@@ -297,6 +297,7 @@ choice
config ARCH_MULTIPLATFORM
bool "Allow multiple platforms to be selected"
depends on MMU
+ select ARCH_MIGHT_HAVE_KGDB_FIQ
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARM_HAS_SG_CHAIN
select ARM_PATCH_PHYS_VIRT
@@ -346,6 +347,7 @@ config ARCH_REALVIEW
config ARCH_VERSATILE
bool "ARM Ltd. Versatile family"
+ select ARCH_MIGHT_HAVE_KGDB_FIQ
select ARCH_WANT_OPTIONAL_GPIOLIB
select ARM_AMBA
select ARM_TIMER_SP804
@@ -2,6 +2,24 @@ menu "Kernel hacking"
source "lib/Kconfig.debug"
+config ARCH_MIGHT_HAVE_KGDB_FIQ
+ bool
+
+config KGDB_FIQ
+ bool "KGDB FIQ support"
+ depends on KGDB_KDB && ARCH_MIGHT_HAVE_KGDB_FIQ && !THUMB2_KERNEL
+ select FIQ
+ help
+ The FIQ debugger may be used to debug situations when the
+ kernel stuck in uninterruptable sections, e.g. the kernel
+ infinitely loops or deadlocked in an interrupt or with
+ interrupts disabled.
+
+ By default KGDB FIQ is disabled at runtime, but can be
+ enabled with kgdb_fiq.enable=1 kernel command line option.
+
+ If unsure, say N.
+
config ARM_PTDUMP
bool "Export kernel pagetable layout to userspace via debugfs"
depends on DEBUG_KERNEL
@@ -11,7 +11,9 @@
#define __ARM_KGDB_H__
#include <linux/ptrace.h>
+#include <linux/linkage.h>
#include <asm/opcodes.h>
+#include <asm/exception.h>
/*
* GDB assumes that we're a user process being debugged, so
@@ -48,6 +50,11 @@ static inline void arch_kgdb_breakpoint(void)
extern void kgdb_handle_bus_error(void);
extern int kgdb_fault_expected;
+extern char kgdb_fiq_handler;
+extern char kgdb_fiq_handler_end;
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs);
+extern int kgdb_register_fiq(unsigned int fiq);
+
#endif /* !__ASSEMBLY__ */
/*
@@ -68,6 +68,7 @@ endif
obj-$(CONFIG_OABI_COMPAT) += sys_oabi-compat.o
obj-$(CONFIG_ARM_THUMBEE) += thumbee.o
obj-$(CONFIG_KGDB) += kgdb.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq_entry.o kgdb_fiq.o
obj-$(CONFIG_ARM_UNWIND) += unwind.o
obj-$(CONFIG_HAVE_TCM) += tcm.o
obj-$(CONFIG_OF) += devtree.o
new file mode 100644
@@ -0,0 +1,127 @@
+/*
+ * KGDB FIQ
+ *
+ * Copyright 2010 Google, Inc.
+ * Arve Hjønnevåg <arve@android.com>
+ * Colin Cross <ccross@android.com>
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/errno.h>
+#include <linux/hardirq.h>
+#include <linux/atomic.h>
+#include <linux/kdb.h>
+#include <linux/kgdb.h>
+#include <asm/fiq.h>
+#include <asm/exception.h>
+
+static int kgdb_fiq_enabled;
+module_param_named(enable, kgdb_fiq_enabled, int, 0600);
+MODULE_PARM_DESC(enable, "set to 1 to enable FIQ KGDB");
+
+static unsigned int kgdb_fiq;
+
+struct fiq_stack {
+ u32 fiq[3];
+} ____cacheline_aligned;
+
+static struct fiq_stack stacks[NR_CPUS];
+
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs)
+{
+ if (kgdb_nmi_poll_knock()) {
+ nmi_enter();
+ kgdb_handle_exception(1, 0, 0, regs);
+ nmi_exit();
+ }
+
+ eoi_fiq(kgdb_fiq);
+}
+
+static struct fiq_handler kgdb_fiq_desc = {
+ .name = "kgdb",
+};
+
+static long kgdb_fiq_setup_stack(void *info)
+{
+ struct pt_regs regs;
+
+ regs.ARM_sp = (unsigned long) stacks[smp_processor_id()].fiq;
+ set_fiq_regs(®s);
+
+ return 0;
+}
+
+/**
+ * kgdb_fiq_enable_nmi - Manage NMI-triggered entry to KGDB
+ * @on: Flag to either enable or disable an NMI
+ *
+ * This function manages NMIs that usually cause KGDB to enter. That is, not
+ * all NMIs should be enabled or disabled, but only those that issue
+ * kgdb_handle_exception().
+ *
+ * The call counts disable requests, and thus allows to nest disables. But
+ * trying to enable already enabled NMI is an error.
+ */
+static void kgdb_fiq_enable_nmi(bool on)
+{
+ static atomic_t cnt;
+ int ret;
+
+ ret = atomic_add_return(on ? 1 : -1, &cnt);
+
+ /*
+ * There should be only one instance that calls this function
+ * in "enable, disable" order. All other users must call
+ * disable first, then enable. If not, something is wrong.
