[Xen-changelog] [xen master] xen/arm: Allow secondary cpus to start in THUMB

[patchbot@xxxxxxx]

commit 6b8d02fe423f799f653dd5c02db973cba7b449fe
Author:     Julien Grall <julien.grall@xxxxxxxxxx>
AuthorDate: Thu Jul 25 16:21:31 2013 +0100
Commit:     Ian Campbell <ian.campbell@xxxxxxxxxx>
CommitDate: Mon Jul 29 16:54:48 2013 +0100

    xen/arm: Allow secondary cpus to start in THUMB
    
    Unlike bx, eret will not update the instruction set (THUMB,ARM) according to
    the return address. This will result to an unpredicable behaviour for the
    processor if the address doesn't match the right instruction set.
    
    When the kernel is compiled with THUMB2, THUMB bit needs to be set in CPSR
    for the secondary cpus.
    
    Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
    Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/psci.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/xen/arch/arm/psci.c b/xen/arch/arm/psci.c
index 18feead..200769c 100644
--- a/xen/arch/arm/psci.c
+++ b/xen/arch/arm/psci.c
@@ -24,6 +24,7 @@ int do_psci_cpu_on(uint32_t vcpuid, register_t entry_point)
     struct domain *d = current->domain;
     struct vcpu_guest_context *ctxt;
     int rc;
+    int is_thumb = entry_point & 1;
 
     if ( (vcpuid < 0) || (vcpuid >= MAX_VIRT_CPUS) )
         return PSCI_EINVAL;
@@ -31,6 +32,10 @@ int do_psci_cpu_on(uint32_t vcpuid, register_t entry_point)
     if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
         return PSCI_EINVAL;
 
+    /* THUMB set is not allowed with 64-bit domain */
+    if ( is_pv64_domain(d) && is_thumb )
+        return PSCI_EINVAL;
+
     if ( (ctxt = alloc_vcpu_guest_context()) == NULL )
         return PSCI_DENIED;
 
@@ -43,6 +48,9 @@ int do_psci_cpu_on(uint32_t vcpuid, register_t entry_point)
     ctxt->ttbr1 = 0;
     ctxt->ttbcr = 0; /* Defined Reset Value */
     ctxt->user_regs.cpsr = PSR_GUEST_INIT;
+    /* Start the VCPU with THUMB set if it's requested by the kernel */
+    if ( is_thumb )
+        ctxt->user_regs.cpsr |= PSR_THUMB;
     ctxt->flags = VGCF_online;
 
     domain_lock(d);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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