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authorPeter Maydell <peter.maydell@linaro.org>2021-02-11 19:57:50 +0000
committerPeter Maydell <peter.maydell@linaro.org>2021-02-11 19:57:50 +0000
commiteac92d316351b855ba79eb374dd21cc367f1f9c1 (patch)
tree3dd45330cd46e965e5ac5dfff8379a55df7d497f /accel/tcg/cpu-exec.c
parentc973f06521b07af0f82893b75a1d55562fffb4b5 (diff)
parentd3c1183ffeb71ca3a783eae3d7e1c51e71e8a621 (diff)
downloadfocaccia-qemu-eac92d316351b855ba79eb374dd21cc367f1f9c1.tar.gz
focaccia-qemu-eac92d316351b855ba79eb374dd21cc367f1f9c1.zip
Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20210211-1' into staging
target-arm queue:
 * Correctly initialize MDCR_EL2.HPMN
 * versal: Use nr_apu_cpus in favor of hard coding 2
 * accel/tcg: Add URL of clang bug to comment about our workaround
 * Add support for FEAT_DIT, Data Independent Timing
 * Remove GPIO from unimplemented NPCM7XX
 * Fix SCR RES1 handling
 * Don't migrate CPUARMState.features

# gpg: Signature made Thu 11 Feb 2021 19:56:40 GMT
# gpg:                using RSA key E1A5C593CD419DE28E8315CF3C2525ED14360CDE
# gpg:                issuer "peter.maydell@linaro.org"
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@gmail.com>" [ultimate]
# gpg:                 aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>" [ultimate]
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83  15CF 3C25 25ED 1436 0CDE

* remotes/pmaydell/tags/pull-target-arm-20210211-1:
  target/arm: Correctly initialize MDCR_EL2.HPMN
  hw/arm: versal: Use nr_apu_cpus in favor of hard coding 2
  accel/tcg: Add URL of clang bug to comment about our workaround
  arm: Update infocenter.arm.com URLs
  target/arm: Set ID_PFR0.DIT to 1 for "max" 32-bit CPU
  target/arm: Set ID_AA64PFR0.DIT and ID_PFR0.DIT to 1 for "max" AA64 CPU
  target/arm: Support AA32 DIT by moving PSTATE_SS from cpsr into env->pstate
  target/arm: Add support for FEAT_DIT, Data Independent Timing
  hw/arm: Remove GPIO from unimplemented NPCM7XX
  target/arm: Fix SCR RES1 handling
  target/arm: Don't migrate CPUARMState.features

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'accel/tcg/cpu-exec.c')
-rw-r--r--accel/tcg/cpu-exec.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index d9ef69121c..f2819eec7d 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -773,17 +773,30 @@ int cpu_exec(CPUState *cpu)
     /* prepare setjmp context for exception handling */
     if (sigsetjmp(cpu->jmp_env, 0) != 0) {
 #if defined(__clang__)
-        /* Some compilers wrongly smash all local variables after
-         * siglongjmp. There were bug reports for gcc 4.5.0 and clang.
+        /*
+         * Some compilers wrongly smash all local variables after
+         * siglongjmp (the spec requires that only non-volatile locals
+         * which are changed between the sigsetjmp and siglongjmp are
+         * permitted to be trashed). There were bug reports for gcc
+         * 4.5.0 and clang.  The bug is fixed in all versions of gcc
+         * that we support, but is still unfixed in clang:
+         *   https://bugs.llvm.org/show_bug.cgi?id=21183
+         *
          * Reload essential local variables here for those compilers.
-         * Newer versions of gcc would complain about this code (-Wclobbered). */
+         * Newer versions of gcc would complain about this code (-Wclobbered),
+         * so we only perform the workaround for clang.
+         */
         cpu = current_cpu;
         cc = CPU_GET_CLASS(cpu);
-#else /* buggy compiler */
-        /* Assert that the compiler does not smash local variables. */
+#else
+        /*
+         * Non-buggy compilers preserve these locals; assert that
+         * they have the correct value.
+         */
         g_assert(cpu == current_cpu);
         g_assert(cc == CPU_GET_CLASS(cpu));
-#endif /* buggy compiler */
+#endif
+
 #ifndef CONFIG_SOFTMMU
         tcg_debug_assert(!have_mmap_lock());
 #endif