* [PATCH 1/8] kernel/debug: Make use of KGDB_REASON_NMI
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 2/8] kernel/debug: Mask KGDB NMI upon entry Anton Vorontsov
` (6 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
Currently kernel never set KGDB_REASON_NMI. We do now, when we enter
KGDB/KDB from an NMI.
This is not to be confused with kgdb_nmicallback(), NMI callback is
an entry for the slave CPUs during CPUs roundup, but REASON_NMI is the
entry for the master CPU.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
kernel/debug/kdb/kdb_debugger.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 8b68ce7..be7b33b 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -12,6 +12,7 @@
#include <linux/kdb.h>
#include <linux/kdebug.h>
#include <linux/export.h>
+#include <linux/hardirq.h>
#include "kdb_private.h"
#include "../debug_core.h"
@@ -52,6 +53,9 @@ int kdb_stub(struct kgdb_state *ks)
if (atomic_read(&kgdb_setting_breakpoint))
reason = KDB_REASON_KEYBOARD;
+ if (in_nmi())
+ reason = KDB_REASON_NMI;
+
for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
if ((bp->bp_enabled) && (bp->bp_addr == addr)) {
reason = KDB_REASON_BREAK;
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 2/8] kernel/debug: Mask KGDB NMI upon entry
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
2012-07-13 10:16 ` [PATCH 1/8] kernel/debug: Make use of KGDB_REASON_NMI Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 3/8] ARM: Move some macros from entry-armv to entry-header Anton Vorontsov
` (5 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
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 <anton.vorontsov@linaro.org>
---
include/linux/kgdb.h | 9 +++++++++
kernel/debug/debug_core.c | 12 +++++++++++-
2 files changed, 20 insertions(+), 1 deletion(-)
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index c4d2fc1..47e739e 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -221,6 +221,15 @@ extern int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt);
*/
extern void kgdb_arch_late(void);
+/**
+ * kgdb_arch_enable_nmi - Enable or disable KGDB-entry NMI
+ * @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().
+ */
+extern void kgdb_arch_enable_nmi(bool on);
/**
* struct kgdb_arch - Describe architecture specific values.
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0557f24..e285600 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -214,6 +214,10 @@ int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
return 0;
}
+void __weak kgdb_arch_enable_nmi(bool on)
+{
+}
+
/*
* Some architectures need cache flushes when we set/clear a
* breakpoint:
@@ -672,6 +676,9 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
{
struct kgdb_state kgdb_var;
struct kgdb_state *ks = &kgdb_var;
+ int ret;
+
+ kgdb_arch_enable_nmi(0);
ks->cpu = raw_smp_processor_id();
ks->ex_vector = evector;
@@ -685,7 +692,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
if (kgdb_info[ks->cpu].enter_kgdb != 0)
return 0;
- return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+ ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+
+ kgdb_arch_enable_nmi(1);
+ return ret;
}
int kgdb_nmicallback(int cpu, void *regs)
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 3/8] ARM: Move some macros from entry-armv to entry-header
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
2012-07-13 10:16 ` [PATCH 1/8] kernel/debug: Make use of KGDB_REASON_NMI Anton Vorontsov
2012-07-13 10:16 ` [PATCH 2/8] kernel/debug: Mask KGDB NMI upon entry Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 4/8] ARM: Add KGDB/KDB FIQ debugger generic code Anton Vorontsov
` (4 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
Just move the macros into header file as we would want to use them for
KGDB FIQ entry code.
The following macros were moved:
- svc_entry
- usr_entry
- kuser_cmpxchg_check
- vector_stub
To make kuser_cmpxchg_check actually work across different files, we
also have to make kuser_cmpxchg64_fixup global.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/kernel/entry-armv.S | 167 +--------------------------------------
| 170 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 171 insertions(+), 166 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 0d1851c..6aeb9b8 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -136,57 +136,6 @@ common_invalid:
b bad_mode
ENDPROC(__und_invalid)
-/*
- * SVC mode handlers
- */
-
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
-#define SPFIX(code...) code
-#else
-#define SPFIX(code...)
