From: Chris Torek <chris.torek@xxxxxxxxxxxxx> Date: Sat, 14 Mar 2009 16:24:41 -0600 > >"rd %pc, X" doesn't schedule very well at all, it flushes the pipeline > >completely and cannot issue alongside other instructions. > > Oh, in that case maybe the other code that does the "rd %pc" version > should be switched to using sethi/or sequences. (Or maybe it is > already in places where there is no good scheduling.) In many places where we use rd %pc, X we are doing so because we are limited by the number of instructions. For example, in trap table entries. > >It's so easy to reschedule this kgdb capture thing into a software > >interrupt, please code that up and give it a whirl. > > > >Or, as usual, I'll do it :-/ > > Heh. In my case, I will have to go work out how the software > interrupts work, so as to make sure I don't step on some other > interrupt. > > I'll probably get a chance to try sometime Monday or Tuesday though -- > actually I'm working with other folks and they'd be doing the "try" > part -- as I have a pile of other work I have to get done this > weekend and Monday. It's a 2 minute hack, just test this patch below. BTW, there are things which we know won't work with KGDB on platforms like sparc that do single-step in software. SMP KGDB usage on such platforms is basically hit-or-miss because it's very racy. See: http://kerneltrap.org/mailarchive/linux-kernel/2008/4/29/1647204 Just FYI. diff --git a/arch/sparc/include/asm/pil.h b/arch/sparc/include/asm/pil.h index 32a7efe..2669370 100644 --- a/arch/sparc/include/asm/pil.h +++ b/arch/sparc/include/asm/pil.h @@ -24,6 +24,7 @@ #define PIL_DEVICE_IRQ 5 #define PIL_SMP_CALL_FUNC_SNGL 6 #define PIL_DEFERRED_PCR_WORK 7 +#define PIL_KGDB_CAPTURE 8 #define PIL_NORMAL_MAX 14 #define PIL_NMI 15 diff --git a/arch/sparc/kernel/kgdb_64.c b/arch/sparc/kernel/kgdb_64.c index fefbe6d..f5a0fd4 100644 --- a/arch/sparc/kernel/kgdb_64.c +++ b/arch/sparc/kernel/kgdb_64.c @@ -108,7 +108,7 @@ void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs) } #ifdef CONFIG_SMP -void smp_kgdb_capture_client(struct pt_regs *regs) +void smp_kgdb_capture_client(int irq, struct pt_regs *regs) { unsigned long flags; diff --git a/arch/sparc/kernel/ttable.S b/arch/sparc/kernel/ttable.S index d9bdfb9..76d837f 100644 --- a/arch/sparc/kernel/ttable.S +++ b/arch/sparc/kernel/ttable.S @@ -64,7 +64,12 @@ tl0_irq6: TRAP_IRQ(smp_call_function_single_client, 6) tl0_irq6: BTRAP(0x46) #endif tl0_irq7: TRAP_IRQ(deferred_pcr_work_irq, 7) -tl0_irq8: BTRAP(0x48) BTRAP(0x49) +#ifdef CONFIG_KGDB +tl0_irq8: TRAP_IRQ(smp_kgdb_capture_client, 8) +#else +tl0_irq8: BTRAP(0x48) +#endif +tl0_irq9: BTRAP(0x49) tl0_irq10: BTRAP(0x4a) BTRAP(0x4b) BTRAP(0x4c) BTRAP(0x4d) tl0_irq14: TRAP_IRQ(timer_interrupt, 14) tl0_irq15: TRAP_NMI_IRQ(perfctr_irq, 15) diff --git a/arch/sparc/mm/ultra.S b/arch/sparc/mm/ultra.S index 80c788e..b57a594 100644 --- a/arch/sparc/mm/ultra.S +++ b/arch/sparc/mm/ultra.S @@ -679,28 +679,8 @@ xcall_new_mmu_context_version: #ifdef CONFIG_KGDB .globl xcall_kgdb_capture xcall_kgdb_capture: -661: rdpr %pstate, %g2 - wrpr %g2, PSTATE_IG | PSTATE_AG, %pstate - .section .sun4v_2insn_patch, "ax" - .word 661b - nop - nop - .previous - - rdpr %pil, %g2 - wrpr %g0, PIL_NORMAL_MAX, %pil - sethi %hi(109f), %g7 - ba,pt %xcc, etrap_irq -109: or %g7, %lo(109b), %g7 -#ifdef CONFIG_TRACE_IRQFLAGS - call trace_hardirqs_off - nop -#endif - call smp_kgdb_capture_client - add %sp, PTREGS_OFF, %o0 - /* Has to be a non-v9 branch due to the large distance. */ - ba rtrap_xcall - ldx [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1 + wr %g0, (1 << PIL_KGDB_CAPTURE), %set_softint + retry #endif #endif /* CONFIG_SMP */ -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
