[PATCH][v2] powerpc: Set right value of Speculation_Store_Bypass in /proc/<pid>/status

From: Gustavo Walbon
Date: Sat Nov 23 2019 - 18:09:11 EST


The issue has showed the value of status of Speculation_Store_Bypass in the
/proc/<pid>/status as `unknown` for PowerPC systems.

The patch fix the checking of the mitigation status of Speculation, and
can be reported as "not vulnerable", "globally mitigated" or "vulnerable".

Link: https://github.com/linuxppc/issues/issues/255

Changelog:
Rebase on v5.4-rc8

Signed-off-by: Gustavo Walbon <gwalbon@xxxxxxxxxxxxx>
---
arch/powerpc/kernel/security.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 7d4b2080a658..04e566026bbc 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -14,7 +14,7 @@
#include <asm/debugfs.h>
#include <asm/security_features.h>
#include <asm/setup.h>
-
+#include <linux/prctl.h>

u64 powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;

@@ -344,6 +344,29 @@ ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *
return sprintf(buf, "Vulnerable\n");
}

+static int ssb_prctl_get(struct task_struct *task)
+{
+ if (stf_barrier) {
+ if (stf_enabled_flush_types == STF_BARRIER_NONE)
+ return PR_SPEC_NOT_AFFECTED;
+ else
+ return PR_SPEC_DISABLE;
+ } else
+ return PR_SPEC_DISABLE_NOEXEC;
+
+ return -EINVAL;
+}
+
+int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which)
+{
+ switch (which) {
+ case PR_SPEC_STORE_BYPASS:
+ return ssb_prctl_get(task);
+ default:
+ return -ENODEV;
+ }
+}
+
#ifdef CONFIG_DEBUG_FS
static int stf_barrier_set(void *data, u64 val)
{
--
2.19.1