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authorSam bobroff <sam.bobroff@au1.ibm.com>2014-05-21 16:32:38 +1000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2014-05-28 13:35:40 +1000
commit1739ea9e13e636590dd56c2f4ca85e783da512e7 (patch)
treefcdebf258849e18544f05cdabcf176837c0b3778 /arch/powerpc/kernel/sysfs.c
parent39a360ef7234942333436709fd6cf641d5c51b7b (diff)
downloadlinux-1739ea9e13e636590dd56c2f4ca85e783da512e7.tar.bz2
powerpc: Fix regression of per-CPU DSCR setting
Since commit "efcac65 powerpc: Per process DSCR + some fixes (try#4)" it is no longer possible to set the DSCR on a per-CPU basis. The old behaviour was to minipulate the DSCR SPR directly but this is no longer sufficient: the value is quickly overwritten by context switching. This patch stores the per-CPU DSCR value in a kernel variable rather than directly in the SPR and it is used whenever a process has not set the DSCR itself. The sysfs interface (/sys/devices/system/cpu/cpuN/dscr) is unchanged. Writes to the old global default (/sys/devices/system/cpu/dscr_default) now set all of the per-CPU values and reads return the last written value. The new per-CPU default is added to the paca_struct and is used everywhere outside of sysfs.c instead of the old global default. Signed-off-by: Sam Bobroff <sam.bobroff@au1.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/sysfs.c')
-rw-r--r--arch/powerpc/kernel/sysfs.c32
1 files changed, 19 insertions, 13 deletions
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index e2a1d6fb3297..67fd2fd2620a 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -484,7 +484,6 @@ SYSFS_PMCSETUP(pmc8, SPRN_PMC8);
SYSFS_PMCSETUP(mmcra, SPRN_MMCRA);
SYSFS_SPRSETUP(purr, SPRN_PURR);
SYSFS_SPRSETUP(spurr, SPRN_SPURR);
-SYSFS_SPRSETUP(dscr, SPRN_DSCR);
SYSFS_SPRSETUP(pir, SPRN_PIR);
/*
@@ -494,12 +493,27 @@ SYSFS_SPRSETUP(pir, SPRN_PIR);
*/
static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra);
static DEVICE_ATTR(spurr, 0400, show_spurr, NULL);
-static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr);
static DEVICE_ATTR(purr, 0400, show_purr, store_purr);
static DEVICE_ATTR(pir, 0400, show_pir, NULL);
-unsigned long dscr_default = 0;
-EXPORT_SYMBOL(dscr_default);
+static unsigned long dscr_default;
+
+static void read_dscr(void *val)
+{
+ *(unsigned long *)val = get_paca()->dscr_default;
+}
+
+static void write_dscr(void *val)
+{
+ get_paca()->dscr_default = *(unsigned long *)val;
+ if (!current->thread.dscr_inherit) {
+ current->thread.dscr = *(unsigned long *)val;
+ mtspr(SPRN_DSCR, *(unsigned long *)val);
+ }
+}
+
+SYSFS_SPRSETUP_SHOW_STORE(dscr);
+static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr);
static void add_write_permission_dev_attr(struct device_attribute *attr)
{
@@ -512,14 +526,6 @@ static ssize_t show_dscr_default(struct device *dev,
return sprintf(buf, "%lx\n", dscr_default);
}
-static void update_dscr(void *dummy)
-{
- if (!current->thread.dscr_inherit) {
- current->thread.dscr = dscr_default;
- mtspr(SPRN_DSCR, dscr_default);
- }
-}
-
static ssize_t __used store_dscr_default(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
@@ -532,7 +538,7 @@ static ssize_t __used store_dscr_default(struct device *dev,
return -EINVAL;
dscr_default = val;
- on_each_cpu(update_dscr, NULL, 1);
+ on_each_cpu(write_dscr, &val, 1);
return count;
}