summaryrefslogtreecommitdiffstats
path: root/arch/Kconfig
diff options
context:
space:
mode:
authorMichael Neuling <mikey@neuling.org>2013-08-09 17:29:29 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-08-09 18:07:05 +1000
commit2517617e0de65f8f7cfe75cae745d06b1fa98586 (patch)
treee0350aa1f8260dc0b25ab7adf3b83d7ab0b46060 /arch/Kconfig
parent74e400cee6c0266ba2d940ed78d981f1e24a8167 (diff)
powerpc: Fix context switch DSCR on POWER8
POWER8 allows the DSCR to be accessed directly from userspace via a new SPR number 0x3 (Rather than 0x11. DSCR SPR number 0x11 is still used on POWER8 but like POWER7, is only accessible in HV and OS modes). Currently, we allow this by setting H/FSCR DSCR bit on boot. Unfortunately this doesn't work, as the kernel needs to see the DSCR change so that it knows to no longer restore the system wide version of DSCR on context switch (ie. to set thread.dscr_inherit). This clears the H/FSCR DSCR bit initially. If a process then accesses the DSCR (via SPR 0x3), it'll trap into the kernel where we set thread.dscr_inherit in facility_unavailable_exception(). We also change _switch() so that we set or clear the H/FSCR DSCR bit based on the thread.dscr_inherit. Signed-off-by: Michael Neuling <mikey@neuling.org> Cc: <stable@vger.kernel.org> [v3.10] Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/Kconfig')
0 files changed, 0 insertions, 0 deletions