target/s390x/tcg: Fix and improve the SACF instruction

The SET ADDRESS SPACE CONTROL FAST instruction is not privileged, it can be
used from problem space, too. Just the switching to the home address space
is privileged and should still generate a privilege exception. This bug is
e.g. causing programs like Java that use the "getcpu" vdso kernel function
to crash (see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=990417#26 ).

While we're at it, also check if DAT is not enabled. In that case the
instruction is supposed to generate a special operation exception.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/655
Message-Id: <20221201184443.136355-1-thuth@redhat.com>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

diff --git a/target/s390x/tcg/cc_helper.c b/target/s390x/tcg/cc_helper.c
index b2e8d3d9f5973611f1728a91b978791c393ab687..b36f8cdc8b9eaa264dcf86f630bef0d2cdb0fda8 100644 (file)
--- a/target/s390x/tcg/cc_helper.c
+++ b/target/s390x/tcg/cc_helper.c
@@ -487,6 +487,10 @@ void HELPER(sacf)(CPUS390XState *env, uint64_t a1)
 {
     HELPER_LOG("%s: %16" PRIx64 "\n", __func__, a1);
 
+    if (!(env->psw.mask & PSW_MASK_DAT)) {
+        tcg_s390_program_interrupt(env, PGM_SPECIAL_OP, GETPC());
+    }
+
     switch (a1 & 0xf00) {
     case 0x000:
         env->psw.mask &= ~PSW_MASK_ASC;
@@ -497,6 +501,9 @@ void HELPER(sacf)(CPUS390XState *env, uint64_t a1)
         env->psw.mask |= PSW_ASC_SECONDARY;
         break;
     case 0x300:
+        if ((env->psw.mask & PSW_MASK_PSTATE) != 0) {
+            tcg_s390_program_interrupt(env, PGM_PRIVILEGED, GETPC());
+        }
         env->psw.mask &= ~PSW_MASK_ASC;
         env->psw.mask |= PSW_ASC_HOME;
         break;

diff --git a/target/s390x/tcg/insn-data.h.inc b/target/s390x/tcg/insn-data.h.inc
index 7e952bdfc828b0434c9964e80b10527f26e202a9..54d4250c9f17e00cdadc19369155295b2963ab60 100644 (file)
--- a/target/s390x/tcg/insn-data.h.inc
+++ b/target/s390x/tcg/insn-data.h.inc
@@ -1365,7 +1365,7 @@
 /* SERVICE CALL LOGICAL PROCESSOR (PV hypercall) */
     F(0xb220, SERVC,   RRE,   Z,   r1_o, r2_o, 0, 0, servc, 0, IF_PRIV | IF_IO)
 /* SET ADDRESS SPACE CONTROL FAST */
-    F(0xb279, SACF,    S,     Z,   0, a2, 0, 0, sacf, 0, IF_PRIV)
+    C(0xb279, SACF,    S,     Z,   0, a2, 0, 0, sacf, 0)
 /* SET CLOCK */
     F(0xb204, SCK,     S,     Z,   0, m2_64a, 0, 0, sck, 0, IF_PRIV | IF_IO)
 /* SET CLOCK COMPARATOR */