diff options
Diffstat (limited to 'arch/arm64/kernel/boot.S')
| -rw-r--r-- | arch/arm64/kernel/boot.S | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/arm64/kernel/boot.S b/arch/arm64/kernel/boot.S index 615be06..d8b888f 100644 --- a/arch/arm64/kernel/boot.S +++ b/arch/arm64/kernel/boot.S @@ -30,6 +30,20 @@ ENTRY(tb_boot_linux) mov x2, xzr mov x3, xzr + /* + * raise to EL2 for the payload when EL2 exists, the kernel + * prefers it there (booting.rst). hvc from EL1 lands in our + * EL2 vector slot, the dispatcher sees the non PSCI function + * id, stages ELR_EL2 with the entry and erets to the payload. + * on an EL1 only machine this is a straight branch. + */ + mrs x9, CurrentEL + lsr x9, x9, #2 + cmp x9, #2 + b.lt 5f + hvc #0 +5: + /* MMU off, caches off, the kernel sets up its own state */ mrs x9, sctlr_el1 bic x9, x9, #(1 << 0) /* M, MMU */ @@ -38,6 +52,15 @@ ENTRY(tb_boot_linux) msr sctlr_el1, x9 isb + /* + * if we entered at EL2, the kernel prefers it there. the C + * runtime ran at EL1 for semihosting, so raise back: hvc to + * our own EL2 vectors would need a live handler, instead the + * entry saved the EL2 state and we simply reenter it through + * the tb_el2_trampoline the entry installed. + */ + + br x8 ENDPROC(tb_boot_linux) .popsection |