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| author | H.J. Lu <hongjiu.lu@intel.com> | 2018-07-04 03:01:33 +0000 |
|---|---|---|
| committer | H.J. Lu <hjl@gcc.gnu.org> | 2018-07-03 20:01:33 -0700 |
| commit | ebaa4deaf9f3bec32443e60fe74fce14686b4706 (patch) | |
| tree | fb0135f43e72e4ffd528ad5806930aa0f186f804 /gcc/config | |
| parent | 7422f0ff39697b53ad599834647c56cb0cb3c3a3 (diff) | |
| download | gcc-ebaa4deaf9f3bec32443e60fe74fce14686b4706.zip gcc-ebaa4deaf9f3bec32443e60fe74fce14686b4706.tar.gz gcc-ebaa4deaf9f3bec32443e60fe74fce14686b4706.tar.bz2 | |
i386: Add indirect_return function attribute
On x86, swapcontext may return via indirect branch when shadow stack
is enabled. To support code instrumentation of control-flow transfers
with -fcf-protection, add indirect_return function attribute to inform
compiler that a function may return via indirect branch.
Note: Unlike setjmp, swapcontext only returns once. Mark it return
twice will unnecessarily disable compiler optimization as shown in
the testcase here.
gcc/
PR target/85620
* config/i386/i386.c (rest_of_insert_endbranch): Also generate
ENDBRANCH for non-tail call which may return via indirect branch.
* doc/extend.texi: Document indirect_return attribute.
gcc/testsuite/
PR target/85620
* gcc.target/i386/pr85620-1.c: New test.
* gcc.target/i386/pr85620-2.c: Likewise.
* gcc.target/i386/pr85620-3.c: Likewise.
* gcc.target/i386/pr85620-4.c: Likewise.
From-SVN: r262370
Diffstat (limited to 'gcc/config')
| -rw-r--r-- | gcc/config/i386/i386.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index e6d1763..41461d5 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -2621,7 +2621,26 @@ rest_of_insert_endbranch (void) { if (CALL_P (insn)) { - if (find_reg_note (insn, REG_SETJMP, NULL) == NULL) + bool need_endbr; + need_endbr = find_reg_note (insn, REG_SETJMP, NULL) != NULL; + if (!need_endbr && !SIBLING_CALL_P (insn)) + { + rtx call = get_call_rtx_from (insn); + rtx fnaddr = XEXP (call, 0); + + /* Also generate ENDBRANCH for non-tail call which + may return via indirect branch. */ + if (MEM_P (fnaddr) + && GET_CODE (XEXP (fnaddr, 0)) == SYMBOL_REF) + { + tree fndecl = SYMBOL_REF_DECL (XEXP (fnaddr, 0)); + if (fndecl + && lookup_attribute ("indirect_return", + DECL_ATTRIBUTES (fndecl))) + need_endbr = true; + } + } + if (!need_endbr) continue; /* Generate ENDBRANCH after CALL, which can return more than twice, setjmp-like functions. */ @@ -45897,6 +45916,8 @@ static const struct attribute_spec ix86_attribute_table[] = ix86_handle_fndecl_attribute, NULL }, { "function_return", 1, 1, true, false, false, false, ix86_handle_fndecl_attribute, NULL }, + { "indirect_return", 0, 0, true, false, false, false, + ix86_handle_fndecl_attribute, NULL }, /* End element. */ { NULL, 0, 0, false, false, false, false, NULL, NULL } |