[Stable-8.2.7 53/53] target/hppa: Fix PSW V-bit packaging in cpu_hppa_get for hppa64

[Michael Tokarev]

From: Helge Deller <deller@gmx.de>

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>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Fixes: 931adff31478 ("target/hppa: Update cpu_hppa_get/put_psw for hppa64")
Cc: qemu-stable@nongnu.org # v8.2+
(cherry picked from commit ead5078cf1a5f11d16e3e8462154c859620bcc7e)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(Mjt: context fixup in target/hppa/helper.c due to lack of
 v9.0.0-688-gebc9401a4067 "target/hppa: Split PSW X and B into their own field")

diff --git a/target/hppa/cpu.h b/target/hppa/cpu.h
index 9556e95fab..e29e69dc31 100644
--- a/target/hppa/cpu.h
+++ b/target/hppa/cpu.h
@@ -188,7 +188,7 @@ typedef struct CPUArchState {
 
     target_ulong psw;        /* All psw bits except the following:  */
     target_ulong psw_n;      /* boolean */
-    target_long psw_v;       /* in most significant bit */
+    target_long psw_v;       /* in bit 31 */
 
     /* Splitting the carry-borrow field into the MSB and "the rest", allows
      * for "the rest" to be deleted when it is unused, but the MSB is in use.
diff --git a/target/hppa/helper.c b/target/hppa/helper.c
index 859644c47a..9e35b65f29 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;
 
     return psw;
-- 
2.39.2