[PATCH] disas/riscv: Further correction to LUI disassembly

[Richard Bagley]

The recent commit 36df75a0a9 corrected one aspect of LUI disassembly
by recovering the immediate argument from the result of LUI with a
shift right by 12. However, the shift right will left-fill with the
sign. By applying a mask we recover an unsigned representation of the
20-bit field (which includes a sign bit).

Example:
0xfffff000 >> 12 = 0xffffffff
0xfffff000 >> 12 & 0xfffff = 0x000fffff

Fixes: 36df75a0a9 ("riscv/disas: Fix disas output of upper immediates")
Signed-off-by: Richard Bagley <rbagley@ventanamicro.com>
---
 disas/riscv.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/disas/riscv.c b/disas/riscv.c
index 4023e3fc65..690eb4a1ac 100644
--- a/disas/riscv.c
+++ b/disas/riscv.c
@@ -4723,9 +4723,12 @@ static void format_inst(char *buf, size_t buflen, size_t 
tab, rv_decode *dec)
             break;
         case 'U':
             fmt++;
-            snprintf(tmp, sizeof(tmp), "%d", dec->imm >> 12);
-            append(buf, tmp, buflen);
-            if (*fmt == 'o') {
+            if (*fmt == 'i') {
+                snprintf(tmp, sizeof(tmp), "%d", dec->imm >> 12 & 0xfffff);
+                append(buf, tmp, buflen);
+            } else if (*fmt == 'o') {
+                snprintf(tmp, sizeof(tmp), "%d", dec->imm >> 12);
+                append(buf, tmp, buflen);
                 while (strlen(buf) < tab * 2) {
                     append(buf, " ", buflen);
                 }
-- 
2.34.1