[PATCH] target/hppa: Fix PSW V-bit packaging in cpu_hppa_get for hppa64

[Helge Deller <deller@kernel.org>]

While adding hppa64 support, the psw_v variable got extended from 32 to 64
bits.  So, when packaging the PSW-V bit from the psw_v variable for interrupt
processing, check bit 31 instead the 63th (sign) bit.

This fixes a hard to find Linux kernel boot issue where the loss of the PSW-V
bit due to an ITLB interruption in the middle of a series of ds/addc
instructions (from the divU milicode library) generated the wrong division
result and thus triggered a Linux kernel crash.

Link: https://lore.kernel.org/lkml/718b8afe-222f-4b3a-96d3-93af0e4ceff1@roeck-us.net/
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64")

diff --git a/target/hppa/helper.c b/target/hppa/helper.c
index b79ddd8184..d4b1a3cd5a 100644
--- a/target/hppa/helper.c
+++ b/target/hppa/helper.c
@@ -53,7 +53,7 @@ target_ulong cpu_hppa_get_psw(CPUHPPAState *env)
     }
 
     psw |= env->psw_n * PSW_N;
-    psw |= (env->psw_v < 0) * PSW_V;
+    psw |= ((env->psw_v >> 31) & 1) * PSW_V;
     psw |= env->psw | env->psw_xb;
 
     return psw;