-#endif
-
- .macro svc_entry, stack_hole=0
- UNWIND(.fnstart )
- UNWIND(.save {r0 - pc} )
- sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
-#ifdef CONFIG_THUMB2_KERNEL
- SPFIX( str r0, [sp] ) @ temporarily saved
- SPFIX( mov r0, sp )
- SPFIX( tst r0, #4 ) @ test original stack alignment
- SPFIX( ldr r0, [sp] ) @ restored
-#else
- SPFIX( tst sp, #4 )
-#endif
- SPFIX( subeq sp, sp, #4 )
- stmia sp, {r1 - r12}
-
- ldmia r0, {r3 - r5}
- add r7, sp, #S_SP - 4 @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
- add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
- SPFIX( addeq r2, r2, #4 )
- str r3, [sp, #-4]! @ save the "real" r0 copied
- @ from the exception stack
-
- mov r3, lr
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r2 - sp_svc
- @ r3 - lr_svc
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- stmia r7, {r2 - r6}
-
-#ifdef CONFIG_TRACE_IRQFLAGS
- bl trace_hardirqs_off
-#endif
- .endm
-
.align 5
__dabt_svc:
svc_entry
@@ -328,71 +277,8 @@ ENDPROC(__pabt_svc)
/*
* User mode handlers
- *
- * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
*/
-#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
-#error "sizeof(struct pt_regs) must be a multiple of 8"
-#endif
-
- .macro usr_entry
- UNWIND(.fnstart )
- UNWIND(.cantunwind ) @ don't unwind the user space
- sub sp, sp, #S_FRAME_SIZE
- ARM( stmib sp, {r1 - r12} )
- THUMB( stmia sp, {r0 - r12} )
-
- ldmia r0, {r3 - r5}
- add r0, sp, #S_PC @ here for interlock avoidance
- mov r6, #-1 @ "" "" "" ""
-
- str r3, [sp] @ save the "real" r0 copied
- @ from the exception stack
-
- @
- @ We are now ready to fill in the remaining blanks on the stack:
- @
- @ r4 - lr_<exception>, already fixed up for correct return/restart
- @ r5 - spsr_<exception>
- @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
- @
- @ Also, separately save sp_usr and lr_usr
- @
- stmia r0, {r4 - r6}
- ARM( stmdb r0, {sp, lr}^ )
- THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
-
- @
- @ Enable the alignment trap while in kernel mode
- @
- alignment_trap r0
-
- @
- @ Clear FP to mark the first stack frame
- @
- zero_fp
-
-#ifdef CONFIG_IRQSOFF_TRACER
- bl trace_hardirqs_off
-#endif
- .endm
-
- .macro kuser_cmpxchg_check
-#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
-#ifndef CONFIG_MMU
-#warning "NPTL on non MMU needs fixing"
-#else
- @ Make sure our user space atomic helper is restarted
- @ if it was interrupted in a critical region. Here we
- @ perform a quick test inline since it should be false
- @ 99.9999% of the time. The rest is done out of line.
- cmp r4, #TASK_SIZE
- blhs kuser_cmpxchg64_fixup
-#endif
-#endif
- .endm
-
.align 5
__dabt_usr:
usr_entry
@@ -813,6 +699,7 @@ __kuser_cmpxchg64: @ 0xffff0f60
ldmfd sp!, {r4, r5, r6, pc}
.text
+ .global kuser_cmpxchg64_fixup
kuser_cmpxchg64_fixup:
@ Called from kuser_cmpxchg_fixup.
@ r4 = address of interrupted insn (must be preserved).
@@ -943,58 +830,6 @@ __kuser_helper_end:
THUMB( .thumb )
-/*
- * Vector stubs.
- *
- * This code is copied to 0xffff0200 so we can use branches in the
- * vectors, rather than ldr's. Note that this code must not
- * exceed 0x300 bytes.
- *
- * Common stub entry macro:
- * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
- *
- * SP points to a minimal amount of processor-private memory, the address
- * of which is copied into r0 for the mode specific abort handler.
