ static int kgdb_call_nmi_hook(struct pt_regs *regs) } #ifdef CONFIG_SMP -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { smp_send_debugger_break(); } diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c index 4f04c6638a4d..cc57630f6bf2 100644 --- a/arch/sh/kernel/kgdb.c +++ b/arch/sh/kernel/kgdb.c @@ -319,7 +319,7 @@ static void kgdb_call_nmi_hook(void *ignored) kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); } -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { local_irq_enable(); smp_call_function(kgdb_call_nmi_hook, NULL, 0); diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c index d3ea1f3c06a0..68098bbf3705 100644 --- a/arch/sparc/kernel/smp_64.c +++ b/arch/sparc/kernel/smp_64.c @@ -1014,7 +1014,7 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page) } #ifdef CONFIG_KGDB -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { smp_cross_call(&xcall_kgdb_capture, 0, 0, 0); } diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c index 8e36f249646e..ac6291a4178d 100644 --- a/arch/x86/kernel/kgdb.c +++ b/arch/x86/kernel/kgdb.c @@ -422,21 +422,16 @@ static void kgdb_disable_hw_debug(struct pt_regs *regs) #ifdef CONFIG_SMP /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them be in a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ -void kgdb_roundup_cpus(unsigned long flags) +void kgdb_roundup_cpus(void) { apic->send_IPI_allbutself(APIC_DM_NMI); } diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index e465bb15912d..05e5b2eb0d32 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -178,21 +178,16 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code, /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * @flags: Current IRQ state * * On SMP systems, we need to get the attention of the other CPUs * and get them into a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. In - * this case, we have to make sure that interrupts are enabled before - * calling smp_call_function(). The argument to this function is - * the flags that will be used when restoring the interrupts. There is - * local_irq_save() call before kgdb_roundup_cpus(). + * in case of MIPS, smp_call_function() is used to roundup CPUs. * * On non-SMP systems, this is not called. */ -extern void kgdb_roundup_cpus(unsigned long flags); +extern void kgdb_roundup_cpus(void); /** * kgdb_arch_set_pc - Generic call back to the program counter diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 65c0f1363788..f3cadda45f07 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -593,7 +593,7 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, /* Signal the other CPUs to enter kgdb_wait() */ else if ((!kgdb_single_step) && kgdb_do_roundup) - kgdb_roundup_cpus(flags); + kgdb_roundup_cpus(); #endif /* From patchwork Tue Oct 30 22:18:43 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Doug Anderson X-Patchwork-Id: 991151 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; 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Tue, 30 Oct 2018 15:19:07 -0700 (PDT) Received: from tictac2.mtv.corp.google.com ([2620:15c:202:1:c8e0:70d7:4be7:a36]) by smtp.gmail.com with ESMTPSA id c70-v6sm2889774pfe.93.2018.10.30.15.19.05 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 30 Oct 2018 15:19:06 -0700 (PDT) From: Douglas Anderson To: Jason Wessel , Daniel Thompson Subject: [PATCH v2 2/2] kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function() Date: Tue, 30 Oct 2018 15:18:43 -0700 Message-Id: <20181030221843.121254-3-dianders@chromium.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181030221843.121254-1-dianders@chromium.org> References: <20181030221843.121254-1-dianders@chromium.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181030_151918_179584_C639D825 X-CRM114-Status: GOOD ( 23.90 ) X-Spam-Score: -0.6 (/) X-Spam-Report: SpamAssassin version 3.4.1 on bombadil.infradead.org summary: Content analysis details: (-0.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:444 listed in] [list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.5 DKIMWL_WL_HIGH DKIMwl.org - Whitelisted High sender X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kate Stewart , linux-mips@linux-mips.org, Rich Felker , Benjamin Herrenschmidt , linux-sh@vger.kernel.org, Peter Zijlstra , Catalin Marinas , Will Deacon , linux-kernel@vger.kernel.org, Paul Mackerras , Michael Ellerman , Yoshinori Sato , linux-hexagon@vger.kernel.org, Russell King , kgdb-bugreport@lists.sourceforge.net, James Hogan , linux-snps-arc@lists.infradead.org, Greg Kroah-Hartman , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Christophe Leroy , Vineet Gupta , Douglas Anderson , Ralf Baechle , Richard