Michael Neuling c1fe190c06 powerpc: Add force enable of DAWR on P9 option ... This adds a flag so that the DAWR can be enabled on P9 via: echo Y > /sys/kernel/debug/powerpc/dawr_enable_dangerous The DAWR was previously force disabled on POWER9 in: 9654153158 powerpc: Disable DAWR in the base POWER9 CPU features Also see Documentation/powerpc/DAWR-POWER9.txt This is a dangerous setting, USE AT YOUR OWN RISK. Some users may not care about a bad user crashing their box (ie. single user/desktop systems) and really want the DAWR. This allows them to force enable DAWR. This flag can also be used to disable DAWR access. Once this is cleared, all DAWR access should be cleared immediately and your machine once again safe from crashing. Userspace may get confused by toggling this. If DAWR is force enabled/disabled between getting the number of breakpoints (via PTRACE_GETHWDBGINFO) and setting the breakpoint, userspace will get an inconsistent view of what's available. Similarly for guests. For the DAWR to be enabled in a KVM guest, the DAWR needs to be force enabled in the host AND the guest. For this reason, this won't work on POWERVM as it doesn't allow the HCALL to work. Writes of 'Y' to the dawr_enable_dangerous file will fail if the hypervisor doesn't support writing the DAWR. To double check the DAWR is working, run this kernel selftest: tools/testing/selftests/powerpc/ptrace/ptrace-hwbreak.c Any errors/failures/skips mean something is wrong. Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>		2019-04-20 22:20:45 +10:00
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bootwrapper.txt
cpu_families.txt	powerpc: Add cpu family documentation	2014-06-05 13:20:01 +10:00
cpu_features.txt
cxl.txt	cxl: Add psl9 specific code	2017-04-13 23:34:31 +10:00
cxlflash.txt	scsi: cxlflash: Support AFU debug	2017-06-26 15:01:12 -04:00
DAWR-POWER9.txt	powerpc: Add force enable of DAWR on P9 option	2019-04-20 22:20:45 +10:00
dscr.txt	Doc: powerpc: Fix typos in Documentation/powerpc	2015-07-10 14:00:51 -06:00
eeh-pci-error-recovery.txt	powerpc/eeh: rename EEH from "extended" to "enhanced" error handling	2016-04-11 20:30:42 +10:00
firmware-assisted-dump.txt	powerpc/fadump: Reservationless firmware assisted dump	2018-12-21 11:32:49 +11:00
hvcs.txt
isa-versions.rst	powerpc: Add some documentation of ISA versions	2018-12-20 22:21:20 +11:00
mpc52xx.txt
pci_iov_resource_on_powernv.txt	powerpc/pci: Add PCI resource alignment documentation	2015-03-31 13:02:38 +11:00
pmu-ebb.txt	powerpc/perf: Core EBB support for 64-bit book3s	2013-07-01 11:50:10 +10:00
ptrace.txt
qe_firmware.txt	Doc: powerpc: Fix typos in Documentation/powerpc	2015-07-10 14:00:51 -06:00
syscall64-abi.txt	powerpc/64: Document the syscall ABI	2016-09-20 14:36:14 +10:00
transactional_memory.txt	powerpc: Document issues with TM on POWER9	2018-07-02 23:54:29 +10:00