// SPDX-License-Identifier: GPL-2.0+
//
// Security related flags and so on.
//
// Copyright 2018, Michael Ellerman, IBM Corporation.
#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/seq_buf.h>
#include <asm/asm-prototypes.h>
#include <asm/code-patching.h>
#include <asm/debugfs.h>
#include <asm/security_features.h>
#include <asm/setup.h>
unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
enum count_cache_flush_type {
COUNT_CACHE_FLUSH_NONE = 0x1,
COUNT_CACHE_FLUSH_SW = 0x2,
COUNT_CACHE_FLUSH_HW = 0x4,
};
static enum count_cache_flush_type count_cache_flush_type = COUNT_CACHE_FLUSH_NONE;
bool barrier_nospec_enabled;
static bool no_nospec;
static bool btb_flush_enabled;
#if defined([31mCONFIG_PPC_FSL_BOOK3E[0m) || defined([31mCONFIG_PPC_BOOK3S_64[0m)
static bool no_spectrev2;
#endif
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);
if (!no_nospec && !cpu_mitigations_off())
enable_barrier_nospec(enable);
}
static int __init handle_nospectre_v1(char *p)
{
no_nospec = true;
return 0;
}
early_param("nospectre_v1", handle_nospectre_v1);
#ifdef [31mCONFIG_DEBUG_FS[0m
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);
static __init int security_feature_debugfs_init(void)
{
debugfs_create_x64("security_features", 0400, powerpc_debugfs_root,
(u64 *)&powerpc_security_features);
return 0;
}
device_initcall(security_feature_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
#if defined([31mCONFIG_PPC_FSL_BOOK3E[0m) || defined([31mCONFIG_PPC_BOOK3S_64[0m)
static int __init handle_nospectre_v2(char *p)
{
no_spectrev2 = true;
return 0;
}
early_param("nospectre_v2", handle_nospectre_v2);
#endif /* CONFIG_PPC_FSL_BOOK3E || CONFIG_PPC_BOOK3S_64 */
#ifdef [31mCONFIG_PPC_FSL_BOOK3E[0m
void setup_spectre_v2(void)
{
if (no_spectrev2 || cpu_mitigations_off())
do_btb_flush_fixups();
else
btb_flush_enabled = true;
}
#endif /* CONFIG_PPC_FSL_BOOK3E */
#ifdef [31mCONFIG_PPC_BOOK3S_64[0m
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");
}
#endif
ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
{
struct seq_buf s;
seq_buf_init(&s, buf, PAGE_SIZE - 1);
if (security_ftr_enabled(SEC_FTR_BNDS_CHK_SPEC_BAR)) {
if (barrier_nospec_enabled)
seq_buf_printf(&s, "Mitigation: __user pointer sanitization");
else
seq_buf_printf(&s, "Vulnerable");
if (security_ftr_enabled(SEC_FTR_SPEC_BAR_ORI31))
seq_buf_printf(&s, ", ori31 speculation barrier enabled");
seq_buf_printf(&s, "\n");
} else
seq_buf_printf(&s, "Not affected\n");
return s.len;
}
ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
{
struct seq_buf s;
bool bcs, ccd;
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);
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 if (count_cache_flush_type != COUNT_CACHE_FLUSH_NONE) {
seq_buf_printf(&s, "Mitigation: Software count cache flush");
if (count_cache_flush_type == COUNT_CACHE_FLUSH_HW)
seq_buf_printf(&s, " (hardware accelerated)");
} else if (btb_flush_enabled) {
seq_buf_printf(&s, "Mitigation: Branch predictor state flush");
} else {
seq_buf_printf(&s, "Vulnerable");
}
seq_buf_printf(&s, "\n");
return s.len;
}
#ifdef [31mCONFIG_PPC_BOOK3S_64[0m
/*
* Store-forwarding barrier support.
