@@ -69,6 +69,27 @@
*/
#define EX_R3 EX_DAR
+#define STF_ENTRY_BARRIER_SLOT \
+ STF_ENTRY_BARRIER_FIXUP_SECTION; \
+ nop; \
+ nop; \
+ nop
+
+#define STF_EXIT_BARRIER_SLOT \
+ STF_EXIT_BARRIER_FIXUP_SECTION; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop; \
+ nop
+
+/*
+ * r10 must be free to use, r13 must be paca
+ */
+#define INTERRUPT_TO_KERNEL \
+ STF_ENTRY_BARRIER_SLOT
+
/*
* Macros for annotating the expected destination of (h)rfid
*
@@ -85,16 +106,19 @@
rfid
#define RFI_TO_USER \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
rfid; \
b rfi_flush_fallback
#define RFI_TO_USER_OR_KERNEL \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
rfid; \
b rfi_flush_fallback
#define RFI_TO_GUEST \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
rfid; \
b rfi_flush_fallback
@@ -103,21 +127,25 @@
hrfid
#define HRFI_TO_USER \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
hrfid; \
b hrfi_flush_fallback
#define HRFI_TO_USER_OR_KERNEL \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
hrfid; \
b hrfi_flush_fallback
#define HRFI_TO_GUEST \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
hrfid; \
b hrfi_flush_fallback
#define HRFI_TO_UNKNOWN \
+ STF_EXIT_BARRIER_SLOT; \
RFI_FLUSH_SLOT; \
hrfid; \
b hrfi_flush_fallback
@@ -249,6 +277,7 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
#define __EXCEPTION_PROLOG_1(area, extra, vec) \
OPT_SAVE_REG_TO_PACA(area+EX_PPR, r9, CPU_FTR_HAS_PPR); \
OPT_SAVE_REG_TO_PACA(area+EX_CFAR, r10, CPU_FTR_CFAR); \
+ INTERRUPT_TO_KERNEL; \
SAVE_CTR(r10, area); \
mfcr r9; \
extra(vec); \
@@ -187,6 +187,22 @@ label##3: \
FTR_ENTRY_OFFSET label##1b-label##3b; \
.popsection;
+#define STF_ENTRY_BARRIER_FIXUP_SECTION \
+953: \
+ .pushsection __stf_entry_barrier_fixup,"a"; \
+ .align 2; \
+954: \
+ FTR_ENTRY_OFFSET 953b-954b; \
+ .popsection;
+
+#define STF_EXIT_BARRIER_FIXUP_SECTION \
+955: \
+ .pushsection __stf_exit_barrier_fixup,"a"; \
+ .align 2; \
+956: \
+ FTR_ENTRY_OFFSET 955b-956b; \
+ .popsection;
+
#define RFI_FLUSH_FIXUP_SECTION \
951: \
.pushsection __rfi_flush_fixup,"a"; \
@@ -199,6 +215,9 @@ label##3: \
#ifndef __ASSEMBLY__
#include <linux/types.h>
+extern long stf_barrier_fallback;
+extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup;
+extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup;
extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;
void apply_feature_fixups(void);
@@ -12,6 +12,17 @@
extern unsigned long powerpc_security_features;
extern bool rfi_flush;
+/* These are bit flags */
+enum stf_barrier_type {
+ STF_BARRIER_NONE = 0x1,
+ STF_BARRIER_FALLBACK = 0x2,
+ STF_BARRIER_EIEIO = 0x4,
+ STF_BARRIER_SYNC_ORI = 0x8,
+};
+
+void setup_stf_barrier(void);
+void do_stf_barrier_fixups(enum stf_barrier_type types);
+
static inline void security_ftr_set(unsigned long feature)
{
powerpc_security_features |= feature;
@@ -825,7 +825,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_TM)
#endif
-EXC_REAL_MASKABLE(decrementer, 0x900, 0x80)
+EXC_REAL_OOL_MASKABLE(decrementer, 0x900, 0x80)
EXC_VIRT_MASKABLE(decrementer, 0x4900, 0x80, 0x900)
TRAMP_KVM(PACA_EXGEN, 0x900)
EXC_COMMON_ASYNC(decrementer_common, 0x900, timer_interrupt)
@@ -901,6 +901,7 @@ EXC_COMMON(trap_0b_common, 0xb00, unknow
mtctr r13; \
GET_PACA(r13); \
std r10,PACA_EXGEN+EX_R10(r13); \
+ INTERRUPT_TO_KERNEL; \
KVMTEST_PR(0xc00); /* uses r10, branch to do_kvm_0xc00_system_call */ \
HMT_MEDIUM; \
mfctr r9;
@@ -909,7 +910,8 @@ EXC_COMMON(trap_0b_common, 0xb00, unknow
#define SYSCALL_KVMTEST \
HMT_MEDIUM; \
mr r9,r13; \
- GET_PACA(r13);
+ GET_PACA(r13); \
+ INTERRUPT_TO_KERNEL;
#endif
#define LOAD_SYSCALL_HANDLER(reg) \
@@ -1434,6 +1436,19 @@ masked_##_H##interrupt: \
b .; \
MASKED_DEC_HANDLER(_H)
+TRAMP_REAL_BEGIN(stf_barrier_fallback)
+ std r9,PACA_EXRFI+EX_R9(r13)
+ std r10,PACA_EXRFI+EX_R10(r13)
+ sync
+ ld r9,PACA_EXRFI+EX_R9(r13)
+ ld r10,PACA_EXRFI+EX_R10(r13)
+ ori 31,31,0
+ .rept 14
+ b 1f
+1:
+ .endr
+ blr
+
TRAMP_REAL_BEGIN(rfi_flush_fallback)
SET_SCRATCH0(r13);
GET_PACA(r13);
@@ -8,6 +8,7 @@
#include <linux/device.h>
#include <linux/seq_buf.h>
+#include <asm/debugfs.h>
#include <asm/security_features.h>
@@ -86,3 +87,151 @@ ssize_t cpu_show_spectre_v2(struct devic
return s.len;
}
+
+/*
+ * 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)
+ 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 CONFIG_DEBUG_FS
+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 */
@@ -134,6 +134,20 @@ SECTIONS
#ifdef CONFIG_PPC64
. = ALIGN(8);
+ __stf_entry_barrier_fixup : AT(ADDR(__stf_entry_barrier_fixup) - LOAD_OFFSET) {
+ __start___stf_entry_barrier_fixup = .;
+ *(__stf_entry_barrier_fixup)
+ __stop___stf_entry_barrier_fixup = .;
+ }
+
+ . = ALIGN(8);
+ __stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) {
+ __start___stf_exit_barrier_fixup = .;
+ *(__stf_exit_barrier_fixup)
+ __stop___stf_exit_barrier_fixup = .;
+ }
+
+ . = ALIGN(8);
__rfi_flush_fixup : AT(ADDR(__rfi_flush_fixup) - LOAD_OFFSET) {
__start___rfi_flush_fixup = .;
*(__rfi_flush_fixup)
@@ -23,6 +23,7 @@
#include <asm/page.h>
#include <asm/sections.h>
#include <asm/setup.h>
+#include <asm/security_features.h>
#include <asm/firmware.h>
struct fixup_entry {
@@ -117,6 +118,120 @@ void do_feature_fixups(unsigned long val
}
#ifdef CONFIG_PPC_BOOK3S_64
+void do_stf_entry_barrier_fixups(enum stf_barrier_type types)
+{
+ unsigned int instrs[3], *dest;
+ long *start, *end;
+ int i;
+
+ start = PTRRELOC(&__start___stf_entry_barrier_fixup),
+ end = PTRRELOC(&__stop___stf_entry_barrier_fixup);
+
+ instrs[0] = 0x60000000; /* nop */
+ instrs[1] = 0x60000000; /* nop */
+ instrs[2] = 0x60000000; /* nop */
+
+ i = 0;
+ if (types & STF_BARRIER_FALLBACK) {
+ instrs[i++] = 0x7d4802a6; /* mflr r10 */
+ instrs[i++] = 0x60000000; /* branch patched below */
+ instrs[i++] = 0x7d4803a6; /* mtlr r10 */
+ } else if (types & STF_BARRIER_EIEIO) {
+ instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */
+ } else if (types & STF_BARRIER_SYNC_ORI) {
+ instrs[i++] = 0x7c0004ac; /* hwsync */
+ instrs[i++] = 0xe94d0000; /* ld r10,0(r13) */
+ instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */
+ }
+
+ for (i = 0; start < end; start++, i++) {
+ dest = (void *)start + *start;
+
+ pr_devel("patching dest %lx\n", (unsigned long)dest);
+
+ patch_instruction(dest, instrs[0]);
+
+ if (types & STF_BARRIER_FALLBACK)
+ patch_branch(dest + 1, (unsigned long)&stf_barrier_fallback,
+ BRANCH_SET_LINK);
+ else
+ patch_instruction(dest + 1, instrs[1]);
+
+ patch_instruction(dest + 2, instrs[2]);
+ }
+
+ printk(KERN_DEBUG "stf-barrier: patched %d entry locations (%s barrier)\n", i,
+ (types == STF_BARRIER_NONE) ? "no" :
+ (types == STF_BARRIER_FALLBACK) ? "fallback" :
+ (types == STF_BARRIER_EIEIO) ? "eieio" :
+ (types == (STF_BARRIER_SYNC_ORI)) ? "hwsync"
+ : "unknown");
+}
+
+void do_stf_exit_barrier_fixups(enum stf_barrier_type types)
+{
+ unsigned int instrs[6], *dest;
+ long *start, *end;
+ int i;
+
+ start = PTRRELOC(&__start___stf_exit_barrier_fixup),
+ end = PTRRELOC(&__stop___stf_exit_barrier_fixup);
+
+ instrs[0] = 0x60000000; /* nop */
+ instrs[1] = 0x60000000; /* nop */
+ instrs[2] = 0x60000000; /* nop */
+ instrs[3] = 0x60000000; /* nop */
+ instrs[4] = 0x60000000; /* nop */
+ instrs[5] = 0x60000000; /* nop */
+
+ i = 0;
+ if (types & STF_BARRIER_FALLBACK || types & STF_BARRIER_SYNC_ORI) {
+ if (cpu_has_feature(CPU_FTR_HVMODE)) {
+ instrs[i++] = 0x7db14ba6; /* mtspr 0x131, r13 (HSPRG1) */
+ instrs[i++] = 0x7db04aa6; /* mfspr r13, 0x130 (HSPRG0) */
+ } else {
+ instrs[i++] = 0x7db243a6; /* mtsprg 2,r13 */
+ instrs[i++] = 0x7db142a6; /* mfsprg r13,1 */
+ }
+ instrs[i++] = 0x7c0004ac; /* hwsync */
+ instrs[i++] = 0xe9ad0000; /* ld r13,0(r13) */
+ instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */
+ if (cpu_has_feature(CPU_FTR_HVMODE)) {
+ instrs[i++] = 0x7db14aa6; /* mfspr r13, 0x131 (HSPRG1) */
+ } else {
+ instrs[i++] = 0x7db242a6; /* mfsprg r13,2 */
+ }
+ } else if (types & STF_BARRIER_EIEIO) {
+ instrs[i++] = 0x7e0006ac; /* eieio + bit 6 hint */
+ }
+
+ for (i = 0; start < end; start++, i++) {
+ dest = (void *)start + *start;
+
+ pr_devel("patching dest %lx\n", (unsigned long)dest);
+
+ patch_instruction(dest, instrs[0]);
+ patch_instruction(dest + 1, instrs[1]);
+ patch_instruction(dest + 2, instrs[2]);
+ patch_instruction(dest + 3, instrs[3]);
+ patch_instruction(dest + 4, instrs[4]);
+ patch_instruction(dest + 5, instrs[5]);
+ }
+ printk(KERN_DEBUG "stf-barrier: patched %d exit locations (%s barrier)\n", i,
+ (types == STF_BARRIER_NONE) ? "no" :
+ (types == STF_BARRIER_FALLBACK) ? "fallback" :
+ (types == STF_BARRIER_EIEIO) ? "eieio" :
+ (types == (STF_BARRIER_SYNC_ORI)) ? "hwsync"
+ : "unknown");
+}
+
+
+void do_stf_barrier_fixups(enum stf_barrier_type types)
+{
+ do_stf_entry_barrier_fixups(types);
+ do_stf_exit_barrier_fixups(types);
+}
+
void do_rfi_flush_fixups(enum l1d_flush_type types)
{
unsigned int instrs[3], *dest;
@@ -130,6 +130,7 @@ static void __init pnv_setup_arch(void)
set_arch_panic_timeout(10, ARCH_PANIC_TIMEOUT);
pnv_setup_rfi_flush();
+ setup_stf_barrier();
/* Initialize SMP */
pnv_smp_init();
@@ -554,6 +554,7 @@ static void __init pSeries_setup_arch(vo
fwnmi_init();
pseries_setup_rfi_flush();
+ setup_stf_barrier();
/* By default, only probe PCI (can be overridden by rtas_pci) */
pci_add_flags(PCI_PROBE_ONLY);
This is a note to let you know that I've just added the patch titled powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: powerpc-64s-add-support-for-a-store-forwarding-barrier-at-kernel-entry-exit.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@vger.kernel.org> know about it. From foo@baz Sun May 27 15:47:18 CEST 2018 From: Michael Ellerman <mpe@ellerman.id.au> Date: Sat, 26 May 2018 14:27:49 +1000 Subject: powerpc/64s: Add support for a store forwarding barrier at kernel entry/exit To: greg@kroah.com Cc: stable@vger.kernel.org, tglx@linutronix.de, linuxppc-dev@ozlabs.org Message-ID: <20180526042749.5324-24-mpe@ellerman.id.au> From: Nicholas Piggin <npiggin@gmail.com> commit a048a07d7f4535baa4cbad6bc024f175317ab938 upstream. On some CPUs we can prevent a vulnerability related to store-to-load forwarding by preventing store forwarding between privilege domains, by inserting a barrier in kernel entry and exit paths. This is known to be the case on at least Power7, Power8 and Power9 powerpc CPUs. Barriers must be inserted generally before the first load after moving to a higher privilege, and after the last store before moving to a lower privilege, HV and PR privilege transitions must be protected. Barriers are added as patch sections, with all kernel/hypervisor entry points patched, and the exit points to lower privilge levels patched similarly to the RFI flush patching. Firmware advertisement is not implemented yet, so CPU flush types are hard coded. Thanks to Michal Suchánek for bug fixes and review. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com> Signed-off-by: Michael Neuling <mikey@neuling.org> Signed-off-by: Michal Suchánek <msuchanek@suse.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/powerpc/include/asm/exception-64s.h | 29 +++++ arch/powerpc/include/asm/feature-fixups.h | 19 +++ arch/powerpc/include/asm/security_features.h | 11 + arch/powerpc/kernel/exceptions-64s.S | 19 +++ arch/powerpc/kernel/security.c | 149 +++++++++++++++++++++++++++ arch/powerpc/kernel/vmlinux.lds.S | 14 ++ arch/powerpc/lib/feature-fixups.c | 115 ++++++++++++++++++++ arch/powerpc/platforms/powernv/setup.c | 1 arch/powerpc/platforms/pseries/setup.c | 1 9 files changed, 356 insertions(+), 2 deletions(-) Patches currently in stable-queue which might be from mpe@ellerman.id.au are queue-4.14/powerpc-64s-clear-pcr-on-boot.patch queue-4.14/powerpc-rfi-flush-differentiate-enabled-and-patched-flush-types.patch queue-4.14/powerpc-64s-fix-section-mismatch-warnings-from-setup_rfi_flush.patch queue-4.14/powerpc-pseries-fix-clearing-of-security-feature-flags.patch queue-4.14/powerpc-powernv-set-or-clear-security-feature-flags.patch queue-4.14/powerpc-64s-move-cpu_show_meltdown.patch queue-4.14/powerpc-rfi-flush-call-setup_rfi_flush-after-lpm-migration.patch queue-4.14/powerpc-pseries-set-or-clear-security-feature-flags.patch queue-4.14/powerpc-rfi-flush-make-it-possible-to-call-setup_rfi_flush-again.patch queue-4.14/powerpc-move-default-security-feature-flags.patch queue-4.14/powerpc-powernv-use-the-security-flags-in-pnv_setup_rfi_flush.patch queue-4.14/powerpc-add-security-feature-flags-for-spectre-meltdown.patch queue-4.14/powerpc-pseries-use-the-security-flags-in-pseries_setup_rfi_flush.patch queue-4.14/powerpc-64s-enhance-the-information-in-cpu_show_meltdown.patch queue-4.14/powerpc-64s-improve-rfi-l1-d-cache-flush-fallback.patch queue-4.14/powerpc-rfi-flush-always-enable-fallback-flush-on-pseries.patch queue-4.14/powerpc-rfi-flush-move-the-logic-to-avoid-a-redo-into-the-debugfs-code.patch queue-4.14/powerpc-pseries-restore-default-security-feature-flags-on-setup.patch queue-4.14/powerpc-pseries-add-new-h_get_cpu_characteristics-flags.patch queue-4.14/powerpc-64s-add-support-for-a-store-forwarding-barrier-at-kernel-entry-exit.patch queue-4.14/powerpc-64s-wire-up-cpu_show_spectre_v1.patch queue-4.14/powerpc-powernv-support-firmware-disable-of-rfi-flush.patch queue-4.14/powerpc-pseries-support-firmware-disable-of-rfi-flush.patch queue-4.14/powerpc-64s-wire-up-cpu_show_spectre_v2.patch