From: Ilya Leoshkevich <iii@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>, Thomas Huth <thuth@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
David Hildenbrand <david@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Peter Maydell <peter.maydell@linaro.org>,
Max Filippov <jcmvbkbc@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>,
qemu-s390x@nongnu.org, qemu-arm@nongnu.org,
qemu-devel@nongnu.org, Ilya Leoshkevich <iii@linux.ibm.com>
Subject: [PATCH v4 1/4] target/s390x: Fix translation exception on illegal instruction
Date: Thu, 15 Apr 2021 15:03:02 +0200 [thread overview]
Message-ID: <20210415130305.28640-2-iii@linux.ibm.com> (raw)
In-Reply-To: <20210415130305.28640-1-iii@linux.ibm.com>
Hitting an uretprobe in a s390x TCG guest causes a SIGSEGV. What
happens is:
* uretprobe maps a userspace page containing an invalid instruction.
* uretprobe replaces the target function's return address with the
address of that page.
* When tb_gen_code() is called on that page, tb->size ends up being 0
(because the page starts with the invalid instruction), which causes
virt_page2 to point to the previous page.
* The previous page is not mapped, so this causes a spurious
translation exception.
tb->size must never be 0: even if there is an illegal instruction, the
instruction bytes that have been looked at must count towards tb->size.
So adjust s390x's translate_one() to act this way for both illegal
instructions and instructions that are known to generate exceptions.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
target/s390x/translate.c | 16 +++++++++++-----
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/target/s390x/translate.c b/target/s390x/translate.c
index 4f953ddfba..e243624d2a 100644
--- a/target/s390x/translate.c
+++ b/target/s390x/translate.c
@@ -6412,7 +6412,8 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
qemu_log_mask(LOG_UNIMP, "unimplemented opcode 0x%02x%02x\n",
s->fields.op, s->fields.op2);
gen_illegal_opcode(s);
- return DISAS_NORETURN;
+ ret = DISAS_NORETURN;
+ goto out;
}
#ifndef CONFIG_USER_ONLY
@@ -6428,7 +6429,8 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
/* privileged instruction */
if ((s->base.tb->flags & FLAG_MASK_PSTATE) && (insn->flags & IF_PRIV)) {
gen_program_exception(s, PGM_PRIVILEGED);
- return DISAS_NORETURN;
+ ret = DISAS_NORETURN;
+ goto out;
}
/* if AFP is not enabled, instructions and registers are forbidden */
@@ -6455,7 +6457,8 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
}
if (dxc) {
gen_data_exception(dxc);
- return DISAS_NORETURN;
+ ret = DISAS_NORETURN;
+ goto out;
}
}
@@ -6463,7 +6466,8 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
if (insn->flags & IF_VEC) {
if (!((s->base.tb->flags & FLAG_MASK_VECTOR))) {
gen_data_exception(0xfe);
- return DISAS_NORETURN;
+ ret = DISAS_NORETURN;
+ goto out;
}
}
@@ -6484,7 +6488,8 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
(insn->spec & SPEC_r1_f128 && !is_fp_pair(get_field(s, r1))) ||
(insn->spec & SPEC_r2_f128 && !is_fp_pair(get_field(s, r2)))) {
gen_program_exception(s, PGM_SPECIFICATION);
- return DISAS_NORETURN;
+ ret = DISAS_NORETURN;
+ goto out;
}
}
@@ -6544,6 +6549,7 @@ static DisasJumpType translate_one(CPUS390XState *env, DisasContext *s)
}
#endif
+out:
/* Advance to the next instruction. */
s->base.pc_next = s->pc_tmp;
return ret;
--
2.29.2
next prev parent reply other threads:[~2021-04-15 13:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 13:03 [PATCH v4 0/4] accel/tcg: Make sure that tb->size != 0 after translation Ilya Leoshkevich
2021-04-15 13:03 ` Ilya Leoshkevich [this message]
2021-04-15 13:03 ` [PATCH v4 2/4] target/arm: Make sure that commpage's tb->size != 0 Ilya Leoshkevich
2021-04-16 14:10 ` Peter Maydell
2021-04-16 15:38 ` Ilya Leoshkevich
2021-04-15 13:03 ` [PATCH v4 3/4] target/xtensa: Make sure that " Ilya Leoshkevich
2021-04-15 20:14 ` Max Filippov
2021-04-15 13:03 ` [PATCH v4 4/4] accel/tcg: Assert that tb->size != 0 after translation Ilya Leoshkevich
2021-04-15 15:39 ` [PATCH v4 0/4] accel/tcg: Make sure " Cornelia Huck
2021-04-16 11:53 ` Ilya Leoshkevich
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