linux-user/hppa: Add signal trampoline for hppa target

In Linux kernel v5.18 the vDSO for signal trampoline was added.
This code mimiks the bare minimum of this vDSO and thus avoids that the
parisc emulation needs executable stacks.

Signed-off-by: Helge Deller <deller@gmx.de>
Message-Id: <20220924114501.21767-4-deller@gmx.de>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

1 files changed, 31 insertions, 10 deletions

diff --git a/linux-user/hppa/signal.c b/linux-user/hppa/signal.c
index 962f551c04..396e310dc9 100644
--- a/linux-user/hppa/signal.c
+++ b/linux-user/hppa/signal.c
@@ -41,7 +41,7 @@ struct target_ucontext {
 };
 
 struct target_rt_sigframe {
-    abi_uint tramp[9];
+    abi_uint tramp[2];  /* syscall restart return address */
     target_siginfo_t info;
     struct target_ucontext uc;
     /* hidden location of upper halves of pa2.0 64-bit gregs */
@@ -101,9 +101,15 @@ static void restore_sigcontext(CPUArchState *env, struct target_sigcontext *sc)
     __get_user(env->cr[CR_SAR], &sc->sc_sar);
 }
 
-/* No, this doesn't look right, but it's copied straight from the kernel.  */
+#if TARGET_ABI_BITS == 32
+#define SIGFRAME                64
+#define FUNCTIONCALLFRAME       48
+#else
+#define SIGFRAME                128
+#define FUNCTIONCALLFRAME       96
+#endif
 #define PARISC_RT_SIGFRAME_SIZE32 \
-    ((sizeof(struct target_rt_sigframe) + 48 + 64) & -64)
+    ((sizeof(struct target_rt_sigframe) + FUNCTIONCALLFRAME + SIGFRAME) & -SIGFRAME)
 
 void setup_rt_frame(int sig, struct target_sigaction *ka,
                     target_siginfo_t *info,
@@ -118,7 +124,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     if ((ka->sa_flags & TARGET_SA_ONSTACK) && !sas_ss_flags(sp)) {
         sp = (ts->sigaltstack_used.ss_sp + 0x7f) & ~0x3f;
     }
-    frame_addr = QEMU_ALIGN_UP(sp, 64);
+    frame_addr = QEMU_ALIGN_UP(sp, SIGFRAME);
     sp = frame_addr + PARISC_RT_SIGFRAME_SIZE32;
 
     trace_user_setup_rt_frame(env, frame_addr);
@@ -139,14 +145,9 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
 
     setup_sigcontext(&frame->uc.tuc_mcontext, env);
 
-    __put_user(0x34190000, frame->tramp + 0); /* ldi 0,%r25 */
-    __put_user(0x3414015a, frame->tramp + 1); /* ldi __NR_rt_sigreturn,%r20 */
-    __put_user(0xe4008200, frame->tramp + 2); /* be,l 0x100(%sr2,%r0) */
-    __put_user(0x08000240, frame->tramp + 3); /* nop */
-
     unlock_user_struct(frame, frame_addr, 1);
 
-    env->gr[2] = h2g(frame->tramp);
+    env->gr[2] = default_rt_sigreturn;
     env->gr[30] = sp;
     env->gr[26] = sig;
     env->gr[25] = h2g(&frame->info);
@@ -197,3 +198,23 @@ long do_rt_sigreturn(CPUArchState *env)
     force_sig(TARGET_SIGSEGV);
     return -QEMU_ESIGRETURN;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 6*4, 0);
+    abi_ulong SIGFRAME_CONTEXT_REGS32;
+    assert(tramp != NULL);
+
+    SIGFRAME_CONTEXT_REGS32 = offsetof(struct target_rt_sigframe, uc.tuc_mcontext);
+    SIGFRAME_CONTEXT_REGS32 -= PARISC_RT_SIGFRAME_SIZE32;
+
+    __put_user(SIGFRAME_CONTEXT_REGS32, tramp + 0);
+    __put_user(0x08000240, tramp + 1);  /* nop - b/c dwarf2 unwind routines */
+    __put_user(0x34190000, tramp + 2);  /* ldi 0, %r25 (in_syscall=0) */
+    __put_user(0x3414015a, tramp + 3);  /* ldi __NR_rt_sigreturn, %r20 */
+    __put_user(0xe4008200, tramp + 4);  /* ble 0x100(%sr2, %r0) */
+    __put_user(0x08000240, tramp + 5);  /* nop */
+
+    default_rt_sigreturn = (sigtramp_page + 8) | 3;
+    unlock_user(tramp, sigtramp_page, 6*4);
+}