- */
- .macro vector_stub, name, mode, correction=0
- .align 5
-
-vector_\name:
- .if \correction
- sub lr, lr, #\correction
- .endif
-
- @
- @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
- @ (parent CPSR)
- @
- stmia sp, {r0, lr} @ save r0, lr
- mrs lr, spsr
- str lr, [sp, #8] @ save spsr
-
- @
- @ Prepare for SVC32 mode. IRQs remain disabled.
- @
- mrs r0, cpsr
- eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
- msr spsr_cxsf, r0
-
- @
- @ the branch table must immediately follow this code
- @
- and lr, lr, #0x0f
- THUMB( adr r0, 1f )
- THUMB( ldr lr, [r0, lr, lsl #2] )
- mov r0, sp
- ARM( ldr lr, [pc, lr, lsl #2] )
- movs pc, lr @ branch to handler in SVC mode
-ENDPROC(vector_\name)
-
- .align 2
- @ handler addresses follow this label
-1:
- .endm
-
.globl __stubs_start
__stubs_start:
/*
--git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 9a8531e..c3c09ac 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -73,6 +73,109 @@
msr cpsr_c, \rtemp @ switch back to the SVC mode
.endm
+/*
+ * Vector stubs.
+ *
+ * This code is copied to 0xffff0200 so we can use branches in the
+ * vectors, rather than ldr's. Note that this code must not
+ * exceed 0x300 bytes.
+ *
+ * Common stub entry macro:
+ * Enter in IRQ mode, spsr = SVC/USR CPSR, lr = SVC/USR PC
+ *
+ * SP points to a minimal amount of processor-private memory, the address
+ * of which is copied into r0 for the mode specific abort handler.
+ */
+ .macro vector_stub, name, mode, correction=0
+ .align 5
+
+vector_\name:
+ .if \correction
+ sub lr, lr, #\correction
+ .endif
+
+ @
+ @ Save r0, lr_<exception> (parent PC) and spsr_<exception>
+ @ (parent CPSR)
+ @
+ stmia sp, {r0, lr} @ save r0, lr
+ mrs lr, spsr
+ str lr, [sp, #8] @ save spsr
+
+ @
+ @ Prepare for SVC32 mode. IRQs remain disabled.
+ @
+ mrs r0, cpsr
+ eor r0, r0, #(\mode ^ SVC_MODE | PSR_ISETSTATE)
+ msr spsr_cxsf, r0
+
+ @
+ @ the branch table must immediately follow this code
+ @
+ and lr, lr, #0x0f
+ THUMB( adr r0, 1f )
+ THUMB( ldr lr, [r0, lr, lsl #2] )
+ mov r0, sp
+ ARM( ldr lr, [pc, lr, lsl #2] )
+ movs pc, lr @ branch to handler in SVC mode
+ENDPROC(vector_\name)
+
+ .align 2
+ @ handler addresses follow this label
+1:
+ .endm
+
+/*
+ * SVC mode handlers
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5)
+#define SPFIX(code...) code
+#else
+#define SPFIX(code...)
+#endif
+
+ .macro svc_entry, stack_hole=0
+ UNWIND(.fnstart )
+ UNWIND(.save {r0 - pc} )
+ sub sp, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+#ifdef CONFIG_THUMB2_KERNEL
+ SPFIX( str r0, [sp] ) @ temporarily saved
+ SPFIX( mov r0, sp )
+ SPFIX( tst r0, #4 ) @ test original stack alignment
+ SPFIX( ldr r0, [sp] ) @ restored
+#else
+ SPFIX( tst sp, #4 )
+#endif
+ SPFIX( subeq sp, sp, #4 )
+ stmia sp, {r1 - r12}
+
+ ldmia r0, {r3 - r5}
+ add r7, sp, #S_SP - 4 @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+ add r2, sp, #(S_FRAME_SIZE + \stack_hole - 4)
+ SPFIX( addeq r2, r2, #4 )
+ str r3, [sp, #-4]! @ save the "real" r0 copied
+ @ from the exception stack
+
+ mov r3, lr
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r2 - sp_svc
+ @ r3 - lr_svc
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ stmia r7, {r2 - r6}
+
+#ifdef CONFIG_TRACE_IRQFLAGS
+ bl trace_hardirqs_off
+#endif
+ .endm
+
#ifndef CONFIG_THUMB2_KERNEL
.macro svc_exit, rpsr