+ */
+ if (WARN_ON(ret > 1 && on))
+ return;
+
+ if (ret > 0)
+ enable_fiq(kgdb_fiq);
+ else
+ disable_fiq(kgdb_fiq);
+}
+
+int kgdb_register_fiq(unsigned int fiq)
+{
+ int err;
+ int cpu;
+
+ if (!kgdb_fiq_enabled)
+ return -ENODEV;
+
+ if (!has_fiq(fiq)) {
+ pr_warn(
+ "%s: Cannot register %u (no FIQ with this number)\n",
+ __func__, fiq);
+ return -ENODEV;
+ }
+
+ kgdb_fiq = fiq;
+
+ err = claim_fiq(&kgdb_fiq_desc);
+ if (err) {
+ pr_warn("%s: unable to claim fiq", __func__);
+ return err;
+ }
+
+ for_each_possible_cpu(cpu)
+ work_on_cpu(cpu, kgdb_fiq_setup_stack, NULL);
+
+ set_fiq_handler(&kgdb_fiq_handler,
+ &kgdb_fiq_handler_end - &kgdb_fiq_handler);
+
+ arch_kgdb_ops.enable_nmi = kgdb_fiq_enable_nmi;
+ return 0;
+}
new file mode 100644
@@ -0,0 +1,130 @@
+/*
+ * KGDB FIQ entry
+ *
+ * Copyright 1996,1997,1998 Russell King.
+ * Copyright 2012 Linaro Ltd.
+ * Anton Vorontsov <anton.vorontsov@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/memory.h>
+#include <asm/unwind.h>
+#include "entry-header.S"
+
+ .text
+
+@ This is needed for usr_entry/alignment_trap
+.LCcralign:
+ .long cr_alignment
+.LCdohandle:
+ .long kgdb_fiq_do_handle
+
+ .macro fiq_handler
+ ldr r1, =.LCdohandle
+ mov r0, sp
+ adr lr, BSYM(9997f)
+ ldr pc, [r1]
+9997:
+ .endm
+
+/*
+ * svc_exit_via_fiq
+ *
+ * This macro acts in a similar manner to svc_exit but switches to FIQ
+ * mode to restore the final part of the register state.
+ *
+ * We cannot use the normal svc_exit procedure because that would
+ * clobber spsr_svc (FIQ could be delivered during the first few instructions
+ * of vector_swi meaning its contents have not been saved anywhere).
+ */
+ .macro svc_exit_via_fiq, rpsr
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ tst \rpsr, #PSR_I_BIT
+ bleq trace_hardirqs_on
+#endif
+
+ mov r0, sp
+ ldmib r0, {r1 - r14} @ abort is deadly from here onward (it will
+ @ clobber state restored below)
+ msr cpsr_c, #FIQ_MODE | PSR_I_BIT | PSR_F_BIT
+ add r8, r0, #S_PC
+ ldr r9, [r0, #S_PSR]
+ msr spsr_cxsf, r9
+ ldr r0, [r0, #S_R0]
+ ldmia r8, {pc}^
+ .endm
+
+ .align 5
+__fiq_svc:
+ svc_entry
+ fiq_handler
+ svc_exit_via_fiq r5
+ UNWIND(.fnend )
+ENDPROC(__fiq_svc)
+ .ltorg
+
+ .align 5
+__fiq_abt:
+ svc_entry
+
+ msr cpsr_c, #ABT_MODE | PSR_I_BIT | PSR_F_BIT
+ mov r0, lr @ Save lr_abt
+ mrs r1, spsr @ Save spsr_abt, abort is now safe
+ msr cpsr_c, #SVC_MODE | PSR_I_BIT | PSR_F_BIT
+ push {r0 - r1}
+
+ fiq_handler
+
+ pop {r0 - r1}
+ msr cpsr_c, #ABT_MODE | PSR_I_BIT | PSR_F_BIT
+ mov lr, r0 @ Restore lr_abt, abort is unsafe
+ msr spsr_cxsf, r1 @ Restore spsr_abt
+ msr cpsr_c, #SVC_MODE | PSR_I_BIT | PSR_F_BIT
+
+ svc_exit_via_fiq r5
+ UNWIND(.fnend )
+ENDPROC(__fiq_svc)
+ .ltorg
+
+ .align 5
+__fiq_usr:
+ usr_entry
+ kuser_cmpxchg_check
+ fiq_handler
+ get_thread_info tsk
+ mov why, #0
+ b ret_to_user_from_irq
+ UNWIND(.fnend )
+ENDPROC(__fiq_usr)
+ .ltorg
+
+ .global kgdb_fiq_handler
+kgdb_fiq_handler:
+
+ vector_stub fiq, FIQ_MODE, 4
+
+ .long __fiq_usr @ 0 (USR_26 / USR_32)
+ .long __fiq_svc @ 1 (FIQ_26 / FIQ_32)
+ .long __fiq_svc @ 2 (IRQ_26 / IRQ_32)
+ .long __fiq_svc @ 3 (SVC_26 / SVC_32)
+ .long __fiq_svc @ 4
+ .long __fiq_svc @ 5
+ .long __fiq_svc @ 6
+ .long __fiq_abt @ 7
+ .long __fiq_svc @ 8
+ .long __fiq_svc @ 9
+ .long __fiq_svc @ a
+ .long __fiq_svc @ b
+ .long __fiq_svc @ c
+ .long __fiq_svc @ d
+ .long __fiq_svc @ e
+ .long __fiq_svc @ f
+
+ .global kgdb_fiq_handler_end
+kgdb_fiq_handler_end: