Re: [PATCH] Arm32: MSR to SPSR needs qualification

[Julien Grall <julien.grall.oss@xxxxxxxxx>]

On Fri, 11 Jun 2021, 08:55 Jan Beulich, <jbeulich@xxxxxxxx> wrote:

The Arm ARM's description of MSR doesn't even allow for plain "SPSR"
here, and while gas accepts this, it takes it to mean SPSR_cf. Yet
surely all of SPSR wants updating on this path, not just the lowest and
highest 8 bits.

Can you provide a reference to the Arm Arm? This would help to navigate through the 8000 pages.

Cheers,

Fixes: dfcffb128be4 ("xen/arm32: SPSR_hyp/SPSR")
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/arm/arm32/entry.S
+++ b/xen/arch/arm/arm32/entry.S
@@ -395,7 +395,7 @@ return_to_hypervisor:
         ldr r11, [sp, #UREGS_pc]
         msr ELR_hyp, r11
         ldr r11, [sp, #UREGS_cpsr]
-        msr SPSR, r11
+        msr SPSR_cxsf, r11
 #ifdef CONFIG_ARM32_HARDEN_BRANCH_PREDICTOR
         /*
          * Hardening branch predictor may require to setup a different