[098/117] sparc64: Fix hardirq tracing in trap return path.
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From: Greg KH on 10 May 2010 19:30 2.6.33-stable review patch. If anyone has any objections, please let us know. ------------------ From: David S. Miller <davem(a)davemloft.net> [ Upstream commit 28a1f533ae8606020238b840b82ae70a3f87609e ] We can overflow the hardirq stack if we set the %pil here so early, just let the normal control flow do it. This is fine as we are allowed to do the actual IRQ enable at any point after we call trace_hardirqs_on. Signed-off-by: David S. Miller <davem(a)davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh(a)suse.de> --- arch/sparc/kernel/rtrap_64.S | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) --- a/arch/sparc/kernel/rtrap_64.S +++ b/arch/sparc/kernel/rtrap_64.S @@ -172,7 +172,17 @@ rtrap_xcall: nop call trace_hardirqs_on nop - wrpr %l4, %pil + /* Do not actually set the %pil here. We will do that + * below after we clear PSTATE_IE in the %pstate register. + * If we re-enable interrupts here, we can recurse down + * the hardirq stack potentially endlessly, causing a + * stack overflow. + * + * It is tempting to put this test and trace_hardirqs_on + * call at the 'rt_continue' label, but that will not work + * as that path hits unconditionally and we do not want to + * execute this in NMI return paths, for example. + */ #endif rtrap_no_irq_enable: andcc %l1, TSTATE_PRIV, %l3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |