[PATCH 03/21] linux-user/arm: Force v2 frames for fdpic

[Richard Henderson]

The value of get_os_release may be controlled by a command
line option.  Since fdpic was added in v4.14, and v2 frame
were added in v2.6.12, this makes no change under normal conditions.

Split out a helper function to perform the test.

Cc: qemu-...@nongnu.org
Signed-off-by: Richard Henderson <richard.hender...@linaro.org>
---
 linux-user/arm/signal.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/linux-user/arm/signal.c b/linux-user/arm/signal.c
index 32b68ee302..2d30345fc2 100644
--- a/linux-user/arm/signal.c
+++ b/linux-user/arm/signal.c
@@ -165,6 +165,18 @@ static inline int valid_user_regs(CPUARMState *regs)
     return 1;
 }
 
+static bool v2_frame(void)
+{
+    /*
+     * We do not create fdpic trampolines for v1 frames.
+     * Thus we force v2 frames, regardless of what uname says.
+     * Support for fdpic dates from Linux 4.14, so this is not
+     * really a behaviour change.
+     */
+    int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
+    return is_fdpic || get_osversion() >= 0x020612;
+}
+
 static void
 setup_sigcontext(struct target_sigcontext *sc, /*struct _fpstate *fpstate,*/
                  CPUARMState *env, abi_ulong mask)
@@ -422,7 +434,7 @@ sigsegv:
 void setup_frame(int usig, struct target_sigaction *ka,
                  target_sigset_t *set, CPUARMState *regs)
 {
-    if (get_osversion() >= 0x020612) {
+    if (v2_frame()) {
         setup_frame_v2(usig, ka, set, regs);
     } else {
         setup_frame_v1(usig, ka, set, regs);
@@ -516,7 +528,7 @@ void setup_rt_frame(int usig, struct target_sigaction *ka,
                     target_siginfo_t *info,
                     target_sigset_t *set, CPUARMState *env)
 {
-    if (get_osversion() >= 0x020612) {
+    if (v2_frame()) {
         setup_rt_frame_v2(usig, ka, info, set, env);
     } else {
         setup_rt_frame_v1(usig, ka, info, set, env);
@@ -734,7 +746,7 @@ badframe:
 
 long do_sigreturn(CPUARMState *env)
 {
-    if (get_osversion() >= 0x020612) {
+    if (v2_frame()) {
         return do_sigreturn_v2(env);
     } else {
         return do_sigreturn_v1(env);
@@ -823,7 +835,7 @@ badframe:
 
 long do_rt_sigreturn(CPUARMState *env)
 {
-    if (get_osversion() >= 0x020612) {
+    if (v2_frame()) {
         return do_rt_sigreturn_v2(env);
     } else {
         return do_rt_sigreturn_v1(env);
-- 
2.25.1