Fix safe_syscall_base for sparc64.

Fix host signal handling for sparc64-linux.
 Speedups for jump cache and work list probing.
 Fix for exception replays.
 Raise guest SIGBUS for user-only misaligned accesses.
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Merge remote-tracking branch 'remotes/rth-gitlab/tags/pull-tcg-20220211' into staging

Fix safe_syscall_base for sparc64.
Fix host signal handling for sparc64-linux.
Speedups for jump cache and work list probing.
Fix for exception replays.
Raise guest SIGBUS for user-only misaligned accesses.

# gpg: Signature made Fri 11 Feb 2022 01:27:16 GMT
# gpg:                using RSA key 7A481E78868B4DB6A85A05C064DF38E8AF7E215F
# gpg:                issuer "richard.henderson@linaro.org"
# gpg: Good signature from "Richard Henderson <richard.henderson@linaro.org>" [full]
# Primary key fingerprint: 7A48 1E78 868B 4DB6 A85A  05C0 64DF 38E8 AF7E 215F

* remotes/rth-gitlab/tags/pull-tcg-20220211: (34 commits)
  tests/tcg/multiarch: Add sigbus.c
  tcg/sparc: Support unaligned access for user-only
  tcg/sparc: Add tcg_out_jmpl_const for better tail calls
  tcg/sparc: Use the constant pool for 64-bit constants
  tcg/sparc: Convert patch_reloc to return bool
  tcg/sparc: Improve code gen for shifted 32-bit constants
  tcg/sparc: Add scratch argument to tcg_out_movi_int
  tcg/sparc: Split out tcg_out_movi_imm32
  tcg/sparc: Use tcg_out_movi_imm13 in tcg_out_addsub2_i64
  tcg/mips: Support unaligned access for softmmu
  tcg/mips: Support unaligned access for user-only
  tcg/arm: Support raising sigbus for user-only
  tcg/arm: Reserve a register for guest_base
  tcg/arm: Support unaligned access for softmmu
  tcg/arm: Check alignment for ldrd and strd
  tcg/arm: Remove use_armv6_instructions
  tcg/arm: Remove use_armv5t_instructions
  tcg/arm: Drop support for armv4 and armv5 hosts
  tcg/loongarch64: Support raising sigbus for user-only
  tcg/tci: Support raising sigbus for user-only
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

tests/tcg/multiarch/sigbus.c

@@ -0,0 +1,68 @@
+#define _GNU_SOURCE 1
+
+#include <assert.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <endian.h>
+
+
+unsigned long long x = 0x8877665544332211ull;
+void * volatile p = (void *)&x + 1;
+
+void sigbus(int sig, siginfo_t *info, void *uc)
+{
+    assert(sig == SIGBUS);
+    assert(info->si_signo == SIGBUS);
+#ifdef BUS_ADRALN
+    assert(info->si_code == BUS_ADRALN);
+#endif
+    assert(info->si_addr == p);
+    exit(EXIT_SUCCESS);
+}
+
+int main()
+{
+    struct sigaction sa = {
+        .sa_sigaction = sigbus,
+        .sa_flags = SA_SIGINFO
+    };
+    int allow_fail = 0;
+    int tmp;
+
+    tmp = sigaction(SIGBUS, &sa, NULL);
+    assert(tmp == 0);
+
+    /*
+     * Select an operation that's likely to enforce alignment.
+     * On many guests that support unaligned accesses by default,
+     * this is often an atomic operation.
+     */
+#if defined(__aarch64__)
+    asm volatile("ldxr %w0,[%1]" : "=r"(tmp) : "r"(p) : "memory");
+#elif defined(__alpha__)
+    asm volatile("ldl_l %0,0(%1)" : "=r"(tmp) : "r"(p) : "memory");
+#elif defined(__arm__)
+    asm volatile("ldrex %0,[%1]" : "=r"(tmp) : "r"(p) : "memory");
+#elif defined(__powerpc__)
+    asm volatile("lwarx %0,0,%1" : "=r"(tmp) : "r"(p) : "memory");
+#elif defined(__riscv_atomic)
+    asm volatile("lr.w %0,(%1)" : "=r"(tmp) : "r"(p) : "memory");
+#else
+    /* No insn known to fault unaligned -- try for a straight load. */
+    allow_fail = 1;
+    tmp = *(volatile int *)p;
+#endif
+
+    assert(allow_fail);
+
+    /*
+     * We didn't see a signal.
+     * We might as well validate the unaligned load worked.
+     */
+    if (BYTE_ORDER == LITTLE_ENDIAN) {
+        assert(tmp == 0x55443322);
+    } else {
+        assert(tmp == 0x77665544);
+    }
+    return EXIT_SUCCESS;
+}