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// SPDX-License-Identifier: GPL-2.0+
//
// Security related flags and so on.
//
// Copyright 2018, Michael Ellerman, IBM Corporation.
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/seq_buf.h>
#include <asm/debugfs.h>
#include <asm/security_features.h>
#include <asm/setup.h>
unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
bool barrier_nospec_enabled;
static void enable_barrier_nospec(bool enable)
{
barrier_nospec_enabled = enable;
do_barrier_nospec_fixups(enable);
}
void setup_barrier_nospec(void)
{
bool enable;
/*
* It would make sense to check SEC_FTR_SPEC_BAR_ORI31 below as well.
* But there's a good reason not to. The two flags we check below are
* both are enabled by default in the kernel, so if the hcall is not
* functional they will be enabled.
* On a system where the host firmware has been updated (so the ori
* functions as a barrier), but on which the hypervisor (KVM/Qemu) has
* not been updated, we would like to enable the barrier. Dropping the
* check for SEC_FTR_SPEC_BAR_ORI31 achieves that. The only downside is
* we potentially enable the barrier on systems where the host firmware
* is not updated, but that's harmless as it's a no-op.
*/
enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR);
enable_barrier_nospec(enable);
}
#ifdef CONFIG_DEBUG_FS
static int barrier_nospec_set(void *data, u64 val)
{
switch (val) {
case 0:
case 1:
break;
default:
return -EINVAL;
}
if (!!val == !!barrier_nospec_enabled)
return 0;
enable_barrier_nospec(!!val);
return 0;
}
static int barrier_nospec_get(void *data, u64 *val)
{
*val = barrier_nospec_enabled ? 1 : 0;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_barrier_nospec,
barrier_nospec_get, barrier_nospec_set, "%llu\n");
static __init int barrier_nospec_debugfs_init(void)
{
debugfs_create_file("barrier_nospec", 0600, powerpc_debugfs_root, NULL,
&fops_barrier_nospec);
return 0;
}
device_initcall(barrier_nospec_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
{
bool thread_priv;
thread_priv = security_ftr_enabled(SEC_FTR_L1D_THREAD_PRIV);
if (rfi_flush || thread_priv) {
struct seq_buf s;
seq_buf_init(&s, buf, PAGE_SIZE - 1);
seq_buf_printf(&s, "Mitigation: ");
if (rfi_flush)
seq_buf_printf(&s, "RFI Flush");
if (rfi_flush && thread_priv)
seq_buf_printf(&s, ", ");
if (thread_priv)
seq_buf_printf(&s, "L1D private per thread");
seq_buf_printf(&s, "\n");
return s.len;
}
if (!security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) &&
!security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR))
return sprintf(buf, "Not affected\n");
return sprintf(buf, "Vulnerable\n");
}
ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
{
if (!security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR))
return sprintf(buf, "Not affected\n");
if (barrier_nospec_enabled)
return sprintf(buf, "Mitigation: __user pointer sanitization\n");
return sprintf(buf, "Vulnerable\n");
}
ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
{
bool bcs, ccd, ori;
struct seq_buf s;
seq_buf_init(&s, buf, PAGE_SIZE - 1);
bcs = security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED);
ccd = security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED);
ori = security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31);
if (bcs || ccd) {
seq_buf_printf(&s, "Mitigation: ");
if (bcs)
seq_buf_printf(&s, "Indirect branch serialisation (kernel only)");
if (bcs && ccd)
seq_buf_printf(&s, ", ");
if (ccd)
seq_buf_printf(&s, "Indirect branch cache disabled");
} else
seq_buf_printf(&s, "Vulnerable");
if (ori)
seq_buf_printf(&s, ", ori31 speculation barrier enabled");
seq_buf_printf(&s, "\n");
return s.len;
}
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