[PATCH v3 1/4] target/arm: Use bit 55 explicitly for pauth

[Richard Henderson]

The psuedocode in aarch64/functions/pac/auth/Auth and
aarch64/functions/pac/strip/Strip always uses bit 55 for
extfield and do not consider if the current regime has 2 ranges.

Suggested-by: Peter Maydell <address@hidden>
Signed-off-by: Richard Henderson <address@hidden>
---
 target/arm/pauth_helper.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/target/arm/pauth_helper.c b/target/arm/pauth_helper.c
index 9746e32bf8..b909630317 100644
--- a/target/arm/pauth_helper.c
+++ b/target/arm/pauth_helper.c
@@ -320,7 +320,8 @@ static uint64_t pauth_addpac(CPUARMState *env, uint64_t 
ptr, uint64_t modifier,
 
 static uint64_t pauth_original_ptr(uint64_t ptr, ARMVAParameters param)
 {
-    uint64_t extfield = -param.select;
+    /* Note that bit 55 is used whether or not the regime has 2 ranges. */
+    uint64_t extfield = sextract64(ptr, 55, 1);
     int bot_pac_bit = 64 - param.tsz;
     int top_pac_bit = 64 - 8 * param.tbi;
 
-- 
2.20.1