user/sven/linux.git/include/linux/kgdb.h, branch v5.3.11

kgdb/treewide: constify struct kgdb_arch arch_kgdb_ops

2018-12-30T08:33:06Z

checkpatch.pl reports the following: WARNING: struct kgdb_arch should normally be const #28: FILE: arch/mips/kernel/kgdb.c:397: +struct kgdb_arch arch_kgdb_ops = { This report makes sense, as all other ops struct, this one should also be const. This patch does the change. Cc: Vineet Gupta Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Yoshinori Sato Cc: Richard Kuo Cc: Michal Simek Cc: Ralf Baechle Cc: Paul Burton Cc: James Hogan Cc: Ley Foon Tan Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Rich Felker Cc: "David S. Miller" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: x86@kernel.org Acked-by: Daniel Thompson Acked-by: Paul Burton Signed-off-by: Christophe Leroy Acked-by: Borislav Petkov Acked-by: Michael Ellerman (powerpc) Signed-off-by: Daniel Thompson

kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()

2018-12-30T08:28:02Z

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() NOTE: In this patch we will still get into trouble if we try to round up a CPU that failed to round up before. We'll try to round it up again and potentially hang when we try to grab the csd lock. That's not new behavior but we'll still try to do better in a future patch. Suggested-by: Daniel Thompson Signed-off-by: Douglas Anderson Cc: Vineet Gupta Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Richard Kuo Cc: Ralf Baechle Cc: Paul Burton Cc: James Hogan Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Yoshinori Sato Cc: Rich Felker Cc: "David S. Miller" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Acked-by: Will Deacon Signed-off-by: Daniel Thompson

kgdb: Remove irq flags from roundup

2018-12-30T08:24:21Z

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 Cc: Vineet Gupta Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Richard Kuo Cc: Ralf Baechle Cc: Paul Burton Cc: James Hogan Cc: Benjamin Herrenschmidt Cc: Paul Mackerras Cc: Michael Ellerman Cc: Yoshinori Sato Cc: Rich Felker Cc: "David S. Miller" Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: "H. Peter Anvin" Acked-by: Will Deacon Signed-off-by: Daniel Thompson

kgdb: Remove "weak" from kgdb_arch_pc() declaration

2014-10-22T22:14:04Z

kernel/debug/debug_core.c provides a default kgdb_arch_pc() definition explicitly marked "weak". Several architectures provide their own definitions intended to override the default, but the "weak" attribute on the declaration applied to the arch definitions as well, so the linker chose one based on link order (see 10629d711ed7 ("PCI: Remove __weak annotation from pcibios_get_phb_of_node decl")). Remove the "weak" attribute from the declaration so we always prefer a non-weak definition over the weak one, independent of link order. Fixes: 688b744d8bc8 ("kgdb: fix signedness mixmatches, add statics, add declaration to header") Tested-by: Vineet Gupta # for ARC build Signed-off-by: Bjorn Helgaas Reviewed-by: Harvey Harrison

kgdb/kdb: Fix no KDB config problem

2014-01-25T07:55:09Z

Some code added to the debug_core module had KDB dependencies that it shouldn't have. Move the KDB dependent REASON back to the caller to remove the dependency in the debug core code. Update the call from the UV NMI handler to conform to the new interface. Signed-off-by: Mike Travis Reviewed-by: Hedi Berriche Cc: Russ Anderson Cc: Jason Wessel Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Link: http://lkml.kernel.org/r/20140114162551.318251993@asylum.americas.sgi.com Signed-off-by: Ingo Molnar

