litmus-rt.git - The LITMUS^RT kernel.

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author	Jason Wessel <jason.wessel@windriver.com>	2010-01-28 18:04:43 -0500
committer	Ingo Molnar <mingo@elte.hu>	2010-01-30 02:42:21 -0500
commit	5352ae638e2d7d5c9b2e4d528676bbf2af6fd6f3 (patch)
tree	95bab4d28f7c91bc5b7e79b3e1c879dfe96c52b9 /tools/perf/scripts/python
parent	cc0967490c1c3824bc5b75718b6ca8a51d9f2617 (diff)

perf, hw_breakpoint, kgdb: Do not take mutex for kernel debugger

This patch fixes the regression in functionality where the kernel debugger and the perf API do not nicely share hw breakpoint reservations. The kernel debugger cannot use any mutex_lock() calls because it can start the kernel running from an invalid context. A mutex free version of the reservation API needed to get created for the kernel debugger to safely update hw breakpoint reservations. The possibility for a breakpoint reservation to be concurrently processed at the time that kgdb interrupts the system is improbable. Should this corner case occur the end user is warned, and the kernel debugger will prohibit updating the hardware breakpoint reservations. Any time the kernel debugger reserves a hardware breakpoint it will be a system wide reservation. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: kgdb-bugreport@lists.sourceforge.net Cc: K.Prasad <prasad@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: torvalds@linux-foundation.org LKML-Reference: <1264719883-7285-3-git-send-email-jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Diffstat (limited to 'tools/perf/scripts/python')

0 files changed, 0 insertions, 0 deletions

/* thread_info.h: common low-level thread information accessors * * Copyright (C) 2002 David Howells (dhowells@redhat.com) * - Incorporating suggestions made by Linus Torvalds */ #ifndef _LINUX_THREAD_INFO_H #define _LINUX_THREAD_INFO_H #include <linux/types.h> struct timespec; struct compat_timespec; /* * System call restart block. */ struct restart_block { long (*fn)(struct restart_block *); union { struct { unsigned long arg0, arg1, arg2, arg3; }; /* For futex_wait and futex_wait_requeue_pi */ struct { u32 __user *uaddr; u32 val; u32 flags; u32 bitset; u64 time; u32 __user *uaddr2; } futex; /* For nanosleep */ struct { clockid_t index; struct timespec __user *rmtp; #ifdef CONFIG_COMPAT struct compat_timespec __user *compat_rmtp; #endif u64 expires; } nanosleep; /* For poll */ struct { struct pollfd __user *ufds; int nfds; int has_timeout; unsigned long tv_sec; unsigned long tv_nsec; } poll; }; }; extern long do_no_restart_syscall(struct restart_block *parm); #include <linux/bitops.h> #include <asm/thread_info.h> #ifdef __KERNEL__ /* * flag set/clear/test wrappers * - pass TIF_xxxx constants to these functions */ static inline void set_ti_thread_flag(struct thread_info *ti, int flag) { set_bit(flag, (unsigned long *)&ti->flags); } static inline void clear_ti_thread_flag(struct thread_info *ti, int flag) { clear_bit(flag, (unsigned long *)&ti->flags); } static inline int test_and_set_ti_thread_flag(struct thread_info *ti, int flag) { return test_and_set_bit(flag, (unsigned long *)&ti->flags); } static inline int test_and_clear_ti_thread_flag(struct thread_info *ti, int flag) { return test_and_clear_bit(flag, (unsigned long *)&ti->flags); } static inline int test_ti_thread_flag(struct thread_info *ti, int flag) { return test_bit(flag, (unsigned long *)&ti->flags); } #define set_thread_flag(flag) \ set_ti_thread_flag(current_thread_info(), flag) #define clear_thread_flag(flag) \ clear_ti_thread_flag(current_thread_info(), flag) #define test_and_set_thread_flag(flag) \ test_and_set_ti_thread_flag(current_thread_info(), flag) #define test_and_clear_thread_flag(flag) \ test_and_clear_ti_thread_flag(current_thread_info(), flag) #define test_thread_flag(flag) \ test_ti_thread_flag(current_thread_info(), flag) #define set_need_resched() set_thread_flag(TIF_NEED_RESCHED) #define clear_need_resched() clear_thread_flag(TIF_NEED_RESCHED) #if defined TIF_RESTORE_SIGMASK && !defined HAVE_SET_RESTORE_SIGMASK /* * An arch can define its own version of set_restore_sigmask() to get the * job done however works, with or without TIF_RESTORE_SIGMASK. */ #define HAVE_SET_RESTORE_SIGMASK 1 /** * set_restore_sigmask() - make sure saved_sigmask processing gets done * * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code * will run before returning to user mode, to process the flag. For * all callers, TIF_SIGPENDING is already set or it's no harm to set * it. TIF_RESTORE_SIGMASK need not be in the set of bits that the * arch code will notice on return to user mode, in case those bits * are scarce. We set TIF_SIGPENDING here to ensure that the arch * signal code always gets run when TIF_RESTORE_SIGMASK is set. */ static inline void set_restore_sigmask(void) { set_thread_flag(TIF_RESTORE_SIGMASK); set_thread_flag(TIF_SIGPENDING); } #endif /* TIF_RESTORE_SIGMASK && !HAVE_SET_RESTORE_SIGMASK */ #endif /* __KERNEL__ */ #endif /* _LINUX_THREAD_INFO_H */


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