path: root/arch/powerpc/oprofile/op_model_pa6t.c
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authorPaul Mackerras <paulus@samba.org>2011-05-01 19:48:20 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2011-05-04 15:22:09 +1000
commit48404f2e95ef0ffd8134d89c8abcd1a15e15f1b0 (patch)
treec1f55c2b59f4c32848152a4bdc23aac8537b8cbb /arch/powerpc/oprofile/op_model_pa6t.c
parent1977b502120d44b9b4897703adfb2e2fab346880 (diff)
powerpc: Save Come-From Address Register (CFAR) in exception frame
Recent 64-bit server processors (POWER6 and POWER7) have a "Come-From Address Register" (CFAR), that records the address of the most recent branch or rfid (return from interrupt) instruction for debugging purposes. This saves the value of the CFAR in the exception entry code and stores it in the exception frame. We also make xmon print the CFAR value in its register dump code. Rather than extend the pt_regs struct at this time, we steal the orig_gpr3 field, which is only used for system calls, and use it for the CFAR value for all exceptions/interrupts other than system calls. This means we don't save the CFAR on system calls, which is not a great problem since system calls tend not to happen unexpectedly, and also avoids adding the overhead of reading the CFAR to the system call entry path. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/oprofile/op_model_pa6t.c')
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