Author: andrew Date: Wed May 1 17:12:49 2019 New Revision: 346996 URL: https://svnweb.freebsd.org/changeset/base/346996
Log: Restore x18 in efi_arch_leave. Some UEFI implementations trash this register and, as we use it as a platform register, the kernel doesn't save it before calling into the UEFI runtime services. As we have a copy in tpidr_el1 restore from there when exiting the EFI environment. PR: 237234, 237055 Reviewed by: manu Tested On: Ampere eMAG MFC after: 2 weeks Sponsored by: DARPA, AFRL Sponsored by: Ampere Computing (hardware) Differential Revision: https://reviews.freebsd.org/D20127 Modified: head/sys/arm64/arm64/efirt_machdep.c Modified: head/sys/arm64/arm64/efirt_machdep.c ============================================================================== --- head/sys/arm64/arm64/efirt_machdep.c Wed May 1 15:28:23 2019 (r346995) +++ head/sys/arm64/arm64/efirt_machdep.c Wed May 1 17:12:49 2019 (r346996) @@ -259,6 +259,16 @@ efi_arch_leave(void) { struct thread *td; + /* + * Restore the pcpu pointer. Some UEFI implementations trash it and + * we don't store it before calling into them. To fix this we need + * to restore it after returning to the kernel context. As reading + * curthread will access x18 we need to restore it before loading + * the thread pointer. + */ + __asm __volatile( + "mrs x18, tpidr_el1 \n" + ); td = curthread; __asm __volatile( "msr ttbr0_el1, %0 \n" _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