Kuo , Paul Burton , Philippe Ombredanne , linuxppc-dev@lists.ozlabs.org Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org When I had lockdep turned on and dropped into kgdb I got a nice splat on my system. Specifically it hit: DEBUG_LOCKS_WARN_ON(current->hardirq_context) Specifically it looked like this: sysrq: SysRq : DEBUG ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(current->hardirq_context) WARNING: CPU: 0 PID: 0 at .../kernel/locking/lockdep.c:2875 lockdep_hardirqs_on+0xf0/0x160 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0 #27 pstate: 604003c9 (nZCv DAIF +PAN -UAO) pc : lockdep_hardirqs_on+0xf0/0x160 ... Call trace: lockdep_hardirqs_on+0xf0/0x160 trace_hardirqs_on+0x188/0x1ac kgdb_roundup_cpus+0x14/0x3c kgdb_cpu_enter+0x53c/0x5cc kgdb_handle_exception+0x180/0x1d4 kgdb_compiled_brk_fn+0x30/0x3c brk_handler+0x134/0x178 do_debug_exception+0xfc/0x178 el1_dbg+0x18/0x78 kgdb_breakpoint+0x34/0x58 sysrq_handle_dbg+0x54/0x5c __handle_sysrq+0x114/0x21c handle_sysrq+0x30/0x3c qcom_geni_serial_isr+0x2dc/0x30c ... ... irq event stamp: ...45 hardirqs last enabled at (...44): [...] __do_softirq+0xd8/0x4e4 hardirqs last disabled at (...45): [...] el1_irq+0x74/0x130 softirqs last enabled at (...42): [...] _local_bh_enable+0x2c/0x34 softirqs last disabled at (...43): [...] irq_exit+0xa8/0x100 ---[ end trace adf21f830c46e638 ]--- Looking closely at it, it seems like a really bad idea to be calling local_irq_enable() in kgdb_roundup_cpus(). If nothing else that seems like it could violate spinlock semantics and cause a deadlock. Instead, let's use a private csd alongside smp_call_function_single_async() to round up the other CPUs. Using smp_call_function_single_async() doesn't require interrupts to be enabled so we can remove the offending bit of code. In order to avoid duplicating this across all the architectures that use the default kgdb_roundup_cpus(), we'll add a "weak" implementation to debug_core.c. Looking at all the people who previously had copies of this code, there were a few variants. I've attempted to keep the variants working like they used to. Specifically: * For arch/arc we passed NULL to kgdb_nmicallback() instead of get_irq_regs(). * For arch/mips there was a bit of extra code around kgdb_nmicallback() Suggested-by: Daniel Thompson Signed-off-by: Douglas Anderson --- Changes in v2: - Removing irq flags separated from fixing lockdep splat. - Don't use smp_call_function (Daniel). arch/arc/kernel/kgdb.c | 10 ++-------- arch/arm/kernel/kgdb.c | 12 ------------ arch/arm64/kernel/kgdb.c | 12 ------------ arch/hexagon/kernel/kgdb.c | 27 --------------------------- arch/mips/kernel/kgdb.c | 9 +-------- arch/powerpc/kernel/kgdb.c | 4 ++-- arch/sh/kernel/kgdb.c | 12 ------------ include/linux/kgdb.h | 15 +++++++++++++-- kernel/debug/debug_core.c | 36 ++++++++++++++++++++++++++++++++++++ 9 files changed, 54 insertions(+), 83 deletions(-) diff --git a/arch/arc/kernel/kgdb.c b/arch/arc/kernel/kgdb.c index 0932851028e0..68d9fe4b5aa7 100644 --- a/arch/arc/kernel/kgdb.c +++ b/arch/arc/kernel/kgdb.c @@ -192,18 +192,12 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip) instruction_pointer(regs) = ip; } -static void kgdb_call_nmi_hook(void *ignored) +void kgdb_call_nmi_hook(void *ignored) { + /* Default implementation passes get_irq_regs() but we don't */ kgdb_nmicallback(raw_smp_processor_id(), NULL); } -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - struct kgdb_arch arch_kgdb_ops = { /* breakpoint instruction: TRAP_S 0x3 */ #ifdef CONFIG_CPU_BIG_ENDIAN diff --git a/arch/arm/kernel/kgdb.c b/arch/arm/kernel/kgdb.c index f21077b077be..d9a69e941463 100644 --- a/arch/arm/kernel/kgdb.c +++ b/arch/arm/kernel/kgdb.c @@ -170,18 +170,6 @@ static struct undef_hook kgdb_compiled_brkpt_hook = { .fn = kgdb_compiled_brk_fn }; -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index 12c339ff6e75..da880247c734 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -284,18 +284,6 @@ static struct step_hook kgdb_step_hook = { .fn = kgdb_step_brk_fn }; -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { struct pt_regs *regs = args->regs; diff --git a/arch/hexagon/kernel/kgdb.c b/arch/hexagon/kernel/kgdb.c index 012e0e230ac2..b95d12038a4e 100644 --- a/arch/hexagon/kernel/kgdb.c +++ b/arch/hexagon/kernel/kgdb.c @@ -115,33 +115,6 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) instruction_pointer(regs) = pc; } -#ifdef CONFIG_SMP - -/** - * kgdb_roundup_cpus - Get other CPUs into a holding pattern - * - * On SMP systems, we need to get the attention of the other CPUs - * and get them be in a known state. This should do what is needed - * to get the other CPUs to