target/arm: Fix A64 LDRA immediate decode

In commit be23a04 in the conversion to decodetree we broke the
decoding of the immediate value in the LDRA instruction.  This should
be a 10 bit signed value that is scaled by 8, but in the conversion
we incorrectly ended up scaling it only by 2.  Fix the scaling
factor.

Cc: qemu-stable@nongnu.org
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1970
Fixes: be23a04 ("target/arm: Convert load (pointer auth) insns to decodetree")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20231106113445.1163063-1-peter.maydell@linaro.org
(cherry picked from commit 5722fc4)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

target/arm/tcg/a64.decode

@@ -461,7 +461,7 @@ LDAPR           sz:2 111 0 00 1 0 1 11111 1100 00 rn:5 rt:5
 # Load/store register (pointer authentication)
 
 # LDRA immediate is 10 bits signed and scaled, but the bits aren't all contiguous
-%ldra_imm       22:s1 12:9 !function=times_2
+%ldra_imm       22:s1 12:9 !function=times_8
 
 LDRA            11 111 0 00 m:1 . 1 ......... w:1 1 rn:5 rt:5 imm=%ldra_imm
 

target/arm/tcg/translate.h

@@ -203,6 +203,11 @@ static inline int times_4(DisasContext *s, int x)
     return x * 4;
 }
 
+static inline int times_8(DisasContext *s, int x)
+{
+    return x * 8;
+}
+
 static inline int times_2_plus_1(DisasContext *s, int x)
 {
     return x * 2 + 1;