target/arm: Hyp mode R14 is shared with User and System

Hyp mode is an exception to the general rule that each AArch32
mode has its own r13, r14 and SPSR -- it has a banked r13 and
SPSR but shares its r14 with User and System mode. We were
incorrectly implementing it as banked, which meant that on
entry to Hyp mode r14 was 0 rather than the USR/SYS r14.

We provide a new function r14_bank_number() which is like
the existing bank_number() but provides the index into
env->banked_r14[]; bank_number() provides the index to use
for env->banked_r13[] and env->banked_cpsr[].

All the points in the code that were using bank_number()
to index into env->banked_r14[] are updated for consintency:
 * switch_mode() -- this is the only place where we fix
   an actual bug
 * aarch64_sync_32_to_64() and aarch64_sync_64_to_32():
   no behavioural change as we already special-cased Hyp R14
 * kvm32.c: no behavioural change since the guest can't ever
   be in Hyp mode, but conceptually the right thing to do
 * msr_banked()/mrs_banked(): we can never get to the case
   that accesses banked_r14[] with tgtmode == ARM_CPU_MODE_HYP,
   so no behavioural change

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20181109173553.22341-2-peter.maydell@linaro.org

1 files changed, 2 insertions, 2 deletions

diff --git a/target/arm/kvm32.c b/target/arm/kvm32.c
index 0f1e94c..cb3fb73 100644
--- a/target/arm/kvm32.c
+++ b/target/arm/kvm32.c
@@ -318,8 +318,8 @@ int kvm_arch_put_registers(CPUState *cs, int level)
         memcpy(env->usr_regs, env->regs + 8, 5 * sizeof(uint32_t));
     }
     env->banked_r13[bn] = env->regs[13];
-    env->banked_r14[bn] = env->regs[14];
     env->banked_spsr[bn] = env->spsr;
+    env->banked_r14[r14_bank_number(mode)] = env->regs[14];
 
     /* Now we can safely copy stuff down to the kernel */
     for (i = 0; i < ARRAY_SIZE(regs); i++) {
@@ -430,8 +430,8 @@ int kvm_arch_get_registers(CPUState *cs)
         memcpy(env->regs + 8, env->usr_regs, 5 * sizeof(uint32_t));
     }
     env->regs[13] = env->banked_r13[bn];
-    env->regs[14] = env->banked_r14[bn];
     env->spsr = env->banked_spsr[bn];
+    env->regs[14] = env->banked_r14[r14_bank_number(mode)];
 
     /* VFP registers */
     r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP;