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-rw-r--r--arch/arm64/kernel/cpu_errata.c24
-rw-r--r--arch/arm64/kernel/entry.S22
-rw-r--r--include/linux/arm-smccc.h5
3 files changed, 51 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c
index a900befadfe8..c1eda6be7758 100644
--- a/arch/arm64/kernel/cpu_errata.c
+++ b/arch/arm64/kernel/cpu_errata.c
@@ -232,6 +232,30 @@ enable_smccc_arch_workaround_1(const struct arm64_cpu_capabilities *entry)
}
#endif /* CONFIG_HARDEN_BRANCH_PREDICTOR */
+#ifdef CONFIG_ARM64_SSBD
+void __init arm64_update_smccc_conduit(struct alt_instr *alt,
+ __le32 *origptr, __le32 *updptr,
+ int nr_inst)
+{
+ u32 insn;
+
+ BUG_ON(nr_inst != 1);
+
+ switch (psci_ops.conduit) {
+ case PSCI_CONDUIT_HVC:
+ insn = aarch64_insn_get_hvc_value();
+ break;
+ case PSCI_CONDUIT_SMC:
+ insn = aarch64_insn_get_smc_value();
+ break;
+ default:
+ return;
+ }
+
+ *updptr = cpu_to_le32(insn);
+}
+#endif /* CONFIG_ARM64_SSBD */
+
#define CAP_MIDR_RANGE(model, v_min, r_min, v_max, r_max) \
.matches = is_affected_midr_range, \
.midr_range = MIDR_RANGE(model, v_min, r_min, v_max, r_max)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ec2ee720e33e..f33e6aed3037 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -18,6 +18,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
+#include <linux/arm-smccc.h>
#include <linux/init.h>
#include <linux/linkage.h>
@@ -137,6 +138,18 @@ alternative_else_nop_endif
add \dst, \dst, #(\sym - .entry.tramp.text)
.endm
+ // This macro corrupts x0-x3. It is the caller's duty
+ // to save/restore them if required.
+ .macro apply_ssbd, state
+#ifdef CONFIG_ARM64_SSBD
+ mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
+ mov w1, #\state
+alternative_cb arm64_update_smccc_conduit
+ nop // Patched to SMC/HVC #0
+alternative_cb_end
+#endif
+ .endm
+
.macro kernel_entry, el, regsize = 64
.if \regsize == 32
mov w0, w0 // zero upper 32 bits of x0
@@ -163,6 +176,13 @@ alternative_else_nop_endif
ldr x19, [tsk, #TSK_TI_FLAGS] // since we can unmask debug
disable_step_tsk x19, x20 // exceptions when scheduling.
+ apply_ssbd 1
+
+#ifdef CONFIG_ARM64_SSBD
+ ldp x0, x1, [sp, #16 * 0]
+ ldp x2, x3, [sp, #16 * 1]
+#endif
+
mov x29, xzr // fp pointed to user-space
.else
add x21, sp, #S_FRAME_SIZE
@@ -303,6 +323,8 @@ alternative_if ARM64_WORKAROUND_845719
alternative_else_nop_endif
#endif
3:
+ apply_ssbd 0
+
.endif
msr elr_el1, x21 // set up the return data
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index c89da86de99f..ca1d2cc2cdfa 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -80,6 +80,11 @@
ARM_SMCCC_SMC_32, \
0, 0x8000)
+#define ARM_SMCCC_ARCH_WORKAROUND_2 \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_32, \
+ 0, 0x7fff)
+
#ifndef __ASSEMBLY__
#include <linux/linkage.h>