*/
static enum stf_barrier_type stf_enabled_flush_types;
static bool no_stf_barrier;
bool stf_barrier;
static int __init handle_no_stf_barrier(char *p)
{
pr_info("stf-barrier: disabled on command line.");
no_stf_barrier = true;
return 0;
}
early_param("no_stf_barrier", handle_no_stf_barrier);
/* This is the generic flag used by other architectures */
static int __init handle_ssbd(char *p)
{
if (!p || strncmp(p, "auto", 5) == 0 || strncmp(p, "on", 2) == 0 ) {
/* Until firmware tells us, we have the barrier with auto */
return 0;
} else if (strncmp(p, "off", 3) == 0) {
handle_no_stf_barrier(NULL);
return 0;
} else
return 1;
return 0;
}
early_param("spec_store_bypass_disable", handle_ssbd);
/* This is the generic flag used by other architectures */
static int __init handle_no_ssbd(char *p)
{
handle_no_stf_barrier(NULL);
return 0;
}
early_param("nospec_store_bypass_disable", handle_no_ssbd);
static void stf_barrier_enable(bool enable)
{
if (enable)
do_stf_barrier_fixups(stf_enabled_flush_types);
else
do_stf_barrier_fixups(STF_BARRIER_NONE);
stf_barrier = enable;
}
void setup_stf_barrier(void)
{
enum stf_barrier_type type;
bool enable, hv;
hv = cpu_has_feature(CPU_FTR_HVMODE);
/* Default to fallback in case fw-features are not available */
if (cpu_has_feature(CPU_FTR_ARCH_300))
type = STF_BARRIER_EIEIO;
else if (cpu_has_feature(CPU_FTR_ARCH_207S))
type = STF_BARRIER_SYNC_ORI;
else if (cpu_has_feature(CPU_FTR_ARCH_206))
type = STF_BARRIER_FALLBACK;
else
type = STF_BARRIER_NONE;
enable = security_ftr_enabled(SEC_FTR_FAVOUR_SECURITY) &&
(security_ftr_enabled(SEC_FTR_L1D_FLUSH_PR) ||
(security_ftr_enabled(SEC_FTR_L1D_FLUSH_HV) && hv));
if (type == STF_BARRIER_FALLBACK) {
pr_info("stf-barrier: fallback barrier available\n");
} else if (type == STF_BARRIER_SYNC_ORI) {
pr_info("stf-barrier: hwsync barrier available\n");
} else if (type == STF_BARRIER_EIEIO) {
pr_info("stf-barrier: eieio barrier available\n");
}
stf_enabled_flush_types = type;
if (!no_stf_barrier && !cpu_mitigations_off())
stf_barrier_enable(enable);
}
ssize_t cpu_show_spec_store_bypass(struct device *dev, struct device_attribute *attr, char *buf)
{
if (stf_barrier && stf_enabled_flush_types != STF_BARRIER_NONE) {
const char *type;
switch (stf_enabled_flush_types) {
case STF_BARRIER_EIEIO:
type = "eieio";
break;
case STF_BARRIER_SYNC_ORI:
type = "hwsync";
break;
case STF_BARRIER_FALLBACK:
type = "fallback";
break;
default:
type = "unknown";
}
return sprintf(buf, "Mitigation: Kernel entry/exit barrier (%s)\n", type);
}
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");
}
#ifdef [31mCONFIG_DEBUG_FS[0m
static int stf_barrier_set(void *data, u64 val)
{
bool enable;
if (val == 1)
enable = true;
else if (val == 0)
enable = false;
else
return -EINVAL;
/* Only do anything if we're changing state */
if (enable != stf_barrier)
stf_barrier_enable(enable);
return 0;
}
static int stf_barrier_get(void *data, u64 *val)
{
*val = stf_barrier ? 1 : 0;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_stf_barrier, stf_barrier_get, stf_barrier_set, "%llu\n");
static __init int stf_barrier_debugfs_init(void)
{
debugfs_create_file("stf_barrier", 0600, powerpc_debugfs_root, NULL, &fops_stf_barrier);
return 0;
}
device_initcall(stf_barrier_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
static void toggle_count_cache_flush(bool enable)
{
if (!enable || !security_ftr_enabled(SEC_FTR_FLUSH_COUNT_CACHE)) {
patch_instruction_site(&patch__call_flush_count_cache, PPC_INST_NOP);
count_cache_flush_type = COUNT_CACHE_FLUSH_NONE;
pr_info("count-cache-flush: software flush disabled.\n");
return;
}
patch_branch_site(&patch__call_flush_count_cache,
(u64)&flush_count_cache, BRANCH_SET_LINK);
if (!security_ftr_enabled(SEC_FTR_BCCTR_FLUSH_ASSIST)) {
count_cache_flush_type = COUNT_CACHE_FLUSH_SW;
pr_info("count-cache-flush: full software flush sequence enabled.\n");
return;
}
patch_instruction_site(&patch__flush_count_cache_return, PPC_INST_BLR);
count_cache_flush_type = COUNT_CACHE_FLUSH_HW;
pr_info("count-cache-flush: hardware assisted flush sequence enabled\n");
}
void setup_count_cache_flush(void)
{
bool enable = true;
if (no_spectrev2 || cpu_mitigations_off()) {
if (security_ftr_enabled(SEC_FTR_BCCTRL_SERIALISED) ||
security_ftr_enabled(SEC_FTR_COUNT_CACHE_DISABLED))
pr_warn("Spectre v2 mitigations not under software control, can't disable\n");
enable = false;
}
toggle_count_cache_flush(enable);
}
#ifdef [31mCONFIG_DEBUG_FS[0m
static int count_cache_flush_set(void *data, u64 val)
{
bool enable;
if (val == 1)
enable = true;
else if (val == 0)
enable = false;
else
return -EINVAL;
toggle_count_cache_flush(enable);
return 0;
}
static int count_cache_flush_get(void *data, u64 *val)
{
if (count_cache_flush_type == COUNT_CACHE_FLUSH_NONE)
*val = 0;
else
*val = 1;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_count_cache_flush, count_cache_flush_get,
count_cache_flush_set, "%llu\n");
static __init int count_cache_flush_debugfs_init(void)
{
debugfs_create_file("count_cache_flush", 0600, powerpc_debugfs_root,
NULL, &fops_count_cache_flush);
return 0;
}
device_initcall(count_cache_flush_debugfs_init);
#endif /* CONFIG_DEBUG_FS */
#endif /* CONFIG_PPC_BOOK3S_64 */