linux/arch/arm/kernel
Douglas Anderson 3cd99ac355 kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function()
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 <daniel.thompson@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Rich Felker <dalias@libc.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
2018-12-30 08:28:02 +00:00
..
.gitignore
arch_timer.c
armksyms.c ARM: 8788/1: ftrace: remove old mcount support 2018-09-19 10:44:50 +01:00
asm-offsets.c include/linux/compiler*.h: make compiler-*.h mutually exclusive 2018-08-22 17:31:34 -07:00
atags_compat.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
atags_parse.c ARM: better diagnostics with missing/corrupt dtb 2017-09-29 13:57:21 +01:00
atags_proc.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
atags.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bios32.c PCI: Remove PCI_REASSIGN_ALL_RSRC use on arm and arm64 2017-12-18 23:07:43 -06:00
bugs.c ARM: clean up per-processor check_bugs method call 2018-11-12 10:51:01 +00:00
cpuidle.c ARM: Convert to using %pOF instead of full_name 2017-08-16 22:25:30 +02:00
crash_dump.c
debug.S Merge branches 'fixes', 'misc' and 'sa1111-for-next' into for-next 2017-11-08 19:42:43 +00:00
devtree.c mm: remove include/linux/bootmem.h 2018-10-31 08:54:16 -07:00
dma-isa.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
dma.c proc: introduce proc_create_single{,_data} 2018-05-16 07:23:35 +02:00
early_printk.c ARM: 8705/1: early_printk: use printascii() rather than printch() 2017-10-12 11:29:29 +01:00
efi.c ARM/efi: Apply strict permissions for UEFI Runtime Services regions 2016-04-28 11:33:53 +02:00
elf.c Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-11-16 12:50:35 -08:00
entry-armv.S ARM: Convert to GENERIC_IRQ_MULTI_HANDLER 2018-08-03 12:14:08 +02:00
entry-common.S ARM: 8802/1: Call syscall_trace_exit even when system call skipped 2018-10-10 13:53:12 +01:00
entry-ftrace.S ARM: 8788/1: ftrace: remove old mcount support 2018-09-19 10:44:50 +01:00
entry-header.S ARM: spectre-v1: fix syscall entry 2018-05-31 23:27:26 +01:00
entry-v7m.S ARM: rename S_FRAME_SIZE to PT_REGS_SIZE 2016-06-22 19:54:28 +01:00
fiq.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fiqasm.S
ftrace.c ARM: function_graph: Simplify with function_graph_enter() 2018-11-27 20:29:52 -05:00
head-common.S ARM: make lookup_processor_type() non-__init 2018-11-12 10:51:01 +00:00
head-inflate-data.c ARM: XIP kernel: store .data compressed in ROM 2017-09-10 19:34:53 -04:00
head-nommu.S Merge branches 'fixes', 'misc' and 'spectre' into for-linus 2018-08-13 16:28:50 +01:00
head.S ARM: align .data section 2017-08-14 16:22:55 +01:00
hibernate.c ARM: use virt_to_idmap() for soft_restart() 2016-02-08 15:48:32 +00:00
hw_breakpoint.c perf/arch/arm: Implement hw_breakpoint_arch_parse() 2018-06-26 09:07:56 +02:00
hyp-stub.S ARM: align .data section 2017-08-14 16:22:55 +01:00
insn.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
io.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
irq.c ARM: Convert to GENERIC_IRQ_MULTI_HANDLER 2018-08-03 12:14:08 +02:00
isa.c
iwmmxt.S ARM: align .data section 2017-08-14 16:22:55 +01:00
jump_label.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kgdb.c kgdb: Fix kgdb_roundup_cpus() for arches who used smp_call_function() 2018-12-30 08:28:02 +00:00
machine_kexec.c ARM: kexec: record parent context registers for non-crash CPUs 2018-05-19 11:35:56 +01:00
Makefile ARM: bugs: prepare processor bug infrastructure 2018-05-31 10:39:18 +01:00
module-plts.c ARM: 8662/1: module: split core and init PLT sections 2017-03-17 10:01:28 +00:00
