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cmd/internal/obj/x86: align functions with trap instruction

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Align functions with 0xCC (INT $3) - breakpoint instruction,
instead of 0x00, which can disassemble into valid instruction.

Change-Id: Ieda191886efc4aacb86f58bea1169fd1b3b57636
Reviewed-on: https://go-review.googlesource.com/16102
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
Reviewed-by: Gregory Shimansky <gregory.shimansky@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Ilya Tocar 2015-10-20 14:52:08 +03:00 committed by Keith Randall
parent 77b1fef27e
commit 7d2c6eb3f5
1 changed files with 10 additions and 1 deletions
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11
src/cmd/internal/obj/x86/asm6.go
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@ -1754,7 +1754,16 @@ func span6(ctxt *obj.Link, s *obj.LSym) {
c = naclpad(ctxt, s, c, -c&31)
}
c += -c & (FuncAlign - 1)
// Pad functions with trap instruction, to catch invalid jumps
if c&(FuncAlign-1) != 0 {
v = -c & (FuncAlign - 1)
obj.Symgrow(ctxt, s, int64(c)+int64(v))
for i := c; i < c+v; i++ {
// 0xCC is INT $3 - breakpoint instruction
s.P[i] = uint8(0xCC)
}
c += v
}
s.Size = int64(c)
if false { /* debug['a'] > 1 */