msr spsr_cxsf, \rpsr
@@ -164,6 +267,73 @@
#endif /* !CONFIG_THUMB2_KERNEL */
/*
+ * User mode handlers
+ *
+ * EABI note: sp_svc is always 64-bit aligned here, so should S_FRAME_SIZE
+ */
+
+#if defined(CONFIG_AEABI) && (__LINUX_ARM_ARCH__ >= 5) && (S_FRAME_SIZE & 7)
+#error "sizeof(struct pt_regs) must be a multiple of 8"
+#endif
+
+ .macro usr_entry
+ UNWIND(.fnstart )
+ UNWIND(.cantunwind ) @ don't unwind the user space
+ sub sp, sp, #S_FRAME_SIZE
+ ARM( stmib sp, {r1 - r12} )
+ THUMB( stmia sp, {r0 - r12} )
+
+ ldmia r0, {r3 - r5}
+ add r0, sp, #S_PC @ here for interlock avoidance
+ mov r6, #-1 @ "" "" "" ""
+
+ str r3, [sp] @ save the "real" r0 copied
+ @ from the exception stack
+
+ @
+ @ We are now ready to fill in the remaining blanks on the stack:
+ @
+ @ r4 - lr_<exception>, already fixed up for correct return/restart
+ @ r5 - spsr_<exception>
+ @ r6 - orig_r0 (see pt_regs definition in ptrace.h)
+ @
+ @ Also, separately save sp_usr and lr_usr
+ @
+ stmia r0, {r4 - r6}
+ ARM( stmdb r0, {sp, lr}^ )
+ THUMB( store_user_sp_lr r0, r1, S_SP - S_PC )
+
+ @
+ @ Enable the alignment trap while in kernel mode
+ @
+ alignment_trap r0
+
+ @
+ @ Clear FP to mark the first stack frame
+ @
+ zero_fp
+
+#ifdef CONFIG_IRQSOFF_TRACER
+ bl trace_hardirqs_off
+#endif
+ .endm
+
+ .macro kuser_cmpxchg_check
+#if !defined(CONFIG_CPU_32v6K) && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+#ifndef CONFIG_MMU
+#warning "NPTL on non MMU needs fixing"
+#else
+ @ Make sure our user space atomic helper is restarted
+ @ if it was interrupted in a critical region. Here we
+ @ perform a quick test inline since it should be false
+ @ 99.9999% of the time. The rest is done out of line.
+ cmp r4, #TASK_SIZE
+ blhs kuser_cmpxchg64_fixup
+#endif
+#endif
+ .endm
+
+/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - r0 to r6.
*
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 4/8] ARM: Add KGDB/KDB FIQ debugger generic code
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
` (2 preceding siblings ...)
2012-07-13 10:16 ` [PATCH 3/8] ARM: Move some macros from entry-armv to entry-header Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 5/8] ARM: kgdb_fiq: Implement knocking into KDB via escape command Anton Vorontsov
` (3 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
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 in runtime, but can be enabled with
kgdb_fiq.enable=1 kernel command line option.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/Kconfig | 18 ++++++++
arch/arm/include/asm/kgdb.h | 8 ++++
arch/arm/kernel/Makefile | 1 +
arch/arm/kernel/kgdb_fiq.c | 93 ++++++++++++++++++++++++++++++++++++++
arch/arm/kernel/kgdb_fiq_entry.S | 79 ++++++++++++++++++++++++++++++++
5 files changed, 199 insertions(+)
create mode 100644 arch/arm/kernel/kgdb_fiq.c
create mode 100644 arch/arm/kernel/kgdb_fiq_entry.S
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index a91009c..ae6ddf1 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -172,6 +172,24 @@ config GENERIC_ISA_DMA
config FIQ
bool
+config ARCH_MIGHT_HAVE_FIQ
+ bool
+
+config KGDB_FIQ
+ bool "KGDB/KDB FIQ debugger"
+ depends on KGDB_KDB && ARCH_MIGHT_HAVE_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 in runtime, but can be
+ enabled with kgdb_fiq.enable=1 kernel command line option.