module.c ARM: Silence first allocation with CONFIG_ARM_MODULE_PLTS=y 2017-05-11 14:43:31 +01:00
module.lds License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
opcodes.c
paravirt.c x86/paravirt: Use a single ops structure 2018-09-03 16:50:35 +02:00
patch.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf_callchain.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
perf_event_v6.c arm_pmu: Tidy up clear_event_idx call backs 2018-07-10 18:19:02 +01:00
perf_event_v7.c arm_pmu: Tidy up clear_event_idx call backs 2018-07-10 18:19:02 +01:00
perf_event_xscale.c arm_pmu: Tidy up clear_event_idx call backs 2018-07-10 18:19:02 +01:00
perf_regs.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
pj4-cp0.c ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode 2016-01-04 11:12:10 +00:00
process.c mm: zero out the vma in vma_init() 2018-08-22 10:52:44 -07:00
psci_smp.c ARM: use const and __initconst for smp_operations 2015-12-01 22:17:45 +01:00
ptrace.c signal/arm: Use force_sig_fault where appropriate 2018-09-27 21:57:39 +02:00
reboot.c ARM: soft-reboot into same mode that we entered the kernel 2017-04-09 07:49:24 -07:00
reboot.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
relocate_kernel.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
return_address.c ARM: 8328/1: remove empty preprocessor #else branch 2015-03-28 16:54:53 +00:00
setup.c Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm 2018-11-18 10:45:09 -08:00
signal.c Merge branches 'fixes', 'misc' and 'spectre' into for-next 2018-10-10 13:53:33 +01:00
signal.h ARM: signal handling support for FDPIC_FUNCPTRS functions 2017-09-10 19:31:46 -04:00
sigreturn_codes.S ARM: signal handling support for FDPIC_FUNCPTRS functions 2017-09-10 19:31:46 -04:00
sleep.S License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
smccc-call.S arm: kernel: Add SMC structure parameter 2017-02-03 18:46:33 +00:00
smp_scu.c ARM: smp_scu: allow the platform code to read the SCU CPU status 2017-10-29 08:29:30 -07:00
smp_tlb.c ARM: 8613/1: Fix the uaccess crash on PB11MPCore 2017-01-16 17:30:46 +00:00
smp_twd.c clocksource/drivers: Rename CLOCKSOURCE_OF_DECLARE to TIMER_OF_DECLARE 2017-06-14 11:58:45 +02:00
smp.c Merge branch 'spectre' of git://git.armlinux.org.uk/~rmk/linux-arm 2018-11-18 10:45:09 -08:00
stacktrace.c ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code 2017-12-17 22:14:21 +00:00
suspend.c ARM: bugs: hook processor bug checking into SMP and suspend paths 2018-05-31 10:39:29 +01:00
swp_emulate.c signal/arm: Push siginfo generation into arm_notify_die 2018-09-27 21:55:30 +02:00
sys_arm.c mm: add ksys_fadvise64_64() helper; remove in-kernel call to sys_fadvise64_64() 2018-04-02 20:16:10 +02:00
sys_oabi-compat.c Merge branches 'fixes', 'misc' and 'spectre' into for-next 2018-10-10 13:53:33 +01:00
tcm.c ARM: 8388/1: tcm: Don't crash when TCM banks are protected by TrustZone 2015-06-06 10:37:28 +01:00
thumbee.c ARM: convert printk(KERN_* to pr_* 2014-11-21 15:24:50 +00:00
time.c ARM/time: Remove read_boot_clock64() 2018-07-20 00:02:41 +02:00
topology.c ARM: topology: remove unneeded check for /cpus node 2018-09-28 14:25:58 -05:00
traps.c signal/arm: Push siginfo generation into arm_notify_die 2018-09-27 21:55:30 +02:00
unwind.c
v7m.c
vdso.c ARM: 8748/1: mm: Define vdso_start, vdso_end as array 2018-03-24 14:27:49 +00:00
vmlinux-xip.lds.S vmlinux.lds.h: Move LSM_TABLE into INIT_DATA 2018-10-10 20:40:21 -07:00
vmlinux.lds.h vmlinux.lds.h: Fix incomplete .text.exit discards 2018-10-12 08:54:58 +11:00
vmlinux.lds.S ARM: 8757/1: NOMMU: Support PMSAv8 MPU 2018-05-19 11:53:46 +01:00
xscale-cp0.c ARM: make xscale iwmmxt code multiplatform aware 2015-12-01 21:44:24 +01:00