From 3319e2fd5b151695f30f8574bbd9250f86a96e16 Mon Sep 17 00:00:00 2001
From: Laurent Vivier <lvivier@redhat.com>
Date: Thu, 3 May 2018 14:59:08 +0100
Subject: tcg: workaround branch instruction overflow in tcg_out_qemu_ld/st

RH-Author: Laurent Vivier <lvivier@redhat.com>
Message-id: <20180503145908.8110-1-lvivier@redhat.com>
Patchwork-id: 80019
O-Subject: [qemu-kvm RHEL8/virt212 PATCH] tcg: workaround branch instruction overflow in tcg_out_qemu_ld/st
Bugzilla: 1571145
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Serhii Popovych <spopovyc@redhat.com>
RH-Acked-by: David Gibson <dgibson@redhat.com>

BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1571145
BRANCH:rhel8/master-2.12.0
UPSTREAM: https://github.com/qemu/qemu/commit/6001f7729e12dd1d810291e4cbf83cee8e07441d
BREW: https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=15973114

ppc64 uses a BC instruction to call the tcg_out_qemu_ld/st
slow path. BC instruction uses a relative address encoded
on 14 bits.

The slow path functions are added at the end of the generated
instructions buffer, in the reverse order of the callers.
So more we have slow path functions more the distance between
the caller (BC) and the function increases.

This patch changes the behavior to generate the functions in
the same order of the callers.

Cc: qemu-stable@nongnu.org
Fixes: 15fa08f845 ("tcg: Dynamically allocate TCGOps")
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20180429235840.16659-1-lvivier@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
(cherry picked from commit 6001f7729e12dd1d810291e4cbf83cee8e07441d)
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 tcg/tcg-ldst.inc.c | 8 ++++----
 tcg/tcg.c          | 2 +-
 tcg/tcg.h          | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/tcg/tcg-ldst.inc.c b/tcg/tcg-ldst.inc.c
index 0e14cf4..47f41b9 100644
--- a/tcg/tcg-ldst.inc.c
+++ b/tcg/tcg-ldst.inc.c
@@ -30,7 +30,7 @@ typedef struct TCGLabelQemuLdst {
     TCGReg datahi_reg;      /* reg index for high word to be loaded or stored */
     tcg_insn_unit *raddr;   /* gen code addr of the next IR of qemu_ld/st IR */
     tcg_insn_unit *label_ptr[2]; /* label pointers to be updated */
-    struct TCGLabelQemuLdst *next;
+    QSIMPLEQ_ENTRY(TCGLabelQemuLdst) next;
 } TCGLabelQemuLdst;
 
 
@@ -46,7 +46,7 @@ static bool tcg_out_ldst_finalize(TCGContext *s)
     TCGLabelQemuLdst *lb;
 
     /* qemu_ld/st slow paths */
-    for (lb = s->ldst_labels; lb != NULL; lb = lb->next) {
+    QSIMPLEQ_FOREACH(lb, &s->ldst_labels, next) {
         if (lb->is_ld) {
             tcg_out_qemu_ld_slow_path(s, lb);
         } else {
@@ -72,7 +72,7 @@ static inline TCGLabelQemuLdst *new_ldst_label(TCGContext *s)
 {
     TCGLabelQemuLdst *l = tcg_malloc(sizeof(*l));
 
-    l->next = s->ldst_labels;
-    s->ldst_labels = l;
+    QSIMPLEQ_INSERT_TAIL(&s->ldst_labels, l, next);
+
     return l;
 }
diff --git a/tcg/tcg.c b/tcg/tcg.c
index bb24526..b84850b 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -3324,7 +3324,7 @@ int tcg_gen_code(TCGContext *s, TranslationBlock *tb)
     s->code_ptr = tb->tc.ptr;
 
 #ifdef TCG_TARGET_NEED_LDST_LABELS
-    s->ldst_labels = NULL;
+    QSIMPLEQ_INIT(&s->ldst_labels);
 #endif
 #ifdef TCG_TARGET_NEED_POOL_LABELS
     s->pool_labels = NULL;
diff --git a/tcg/tcg.h b/tcg/tcg.h
index 30896ca..a3076c5 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -699,7 +699,7 @@ struct TCGContext {
 
     /* These structures are private to tcg-target.inc.c.  */
 #ifdef TCG_TARGET_NEED_LDST_LABELS
-    struct TCGLabelQemuLdst *ldst_labels;
+    QSIMPLEQ_HEAD(ldst_labels, TCGLabelQemuLdst) ldst_labels;
 #endif
 #ifdef TCG_TARGET_NEED_POOL_LABELS
     struct TCGLabelPoolData *pool_labels;
-- 
1.8.3.1