Author: jhb Date: Fri Nov 5 13:42:58 2010 New Revision: 214835 URL: http://svn.freebsd.org/changeset/base/214835
Log: Adjust the order of operations in spinlock_enter() and spinlock_exit() to work properly with single-stepping in a kernel debugger. Specifically, these routines have always disabled interrupts before increasing the nesting count and restored the prior state of interrupts after decreasing the nesting count to avoid problems with a nested interrupt not disabling interrupts when acquiring a spin lock. However, trap interrupts for single-stepping can still occur even when interrupts are disabled. Now the saved state of interrupts is not saved in the thread until after interrupts have been disabled and the nesting count has been increased. Similarly, the saved state from the thread cannot be read once the nesting count has been decreased to zero. To fix this, use temporary variables to store interrupt state and shuffle it between the thread's MD area and the appropriate registers. In cooperation with: bde MFC after: 1 month Modified: head/sys/amd64/amd64/machdep.c head/sys/arm/arm/machdep.c head/sys/i386/i386/machdep.c head/sys/ia64/ia64/machdep.c head/sys/mips/mips/machdep.c head/sys/pc98/pc98/machdep.c head/sys/powerpc/aim/machdep.c head/sys/powerpc/booke/machdep.c head/sys/sparc64/sparc64/machdep.c head/sys/sun4v/sun4v/machdep.c Modified: head/sys/amd64/amd64/machdep.c ============================================================================== --- head/sys/amd64/amd64/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/amd64/amd64/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -1762,11 +1762,15 @@ void spinlock_enter(void) { struct thread *td; + register_t flags; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_flags = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + flags = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_flags = flags; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -1774,12 +1778,14 @@ void spinlock_exit(void) { struct thread *td; + register_t flags; td = curthread; critical_exit(); + flags = td->td_md.md_saved_flags; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_flags); + intr_restore(flags); } /* Modified: head/sys/arm/arm/machdep.c ============================================================================== --- head/sys/arm/arm/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/arm/arm/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -493,11 +493,15 @@ void spinlock_enter(void) { struct thread *td; + register_t cspr; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_cspr = disable_interrupts(I32_bit | F32_bit); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + cspr = disable_interrupts(I32_bit | F32_bit); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_cspr = cspr; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -505,12 +509,14 @@ void spinlock_exit(void) { struct thread *td; + register_t cspr; td = curthread; critical_exit(); + cspr = td->td_md.md_saved_cspr; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - restore_interrupts(td->td_md.md_saved_cspr); + restore_interrupts(cspr); } /* Modified: head/sys/i386/i386/machdep.c ============================================================================== --- head/sys/i386/i386/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/i386/i386/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -2997,11 +2997,15 @@ void spinlock_enter(void) { struct thread *td; + register_t flags; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_flags = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + flags = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_flags = flags; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -3009,12 +3013,14 @@ void spinlock_exit(void) { struct thread *td; + register_t flags; td = curthread; critical_exit(); + flags = td->td_md.md_saved_flags; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_flags); + intr_restore(flags); } #if defined(I586_CPU) && !defined(NO_F00F_HACK) Modified: head/sys/ia64/ia64/machdep.c ============================================================================== --- head/sys/ia64/ia64/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/ia64/ia64/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -513,11 +513,15 @@ void spinlock_enter(void) { struct thread *td; + int intr; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_intr = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + intr = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_intr = intr; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -525,12 +529,14 @@ void spinlock_exit(void) { struct thread *td; + int intr; td = curthread; critical_exit(); + intr = td->td_md.md_saved_intr; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_intr); + intr_restore(intr); } void Modified: head/sys/mips/mips/machdep.c ============================================================================== --- head/sys/mips/mips/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/mips/mips/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -450,11 +450,15 @@ void spinlock_enter(void) { struct thread *td; + register_t intr; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_intr = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + intr = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_intr = intr; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -462,12 +466,14 @@ void spinlock_exit(void) { struct thread *td; + register_t intr; td = curthread; critical_exit(); + intr = td->td_md.md_saved_intr; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_intr); + intr_restore(intr); } /* Modified: head/sys/pc98/pc98/machdep.c ============================================================================== --- head/sys/pc98/pc98/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/pc98/pc98/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -2340,11 +2340,15 @@ void spinlock_enter(void) { struct thread *td; + register_t flags; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_flags = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + flags = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_flags = flags; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -2352,12 +2356,14 @@ void spinlock_exit(void) { struct thread *td; + register_t flags; td = curthread; critical_exit(); + flags = td->td_md.md_saved_flags; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_flags); + intr_restore(flags); } #if defined(I586_CPU) && !defined(NO_F00F_HACK) Modified: head/sys/powerpc/aim/machdep.c ============================================================================== --- head/sys/powerpc/aim/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/powerpc/aim/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -751,11 +751,15 @@ void spinlock_enter(void) { struct thread *td; + register_t msr; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_msr = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + msr = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_msr = msr; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -763,12 +767,14 @@ void spinlock_exit(void) { struct thread *td; + register_t msr; td = curthread; critical_exit(); + msr = td->td_md.md_saved_msr; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_msr); + intr_restore(msr); } /* Modified: head/sys/powerpc/booke/machdep.c ============================================================================== --- head/sys/powerpc/booke/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/powerpc/booke/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -516,11 +516,15 @@ void spinlock_enter(void) { struct thread *td; + register_t msr; td = curthread; - if (td->td_md.md_spinlock_count == 0) - td->td_md.md_saved_msr = intr_disable(); - td->td_md.md_spinlock_count++; + if (td->td_md.md_spinlock_count == 0) { + msr = intr_disable(); + td->td_md.md_spinlock_count = 1; + td->td_md.md_saved_msr = msr; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -528,12 +532,14 @@ void spinlock_exit(void) { struct thread *td; + register_t msr; td = curthread; critical_exit(); + msr = td->td_md.md_saved_msr; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - intr_restore(td->td_md.md_saved_msr); + intr_restore(msr); } /* Shutdown the CPU as much as possible. */ Modified: head/sys/sparc64/sparc64/machdep.c ============================================================================== --- head/sys/sparc64/sparc64/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/sparc64/sparc64/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -224,9 +224,10 @@ spinlock_enter(void) if (td->td_md.md_spinlock_count == 0) { pil = rdpr(pil); wrpr(pil, 0, PIL_TICK); + td->td_md.md_spinlock_count = 1; td->td_md.md_saved_pil = pil; - } - td->td_md.md_spinlock_count++; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -234,12 +235,14 @@ void spinlock_exit(void) { struct thread *td; + register_t pil; td = curthread; critical_exit(); + pil = td->td_md.md_saved_pil; td->td_md.md_spinlock_count--; if (td->td_md.md_spinlock_count == 0) - wrpr(pil, td->td_md.md_saved_pil, 0); + wrpr(pil, pil, 0); } static phandle_t Modified: head/sys/sun4v/sun4v/machdep.c ============================================================================== --- head/sys/sun4v/sun4v/machdep.c Fri Nov 5 11:31:39 2010 (r214834) +++ head/sys/sun4v/sun4v/machdep.c Fri Nov 5 13:42:58 2010 (r214835) @@ -269,9 +269,10 @@ spinlock_enter(void) td = curthread; if (td->td_md.md_spinlock_count == 0) { pil = intr_disable(); + td->td_md.md_spinlock_count = 1; td->td_md.md_saved_pil = pil; - } - td->td_md.md_spinlock_count++; + } else + td->td_md.md_spinlock_count++; critical_enter(); } @@ -279,14 +280,14 @@ void spinlock_exit(void) { struct thread *td; + register_t pil; td = curthread; critical_exit(); + pil = td->td_md.md_saved_pil; td->td_md.md_spinlock_count--; - if (td->td_md.md_spinlock_count == 0) { - intr_restore(td->td_md.md_saved_pil); - } - + if (td->td_md.md_spinlock_count == 0) + intr_restore(pil); } unsigned _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"