Handle CPU interrupts by inline checking of a flag

Fix some of the nasty TCG race conditions and crashes by implementing
cpu_exit() as setting a flag which is checked at the start of each TB.
This avoids crashes if a thread or signal handler calls cpu_exit()
while the execution thread is itself modifying the TB graph (which
may happen in system emulation mode as well as in linux-user mode
with a multithreaded guest binary).

This fixes the crashes seen in LP:668799; however there are another
class of crashes described in LP:1098729 which stem from the fact
that in linux-user with a multithreaded guest all threads will
use and modify the same global TCG date structures (including the
generated code buffer) without any kind of locking. This means that
multithreaded guest binaries are still in the "unsupported"
category.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
6 files changed
tree: cedcd8fd2c8b23401ca4275ce65388e745cbcb37
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. default-configs/
  6. disas/
  7. docs/
  8. fpu/
  9. fsdev/
  10. gdb-xml/
  11. hw/
  12. include/
  13. ldscripts/
  14. libcacard/
  15. linux-headers/
  16. linux-user/
  17. net/
  18. pc-bios/
  19. po/
  20. qapi/
  21. qga/
  22. QMP/
  23. qobject/
  24. qom/
  25. roms/
  26. scripts/
  27. slirp/
  28. stubs/
  29. sysconfigs/
  30. target-alpha/
  31. target-arm/
  32. target-cris/
  33. target-i386/
  34. target-lm32/
  35. target-m68k/
  36. target-microblaze/
  37. target-mips/
  38. target-openrisc/
  39. target-ppc/
  40. target-s390x/
  41. target-sh4/
  42. target-sparc/
  43. target-unicore32/
  44. target-xtensa/
  45. tcg/
  46. tests/
  47. trace/
  48. ui/
  49. util/
  50. .exrc
  51. .gitignore
  52. .gitmodules
  53. .mailmap
  54. aio-posix.c
  55. aio-win32.c
  56. arch_init.c
  57. async.c
  58. balloon.c
  59. block-migration.c
  60. block.c
  61. blockdev-nbd.c
  62. blockdev.c
  63. blockjob.c
  64. bt-host.c
  65. bt-vhci.c
  66. Changelog
  67. cmd.c
  68. cmd.h
  69. CODING_STYLE
  70. configure
  71. COPYING
  72. COPYING.LIB
  73. coroutine-gthread.c
  74. coroutine-sigaltstack.c
  75. coroutine-ucontext.c
  76. coroutine-win32.c
  77. cpu-exec.c
  78. cpus.c
  79. cputlb.c
  80. device_tree.c
  81. disas.c
  82. dma-helpers.c
  83. dump-stub.c
  84. dump.c
  85. exec.c
  86. gdbstub.c
  87. HACKING
  88. hmp-commands.hx
  89. hmp.c
  90. hmp.h
  91. iohandler.c
  92. ioport.c
  93. kvm-all.c
  94. kvm-stub.c
  95. LICENSE
  96. main-loop.c
  97. MAINTAINERS
  98. Makefile
  99. Makefile.objs
  100. Makefile.target
  101. memory.c
  102. memory_mapping-stub.c
  103. memory_mapping.c
  104. migration-exec.c
  105. migration-fd.c
  106. migration-tcp.c
  107. migration-unix.c
  108. migration.c
  109. monitor.c
  110. nbd.c
  111. os-posix.c
  112. os-win32.c
  113. page_cache.c
  114. qapi-schema-test.json
  115. qapi-schema.json
  116. qdict-test-data.txt
  117. qemu-bridge-helper.c
  118. qemu-char.c
  119. qemu-coroutine-io.c
  120. qemu-coroutine-lock.c
  121. qemu-coroutine-sleep.c
  122. qemu-coroutine.c
  123. qemu-doc.texi
  124. qemu-img-cmds.hx
  125. qemu-img.c
  126. qemu-img.texi
  127. qemu-io.c
  128. qemu-log.c
  129. qemu-nbd.c
  130. qemu-nbd.texi
  131. qemu-options-wrapper.h
  132. qemu-options.h
  133. qemu-options.hx
  134. qemu-seccomp.c
  135. qemu-tech.texi
  136. qemu-timer.c
  137. qemu.sasl
  138. qmp-commands.hx
  139. qmp.c
  140. qtest.c
  141. readline.c
  142. README
  143. rules.mak
  144. savevm.c
  145. spice-qemu-char.c
  146. tcg-runtime.c
  147. tci.c
  148. thread-pool.c
  149. thunk.c
  150. trace-events
  151. translate-all.c
  152. translate-all.h
  153. user-exec.c
  154. VERSION
  155. version.rc
  156. vl.c
  157. xbzrle.c
  158. xen-all.c
  159. xen-mapcache.c
  160. xen-stub.c