kdb: Add support for external NMI handler to call KGDB/KDB

2013-10-03T16:47:54Z

This patch adds a kgdb_nmicallin() interface that can be used by external NMI handlers to call the KGDB/KDB handler. The primary need for this is for those types of NMI interrupts where all the CPUs have already received the NMI signal. Therefore no send_IPI(NMI) is required, and in fact it will cause a 2nd unhandled NMI to occur. This generates the "Dazed and Confuzed" messages. Since all the CPUs are getting the NMI at roughly the same time, it's not guaranteed that the first CPU that hits the NMI handler will manage to enter KGDB and set the dbg_master_lock before the slaves start entering. The new argument "send_ready" was added for KGDB to signal the NMI handler to release the slave CPUs for entry into KGDB. Signed-off-by: Mike Travis Acked-by: Jason Wessel Reviewed-by: Dimitri Sivanich Reviewed-by: Hedi Berriche Cc: Peter Zijlstra Cc: Paul Mackerras Cc: Arnaldo Carvalho de Melo Link: http://lkml.kernel.org/r/20131002151417.928886849@asylum.americas.sgi.com Signed-off-by: Ingo Molnar

kgdb: remove #include from kgdb.h

2013-02-04T23:35:26Z

There's no reason kgdb.h itself needs to include the 8250 serial port header file. So push it down to the _very_ limited number of individual drivers that need the values in that file, and fix up the places where people really wanted serial_core.h and platform_device.h. Signed-off-by: Greg Kroah-Hartman

tty/serial: Add kgdb_nmi driver

2012-09-26T20:52:36Z

This special driver makes it possible to temporary use NMI debugger port as a normal console by issuing 'nmi_console' command (assuming that the port is attached to KGDB). Unlike KDB's disable_nmi command, with this driver you are always able to go back to the debugger using KGDB escape sequence ($3#33). This is because this console driver processes the input in NMI context, and thus is able to intercept the magic sequence. Note that since the console interprets input and uses polling communication methods, for things like PPP it is still better to fully detach debugger port from the KGDB NMI (i.e. disable_nmi), and use raw console. Usually, to enter the debugger one have to type the magic sequence, so initially the kernel will print the following prompt on the NMI debugger console: Type $3#33 to enter the debugger> For convenience, there is a kgdb_fiq.knock kernel command line option, when set to 0, this turns the special command to just a return key press, so the kernel will be printing this: Hit to enter the debugger> This is more convenient for long debugging sessions, although it makes nmi_console feature somewhat useless. And for the cases when NMI connected to a dedicated button, the knocking can be disabled altogether by setting kgdb_fiq.knock to -1. Suggested-by: Colin Cross Signed-off-by: Anton Vorontsov Acked-by: Alan Cox Acked-by: Jason Wessel Signed-off-by: Greg Kroah-Hartman

kernel/debug: Mask KGDB NMI upon entry

2012-09-26T20:42:25Z

The new arch callback should manage NMIs that usually cause KGDB to enter. That is, not all NMIs should be enabled/disabled, but only those that issue kgdb_handle_exception(). We must mask it as serial-line interrupt can be used as an NMI, so if the original KGDB-entry cause was say a breakpoint, then every input to KDB console will cause KGDB to reenter, which we don't want. Signed-off-by: Anton Vorontsov Acked-by: Jason Wessel Signed-off-by: Greg Kroah-Hartman

x86,kgdb: Fix DEBUG_RODATA limitation using text_poke()

2012-03-29T22:41:25Z

There has long been a limitation using software breakpoints with a kernel compiled with CONFIG_DEBUG_RODATA going back to 2.6.26. For this particular patch, it will apply cleanly and has been tested all the way back to 2.6.36. The kprobes code uses the text_poke() function which accommodates writing a breakpoint into a read-only page. The x86 kgdb code can solve the problem similarly by overriding the default breakpoint set/remove routines and using text_poke() directly. The x86 kgdb code will first attempt to use the traditional probe_kernel_write(), and next try using a the text_poke() function. The break point install method is tracked such that the correct break point removal routine will get called later on. Cc: x86@kernel.org Cc: Thomas Gleixner Cc: Ingo Molnar Cc: H. Peter Anvin Cc: stable@vger.kernel.org # >= 2.6.36 Inspried-by: Masami Hiramatsu Signed-off-by: Jason Wessel