Merge remote-tracking branch 'remotes/vivier/tags/linux-user-for-6.2-pull-request' into staging

Pull request linux-user 20211004

Move signal trampolines to new page

# gpg: Signature made Mon 04 Oct 2021 12:43:53 AM PDT
# gpg:                using RSA key CD2F75DDC8E3A4DC2E4F5173F30C38BD3F2FBE3C
# gpg:                issuer "[email protected]"
# gpg: Good signature from "Laurent Vivier <[email protected]>" [full]
# gpg:                 aka "Laurent Vivier <[email protected]>" [full]
# gpg:                 aka "Laurent Vivier (Red Hat) <[email protected]>" [full]

* remotes/vivier/tags/linux-user-for-6.2-pull-request: (26 commits)
  tests/tcg/multiarch: Re-enable signals test for most guests
  linux-user: Remove default for TARGET_ARCH_HAS_SIGTRAMP_PAGE
  linux-user/xtensa: Implement setup_sigtramp
  linux-user/sparc: Implement setup_sigtramp
  linux-user/sh4: Implement setup_sigtramp
  linux-user/s390x: Implement setup_sigtramp
  linux-user/riscv: Implement setup_sigtramp
  linux-user/ppc: Implement setup_sigtramp
  linux-user/ppc: Simplify encode_trampoline
  linux-user/openrisc: Implement setup_sigtramp
  linux-user/nios2: Document non-use of setup_sigtramp
  linux-user/mips: Implement setup_sigtramp
  linux-user/mips: Tidy install_sigtramp
  linux-user/microblaze: Implement setup_sigtramp
  linux-user/m68k: Implement setup_sigtramp
  linux-user/x86_64: Raise SIGSEGV if SA_RESTORER not set
  linux-user/i386: Implement setup_sigtramp
  linux-user/hppa: Document non-use of setup_sigtramp
  linux-user/hexagon: Implement setup_sigtramp
  linux-user/cris: Implement setup_sigtramp
  ...

Signed-off-by: Richard Henderson <[email protected]>

Author: rth7680

linux-user/aarch64/signal.c

@@ -109,7 +109,6 @@ struct target_rt_sigframe {
 struct target_rt_frame_record {
     uint64_t fp;
     uint64_t lr;
-    uint32_t tramp[2];
 };
 
 static void target_setup_general_frame(struct target_rt_sigframe *sf,
@@ -461,9 +460,9 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
     layout.total_size = MAX(layout.total_size,
                             sizeof(struct target_rt_sigframe));
 
-    /* Reserve space for the return code.  On a real system this would
-     * be within the VDSO.  So, despite the name this is not a "real"
-     * record within the frame.
+    /*
+     * Reserve space for the standard frame unwind pair: fp, lr.
+     * Despite the name this is not a "real" record within the frame.
      */
     fr_ofs = layout.total_size;
     layout.total_size += sizeof(struct target_rt_frame_record);
@@ -496,15 +495,7 @@ static void target_setup_frame(int usig, struct target_sigaction *ka,
     if (ka->sa_flags & TARGET_SA_RESTORER) {
         return_addr = ka->sa_restorer;
     } else {
-        /*
-         * mov x8,#__NR_rt_sigreturn; svc #0
-         * Since these are instructions they need to be put as little-endian
-         * regardless of target default or current CPU endianness.
-         */
-        __put_user_e(0xd2801168, &fr->tramp[0], le);
-        __put_user_e(0xd4000001, &fr->tramp[1], le);
-        return_addr = frame_addr + fr_ofs
-            + offsetof(struct target_rt_frame_record, tramp);
+        return_addr = default_rt_sigreturn;
     }
     env->xregs[0] = usig;
     env->xregs[29] = frame_addr + fr_ofs;
@@ -577,3 +568,20 @@ long do_sigreturn(CPUARMState *env)
 {
     return do_rt_sigreturn(env);
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 8, 0);
+    assert(tramp != NULL);
+
+    /*
+     * mov x8,#__NR_rt_sigreturn; svc #0
+     * Since these are instructions they need to be put as little-endian
+     * regardless of target default or current CPU endianness.
+     */
+    __put_user_e(0xd2801168, &tramp[0], le);
+    __put_user_e(0xd4000001, &tramp[1], le);
+
+    default_rt_sigreturn = sigtramp_page;
+    unlock_user(tramp, sigtramp_page, 8);
+}

