)]}'
{
  "commit": "54a015104136974262afa4b8ddd943ea70dec8a2",
  "tree": "713f0c1f4d0afe62e5c568a424e309f70388cf7f",
  "parents": [
    "783e391b7b5b273cd20856d8f6f4878da8ec31b3"
  ],
  "author": {
    "name": "Roland McGrath",
    "email": "roland@redhat.com",
    "time": "Thu Apr 10 15:37:38 2008 -0700"
  },
  "committer": {
    "name": "Linus Torvalds",
    "email": "torvalds@linux-foundation.org",
    "time": "Thu Apr 10 17:28:26 2008 -0700"
  },
  "message": "asmlinkage_protect replaces prevent_tail_call\n\nThe prevent_tail_call() macro works around the problem of the compiler\nclobbering argument words on the stack, which for asmlinkage functions\nis the caller\u0027s (user\u0027s) struct pt_regs.  The tail/sibling-call\noptimization is not the only way that the compiler can decide to use\nstack argument words as scratch space, which we have to prevent.\nOther optimizations can do it too.\n\nUntil we have new compiler support to make \"asmlinkage\" binding on the\ncompiler\u0027s own use of the stack argument frame, we have work around all\nthe manifestations of this issue that crop up.\n\nMore cases seem to be prevented by also keeping the incoming argument\nvariables live at the end of the function.  This makes their original\nstack slots attractive places to leave those variables, so the compiler\ntends not clobber them for something else.  It\u0027s still no guarantee, but\nit handles some observed cases that prevent_tail_call() did not.\n\nSigned-off-by: Roland McGrath \u003croland@redhat.com\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n",
  "tree_diff": [
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