+
+ If unsure, say N.
+
config NEED_RET_TO_USER
bool
diff --git a/arch/arm/include/asm/kgdb.h b/arch/arm/include/asm/kgdb.h
index 48066ce..807e547 100644
--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -11,6 +11,8 @@
#define __ARM_KGDB_H__
#include <linux/ptrace.h>
+#include <linux/linkage.h>
+#include <asm/exception.h>
/*
* GDB assumes that we're a user process being debugged, so
@@ -47,6 +49,12 @@ 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 __init kgdb_register_fiq(unsigned int mach_kgdb_fiq,
+ void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on),
+ bool (*mach_is_kgdb_fiq)(unsigned int irq));
#endif /* !__ASSEMBLY__ */
/*
diff --git a/arch/arm/kernel/Makefile b/arch/arm/kernel/Makefile
index 7ad2d5c..5aa079b 100644
--- a/arch/arm/kernel/Makefile
+++ b/arch/arm/kernel/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_ATAGS_PROC) += atags.o
obj-$(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
diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c
new file mode 100644
index 0000000..7ec9979
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq.c
@@ -0,0 +1,93 @@
+/*
+ * KGDB FIQ entry
+ *
+ * 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/hardirq.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;
+static void (*kgdb_enable_fiq)(unsigned int irq, bool on);
+static bool (*is_kgdb_fiq)(unsigned int irq);
+
+asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs)
+{
+ if (!is_kgdb_fiq(kgdb_fiq))
+ return;
+
+ nmi_enter();
+ kgdb_handle_exception(1, 0, 0, regs);
+ nmi_exit();
+}
+
+static struct fiq_handler kgdb_fiq_desc = {
+ .name = "kgdb",
+};
+
+static long kgdb_fiq_setup_stack(void *info)
+{
+ struct pt_regs regs;
+
+ regs.ARM_sp = __get_free_pages(GFP_KERNEL, THREAD_SIZE_ORDER) +
+ THREAD_START_SP;
+ WARN_ON(!regs.ARM_sp);
+
+ set_fiq_regs(®s);
+ return 0;
+}
+
+void kgdb_arch_enable_nmi(bool on)
+{
+ kgdb_enable_fiq(kgdb_fiq, on);
+}
+
+int __init kgdb_register_fiq(unsigned int mach_kgdb_fiq,
+ void (*mach_kgdb_enable_fiq)(unsigned int irq, bool on),
+ bool (*mach_is_kgdb_fiq)(unsigned int irq))
+{
+ int err;
+ int cpu;
+
+ if (!kgdb_fiq_enabled)
+ return -ENODEV;
+ if (kgdb_fiq)
+ return -EBUSY;
+
+ kgdb_fiq = mach_kgdb_fiq;
+ kgdb_enable_fiq = mach_kgdb_enable_fiq;
+ is_kgdb_fiq = mach_is_kgdb_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);
+
+ kgdb_arch_enable_nmi(1);
+ return 0;
+}
diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S
new file mode 100644
index 0000000..7be3726
--- /dev/null
+++ b/arch/arm/kernel/kgdb_fiq_entry.S
@@ -0,0 +1,79 @@
+/*
+ * 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
+
+ .align 5
+__fiq_svc:
+ svc_entry
+ fiq_handler
+ svc_exit r5 @ return from exception
+ 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_svc @ 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:
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 5/8] ARM: kgdb_fiq: Implement knocking into KDB via escape command
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
` (3 preceding siblings ...)
2012-07-13 10:16 ` [PATCH 4/8] ARM: Add KGDB/KDB FIQ debugger generic code Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 6/8] ARM: VIC: Add a couple of low-level FIQ management helpers Anton Vorontsov
` (2 subsequent siblings)
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
As Colin Cross noticed, serial ports could be noisy, so occasional
characters once in a while are possible. So, considering the noise
possibility, entering the debugger on any received byte is unacceptable
for production devices.
This changes KGDB FIQ behaviour in a such way so that we have to type the
GDB-protocol "$3#33" command to actually enter the debugger, the kernel
will print the following prompt:
Type $3#33 to enter the debugger.