linux-user/aarch64/target_signal.h

@@ -25,4 +25,6 @@ typedef struct target_sigaltstack {
 #define TARGET_SEGV_MTESERR  9  /* Synchronous ARM MTE exception */
 
 #define TARGET_ARCH_HAS_SETUP_FRAME
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
+
 #endif /* AARCH64_TARGET_SIGNAL_H */

linux-user/alpha/signal.c

@@ -55,13 +55,11 @@ struct target_ucontext {
 
 struct target_sigframe {
     struct target_sigcontext sc;
-    unsigned int retcode[3];
 };
 
 struct target_rt_sigframe {
     target_siginfo_t info;
     struct target_ucontext uc;
-    unsigned int retcode[3];
 };
 
 #define INSN_MOV_R30_R16        0x47fe0410
@@ -142,12 +140,7 @@ void setup_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         r26 = ka->ka_restorer;
     } else {
-        __put_user(INSN_MOV_R30_R16, &frame->retcode[0]);
-        __put_user(INSN_LDI_R0 + TARGET_NR_sigreturn,
-                   &frame->retcode[1]);
-        __put_user(INSN_CALLSYS, &frame->retcode[2]);
-        /* imb() */
-        r26 = frame_addr + offsetof(struct target_sigframe, retcode);
+        r26 = default_sigreturn;
     }
 
     unlock_user_struct(frame, frame_addr, 1);
@@ -196,12 +189,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka,
     if (ka->ka_restorer) {
         r26 = ka->ka_restorer;
     } else {
-        __put_user(INSN_MOV_R30_R16, &frame->retcode[0]);
-        __put_user(INSN_LDI_R0 + TARGET_NR_rt_sigreturn,
-                   &frame->retcode[1]);
-        __put_user(INSN_CALLSYS, &frame->retcode[2]);
-        /* imb(); */
-        r26 = frame_addr + offsetof(struct target_rt_sigframe, retcode);
+        r26 = default_rt_sigreturn;
     }
 
     if (err) {
@@ -269,3 +257,21 @@ long do_rt_sigreturn(CPUAlphaState *env)
     force_sig(TARGET_SIGSEGV);
     return -TARGET_QEMU_ESIGRETURN;
 }
+
+void setup_sigtramp(abi_ulong sigtramp_page)
+{
+    uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, 6 * 4, 0);
+    assert(tramp != NULL);
+
+    default_sigreturn = sigtramp_page;
+    __put_user(INSN_MOV_R30_R16, &tramp[0]);
+    __put_user(INSN_LDI_R0 + TARGET_NR_sigreturn, &tramp[1]);
+    __put_user(INSN_CALLSYS, &tramp[2]);
+
+    default_rt_sigreturn = sigtramp_page + 3 * 4;
+    __put_user(INSN_MOV_R30_R16, &tramp[3]);
+    __put_user(INSN_LDI_R0 + TARGET_NR_rt_sigreturn, &tramp[4]);
+    __put_user(INSN_CALLSYS, &tramp[5]);
+
+    unlock_user(tramp, sigtramp_page, 6 * 4);
+}

linux-user/alpha/target_signal.h

@@ -93,6 +93,7 @@ typedef struct target_sigaltstack {
 
 #define TARGET_ARCH_HAS_SETUP_FRAME
 #define TARGET_ARCH_HAS_KA_RESTORER
+#define TARGET_ARCH_HAS_SIGTRAMP_PAGE 1
 
 /* bit-flags */
 #define TARGET_SS_AUTODISARM (1U << 31) /* disable sas during sighandling */