diff options
| author | Madhavan Srinivasan <maddy@linux.vnet.ibm.com> | 2013-10-02 00:34:10 +0530 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-07-09 10:51:22 -0700 |
| commit | 08ccce4afe13b2dcad0ac2a86b7bc138207814ff (patch) | |
| tree | 5e865865d69f862b86425f41e44f0ce187807af9 | |
| parent | badd9b71c5651a687d042966a5fa8d195e9cffe4 (diff) | |
powerpc/sysfs: Disable writing to PURR in guest mode
commit d1211af3049f4c9c1d8d4eb8f8098cc4f4f0d0c7 upstream.
arch/powerpc/kernel/sysfs.c exports PURR with write permission.
This may be valid for kernel in phyp mode. But writing to
the file in guest mode causes crash due to a priviledge violation
Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[Backported to 3.4: adjust context]
Signed-off-by: Yijing Wang <wangyijing@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/powerpc/kernel/sysfs.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c index 8302af64921..a191a72372f 100644 --- a/arch/powerpc/kernel/sysfs.c +++ b/arch/powerpc/kernel/sysfs.c @@ -17,6 +17,7 @@ #include <asm/machdep.h> #include <asm/smp.h> #include <asm/pmc.h> +#include <asm/firmware.h> #include "cacheinfo.h" @@ -179,15 +180,25 @@ SYSFS_PMCSETUP(spurr, SPRN_SPURR); SYSFS_PMCSETUP(dscr, SPRN_DSCR); SYSFS_PMCSETUP(pir, SPRN_PIR); +/* + Lets only enable read for phyp resources and + enable write when needed with a separate function. + Lets be conservative and default to pseries. + */ static DEVICE_ATTR(mmcra, 0600, show_mmcra, store_mmcra); static DEVICE_ATTR(spurr, 0600, show_spurr, NULL); static DEVICE_ATTR(dscr, 0600, show_dscr, store_dscr); -static DEVICE_ATTR(purr, 0600, show_purr, store_purr); +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 void add_write_permission_dev_attr(struct device_attribute *attr) +{ + attr->attr.mode |= 0200; +} + static ssize_t show_dscr_default(struct device *dev, struct device_attribute *attr, char *buf) { @@ -394,8 +405,11 @@ static void __cpuinit register_cpu_online(unsigned int cpu) if (cpu_has_feature(CPU_FTR_MMCRA)) device_create_file(s, &dev_attr_mmcra); - if (cpu_has_feature(CPU_FTR_PURR)) + if (cpu_has_feature(CPU_FTR_PURR)) { + if (!firmware_has_feature(FW_FEATURE_LPAR)) + add_write_permission_dev_attr(&dev_attr_purr); device_create_file(s, &dev_attr_purr); + } if (cpu_has_feature(CPU_FTR_SPURR)) device_create_file(s, &dev_attr_spurr); |