This is the exactly the same command we use to escape from KGDB to KDB,
so it should be all pretty familiar.
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 <return> to enter the debugger.
Suggested-by: Colin Cross <ccross@android.com>
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/kernel/kgdb_fiq.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/arch/arm/kernel/kgdb_fiq.c b/arch/arm/kernel/kgdb_fiq.c
index 7ec9979..5308697 100644
--- a/arch/arm/kernel/kgdb_fiq.c
+++ b/arch/arm/kernel/kgdb_fiq.c
@@ -17,6 +17,7 @@
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/hardirq.h>
+#include <linux/kdb.h>
#include <linux/kgdb.h>
#include <asm/fiq.h>
#include <asm/exception.h>
@@ -25,6 +26,51 @@ 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 bool kgdb_fiq_knock = 1;
+module_param_named(knock, kgdb_fiq_knock, bool, 0600);
+MODULE_PARM_DESC(knock, "'$3#33' command must be used to enter the debugger");
+
+/*
+ * "Serial ports are often noisy, especially when muxed over another port (we
+ * often use serial over the headset connector). Noise on the async command
+ * line just causes characters that are ignored, on a command line that blocked
+ * execution noise would be catastrophic." -- Colin Cross
+ *
+ * So, this small function implements KGDB/KDB knocking on the serial line: we
+ * won't enter the debugger until we receive a known magic phrase (which is
+ * actually "$3#33", known as "escape to KDB" command. If knocking is disabled,
+ * just pressing the return key is enough to enter the debugger.
+ */
+static bool kgdb_fiq_poll_knock(void)
+{
+ static int n;
+ int c = -1;
+ get_char_func *getc;
+ const char *magic = "$3#33";
+ size_t m = strlen(magic);
+
+ for (getc = &kdb_poll_funcs[0]; *getc; ++getc) {
+ c = (*getc)();
+ if (c >= 0)
+ break;
+ }
+
+ if (!kgdb_fiq_knock && (c == '\r' || c == '\n')) {
+ return 1;
+ } else if (c == magic[n]) {
+ kdb_printf("%c", c);
+ n = (n + 1) % m;
+ if (!n)
+ return 1;
+ } else {
+ n = 0;
+ kdb_printf("\n%s %s to enter the debugger.\n",
+ kgdb_fiq_knock ? "Type" : "Hit",
+ kgdb_fiq_knock ? magic : "<return>");
+ }
+ return 0;
+}
+
static unsigned int kgdb_fiq;
static void (*kgdb_enable_fiq)(unsigned int irq, bool on);
static bool (*is_kgdb_fiq)(unsigned int irq);
@@ -33,6 +79,8 @@ asmlinkage void __exception_irq_entry kgdb_fiq_do_handle(struct pt_regs *regs)
{
if (!is_kgdb_fiq(kgdb_fiq))
return;
+ if (!kgdb_fiq_poll_knock())
+ return;
nmi_enter();
kgdb_handle_exception(1, 0, 0, regs);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 6/8] ARM: VIC: Add a couple of low-level FIQ management helpers
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
` (4 preceding siblings ...)
2012-07-13 10:16 ` [PATCH 5/8] ARM: kgdb_fiq: Implement knocking into KDB via escape command Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 7/8] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger Anton Vorontsov
2012-07-13 10:16 ` [PATCH 8/8] ARM: Get rid of .LCcralign local label usage in alignment_trap macro Anton Vorontsov
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
Just a couple of calls to manage VIC FIQ routing. We'll use them for
KGDB FIQ support on ARM Versatile machines.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/common/vic.c | 28 ++++++++++++++++++++++++++++
arch/arm/include/asm/hardware/vic.h | 2 ++
2 files changed, 30 insertions(+)
diff --git a/arch/arm/common/vic.c b/arch/arm/common/vic.c
index e0d5388..df2fc82 100644
--- a/arch/arm/common/vic.c
+++ b/arch/arm/common/vic.c
@@ -66,6 +66,34 @@ static struct vic_device vic_devices[CONFIG_ARM_VIC_NR];
static int vic_id;
+static void __iomem *vic_base(struct irq_data *d)
+{
+ return (void __iomem *)irq_data_get_irq_chip_data(d);
+}
+
+void vic_fiq_select(unsigned int irq, bool on)
+{
+ void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+ void __iomem *sel = base + VIC_INT_SELECT;
+ u32 msk = 1 << irq;
+ u32 val;
+
+ pr_debug("rerouting VIC vector %d to %s\n", irq, on ? "FIQ" : "IRQ");
+
+ val = readl(sel);
+ val &= ~msk;
+ if (on)
+ val |= msk;
+ writel(val, sel);
+}
+
+bool vic_is_fiq_rised(unsigned int irq)
+{
+ void __iomem *base = vic_base(&irq_to_desc(irq)->irq_data);
+
+ return readl(base + VIC_FIQ_STATUS) & (1 << irq);
+}
+
/**
* vic_init2 - common initialisation code
* @base: Base of the VIC.