call kgdb_wait(). Note that on some arches, - * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. - * - * On non-SMP systems, this is not called. - */ - -static void hexagon_kgdb_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(hexagon_kgdb_nmi_hook, NULL, 0); - local_irq_disable(); -} -#endif - /* Not yet working */ void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, diff --git a/arch/mips/kernel/kgdb.c b/arch/mips/kernel/kgdb.c index 2b05effc17b4..42f057a6c215 100644 --- a/arch/mips/kernel/kgdb.c +++ b/arch/mips/kernel/kgdb.c @@ -207,7 +207,7 @@ void arch_kgdb_breakpoint(void) ".set\treorder"); } -static void kgdb_call_nmi_hook(void *ignored) +void kgdb_call_nmi_hook(void *ignored) { mm_segment_t old_fs; @@ -219,13 +219,6 @@ static void kgdb_call_nmi_hook(void *ignored) set_fs(old_fs); } -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int compute_signal(int tt) { struct hard_trap_info *ht; diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index b0e804844be0..b4ce54d73337 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -117,7 +117,7 @@ int kgdb_skipexception(int exception, struct pt_regs *regs) return kgdb_isremovedbreak(regs->nip); } -static int kgdb_call_nmi_hook(struct pt_regs *regs) +static int kgdb_debugger_ipi(struct pt_regs *regs) { kgdb_nmicallback(raw_smp_processor_id(), regs); return 0; @@ -502,7 +502,7 @@ int kgdb_arch_init(void) old__debugger_break_match = __debugger_break_match; old__debugger_fault_handler = __debugger_fault_handler; - __debugger_ipi = kgdb_call_nmi_hook; + __debugger_ipi = kgdb_debugger_ipi; __debugger = kgdb_debugger; __debugger_bpt = kgdb_handle_breakpoint; __debugger_sstep = kgdb_singlestep; diff --git a/arch/sh/kernel/kgdb.c b/arch/sh/kernel/kgdb.c index cc57630f6bf2..14e012ad7c57 100644 --- a/arch/sh/kernel/kgdb.c +++ b/arch/sh/kernel/kgdb.c @@ -314,18 +314,6 @@ BUILD_TRAP_HANDLER(singlestep) local_irq_restore(flags); } -static void kgdb_call_nmi_hook(void *ignored) -{ - kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); -} - -void kgdb_roundup_cpus(void) -{ - local_irq_enable(); - smp_call_function(kgdb_call_nmi_hook, NULL, 0); - local_irq_disable(); -} - static int __kgdb_notify(struct die_args *args, unsigned long cmd) { int ret; diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index 05e5b2eb0d32..f4f866273ed2 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -176,14 +176,25 @@ kgdb_arch_handle_exception(int vector, int signo, int err_code, char *remcom_out_buffer, struct pt_regs *regs); +/** + * kgdb_call_nmi_hook - Call kgdb_nmicallback() on the current CPU + * + * If you're using the default implementation of kgdb_roundup_cpus() + * this function will be called per CPU. If you don't implement + * kgdb_call_nmi_hook() a default will be used. + */ + +extern void kgdb_call_nmi_hook(void *ignored); + + /** * kgdb_roundup_cpus - Get other CPUs into a holding pattern * * On SMP systems, we need to get the attention of the other CPUs * and get them into a known state. This should do what is needed * to get the other CPUs to call kgdb_wait(). Note that on some arches, - * the NMI approach is not used for rounding up all the CPUs. For example, - * in case of MIPS, smp_call_function() is used to roundup CPUs. + * the NMI approach is not used for rounding up all the CPUs. Normally + * those architectures can just not implement this and get the default. * * On non-SMP systems, this is not called. */ diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index f3cadda45f07..9a3f952de6ed 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -55,6 +55,7 @@ #include #include #include +#include #include #include @@ -220,6 +221,39 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs) return 0; } +/* + * Default (weak) implementation for kgdb_roundup_cpus + */ + +static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd); + +void __weak kgdb_call_nmi_hook(void *ignored) +{ + kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); +} + +void __weak kgdb_roundup_cpus(void) +{ + call_single_data_t *csd; + int cpu; + + for_each_cpu(cpu, cpu_online_mask) { + csd = &per_cpu(kgdb_roundup_csd, cpu); + smp_call_function_single_async(cpu, csd); + } +} + +static void kgdb_generic_roundup_init(void) +{ + call_single_data_t *csd; + int cpu; + + for_each_possible_cpu(cpu) { + csd = &per_cpu(kgdb_roundup_csd, cpu); + csd->func = kgdb_call_nmi_hook; + } +} + /* * Some architectures need cache flushes when we set/clear a * breakpoint: @@ -993,6 +1027,8 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) return -EBUSY; } + kgdb_generic_roundup_init(); + if (new_dbg_io_ops->init) { err = new_dbg_io_ops->init(); if (err) {