Commit 5ad09d2a authored by Marc Zyngier's avatar Marc Zyngier Committed by Greg Kroah-Hartman
Browse files

arm64: Call ARCH_WORKAROUND_2 on transitions between EL0 and EL1

commit 8e290624

 upstream.

In order for the kernel to protect itself, let's call the SSBD mitigation
implemented by the higher exception level (either hypervisor or firmware)
on each transition between userspace and kernel.

We must take the PSCI conduit into account in order to target the
right exception level, hence the introduction of a runtime patching
callback.
Reviewed-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarJulien Grall <julien.grall@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1de27191
......@@ -228,6 +228,30 @@ static int qcom_enable_link_stack_sanitization(void *data)
}
#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 MIDR_RANGE(model, min, max) \
.def_scope = SCOPE_LOCAL_CPU, \
.matches = is_affected_midr_range, \
......
......@@ -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
......@@ -301,6 +321,8 @@ alternative_if ARM64_WORKAROUND_845719
alternative_else_nop_endif
#endif
3:
apply_ssbd 0
.endif
msr elr_el1, x21 // set up the return data
......
......@@ -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>
......
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