diff options
| author | Anton Blanchard <anton@samba.org> | 2012-09-03 16:48:46 +0000 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2012-09-19 15:04:41 +0100 |
| commit | 5f31a641ff0e76081cf4ae1f72799cd59c20baea (patch) | |
| tree | 15924f534cdd7048822cb1e798642b656bd37846 /arch | |
| parent | b32fef3b4df0e254fb4d0fd3122a2668a5f11581 (diff) | |
powerpc: Keep thread.dscr and thread.dscr_inherit in sync
commit 00ca0de02f80924dfff6b4f630e1dff3db005e35 upstream.
When we update the DSCR either via emulation of mtspr(DSCR) or via
a change to dscr_default in sysfs we don't update thread.dscr.
We will eventually update it at context switch time but there is
a period where thread.dscr is incorrect.
If we fork at this point we will copy the old value of thread.dscr
into the child. To avoid this, always keep thread.dscr in sync with
reality.
This issue was found with the following testcase:
http://ozlabs.org/~anton/junkcode/dscr_inherit_test.c
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/sysfs.c | 4 | ||||
| -rw-r--r-- | arch/powerpc/kernel/traps.c | 3 |
2 files changed, 5 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 0c3f94919574..55be64db0ae0 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -194,8 +194,10 @@ static ssize_t show_dscr_default(struct sysdev_class *class, static void update_dscr(void *dummy) { - if (!current->thread.dscr_inherit) + if (!current->thread.dscr_inherit) { + current->thread.dscr = dscr_default; mtspr(SPRN_DSCR, dscr_default); + } } static ssize_t __used store_dscr_default(struct sysdev_class *class, diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 5459d148a0f6..82dcd4d8b4eb 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -942,8 +942,9 @@ static int emulate_instruction(struct pt_regs *regs) cpu_has_feature(CPU_FTR_DSCR)) { PPC_WARN_EMULATED(mtdscr, regs); rd = (instword >> 21) & 0x1f; - mtspr(SPRN_DSCR, regs->gpr[rd]); + current->thread.dscr = regs->gpr[rd]; current->thread.dscr_inherit = 1; + mtspr(SPRN_DSCR, current->thread.dscr); return 0; } #endif |