diff --git a/arch/arm/include/asm/hardware/vic.h b/arch/arm/include/asm/hardware/vic.h
index e14af1a..2728975 100644
--- a/arch/arm/include/asm/hardware/vic.h
+++ b/arch/arm/include/asm/hardware/vic.h
@@ -52,6 +52,8 @@ void __vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources,
void vic_init(void __iomem *base, unsigned int irq_start, u32 vic_sources, u32 resume_sources);
int vic_of_init(struct device_node *node, struct device_node *parent);
void vic_handle_irq(struct pt_regs *regs);
+void vic_fiq_select(unsigned int irq, bool on);
+bool vic_is_fiq_rised(unsigned int irq);
#endif /* __ASSEMBLY__ */
#endif
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 7/8] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
` (5 preceding siblings ...)
2012-07-13 10:16 ` [PATCH 6/8] ARM: VIC: Add a couple of low-level FIQ management helpers Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
2012-07-13 10:16 ` [PATCH 8/8] ARM: Get rid of .LCcralign local label usage in alignment_trap macro Anton Vorontsov
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
If enabled, kernel will able to enter KGDB upon serial line activity on
UART ports.
Note that even with this patch and CONFIG_KGDB_FIQ is enabled, you still
need to pass kgdb_fiq.enable=1 kernel command line option, otherwise UART
will behave in a normal way.
By default UART0 is used, but this can be changed via kgdb_fiq.uart_num
kernel command line option.
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/Kconfig | 1 +
arch/arm/mach-versatile/Makefile | 1 +
arch/arm/mach-versatile/include/mach/irqs.h | 1 +
arch/arm/mach-versatile/kgdb_fiq.c | 31 +++++++++++++++++++++++++++
4 files changed, 34 insertions(+)
create mode 100644 arch/arm/mach-versatile/kgdb_fiq.c
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ae6ddf1..c0df1ba 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -311,6 +311,7 @@ config ARCH_VERSATILE
select ICST
select GENERIC_CLOCKEVENTS
select ARCH_WANT_OPTIONAL_GPIOLIB
+ select ARCH_MIGHT_HAVE_FIQ
select NEED_MACH_IO_H if PCI
select PLAT_VERSATILE
select PLAT_VERSATILE_CLCD
diff --git a/arch/arm/mach-versatile/Makefile b/arch/arm/mach-versatile/Makefile
index 81fa3fe..bfd761f 100644
--- a/arch/arm/mach-versatile/Makefile
+++ b/arch/arm/mach-versatile/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_ARCH_VERSATILE_PB) += versatile_pb.o
obj-$(CONFIG_MACH_VERSATILE_AB) += versatile_ab.o
obj-$(CONFIG_MACH_VERSATILE_DT) += versatile_dt.o
obj-$(CONFIG_PCI) += pci.o
+obj-$(CONFIG_KGDB_FIQ) += kgdb_fiq.o
diff --git a/arch/arm/mach-versatile/include/mach/irqs.h b/arch/arm/mach-versatile/include/mach/irqs.h
index bf44c61..fcd2a95 100644
--- a/arch/arm/mach-versatile/include/mach/irqs.h
+++ b/arch/arm/mach-versatile/include/mach/irqs.h
@@ -26,6 +26,7 @@
* held within platform.h
*/
#define IRQ_VIC_START 0
+#define FIQ_START IRQ_VIC_START
#define IRQ_WDOGINT (IRQ_VIC_START + INT_WDOGINT)
#define IRQ_SOFTINT (IRQ_VIC_START + INT_SOFTINT)
#define IRQ_COMMRx (IRQ_VIC_START + INT_COMMRx)
diff --git a/arch/arm/mach-versatile/kgdb_fiq.c b/arch/arm/mach-versatile/kgdb_fiq.c
new file mode 100644
index 0000000..3cdf71d
--- /dev/null
+++ b/arch/arm/mach-versatile/kgdb_fiq.c
@@ -0,0 +1,31 @@
+/*
+ * KGDB FIQ board support
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/kgdb.h>
+#include <mach/hardware.h>
+#include <mach/platform.h>
+#include <asm/hardware/vic.h>
+
+static int kgdb_fiq;
+module_param_named(uart_num, kgdb_fiq, int, 0600);
+MODULE_PARM_DESC(uart_num, "UART<number> port to use for KGDB FIQ");
+
+static int __init kgdb_fiq_init(void)
+{
+ WARN_ON(kgdb_fiq > INT_UARTINT2 - INT_UARTINT0);
+
+ return kgdb_register_fiq(INT_UARTINT0 + kgdb_fiq,
+ vic_fiq_select,
+ vic_is_fiq_rised);
+}
+console_initcall(kgdb_fiq_init);
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread* [PATCH 8/8] ARM: Get rid of .LCcralign local label usage in alignment_trap macro
2012-07-13 10:16 [PATCH v2 0/8] KGDB/KDB FIQ (NMI) debugger Anton Vorontsov
` (6 preceding siblings ...)
2012-07-13 10:16 ` [PATCH 7/8] ARM: versatile: Make able to use UART ports for KGDB FIQ debugger Anton Vorontsov
@ 2012-07-13 10:16 ` Anton Vorontsov
7 siblings, 0 replies; 9+ messages in thread
From: Anton Vorontsov @ 2012-07-13 10:16 UTC (permalink / raw)
To: Russell King, Jason Wessel
Cc: Arve Hjønnevåg, Colin Cross, John Stultz, linux-kernel,
linux-arm-kernel, linaro-kernel, patches, kernel-team,
kgdb-bugreport
This makes the code more izolated.
The downside of this is that we now have an additional branch and the
code itself is 8 bytes longer. But on the bright side, this new layout
can be more cache friendly since cr_alignment address might be already
in the cache line (not that I measured anything, it's just fun to think
about it).
Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
---
arch/arm/kernel/entry-armv.S | 2 --
| 6 +++++-
arch/arm/kernel/kgdb_fiq_entry.S | 3 ---
3 files changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index 6aeb9b8..6b04ab5 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -266,8 +266,6 @@ __pabt_svc:
ENDPROC(__pabt_svc)
.align 5
-.LCcralign:
- .word cr_alignment
#ifdef MULTI_DABORT
.LCprocfns:
.word processor
--git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index c3c09ac..5a05e7f 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -38,9 +38,13 @@
.macro alignment_trap, rtemp
#ifdef CONFIG_ALIGNMENT_TRAP
- ldr \rtemp, .LCcralign
+ ldr \rtemp, 1f
ldr \rtemp, [\rtemp]
mcr p15, 0, \rtemp, c1, c0
+ b 2f
+1:
+ .word cr_alignment
+2:
#endif
.endm
diff --git a/arch/arm/kernel/kgdb_fiq_entry.S b/arch/arm/kernel/kgdb_fiq_entry.S
index 7be3726..e7c05fc 100644
--- a/arch/arm/kernel/kgdb_fiq_entry.S
+++ b/arch/arm/kernel/kgdb_fiq_entry.S
@@ -18,9 +18,6 @@
.text
-@ This is needed for usr_entry/alignment_trap
-.LCcralign:
- .long cr_alignment
.LCdohandle:
.long kgdb_fiq_do_handle
--
1.7.10.4
^ permalink raw reply related [flat|nested] 9+ messages in thread