morestack.S: Correct CFI information to do proper returns throughout function.
* config/i386/morestack.S: Correct CFI information to do proper returns throughout function. In 32-bit mode, save %ebx so that it is restored on unwind. From-SVN: r180633
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Ian Lance Taylor
Ian Lance Taylor
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4356b75d98
commit
18b4bd7b6c
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@ -1,3 +1,9 @@
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2011-10-28 Ian Lance Taylor <iant@google.com>
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* config/i386/morestack.S: Correct CFI information to do proper
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returns throughout function. In 32-bit mode, save %ebx so that it
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is restored on unwind.
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2011-10-25 Bernd Schmidt <bernds@codesourcery.com>
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* config/c6x/pr-support.c (__gnu_unwind_24bit): Correct logic for the
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@ -139,44 +139,68 @@ __morestack:
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.cfi_lsda 0x1b,.LLSDA1
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#endif
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# Set up a normal backtrace.
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pushl %ebp
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.cfi_def_cfa_offset 8
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.cfi_offset %ebp, -8
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movl %esp, %ebp
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.cfi_def_cfa_register %ebp
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# We return below with a ret $8. We will return to a single
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# return instruction, which will return to the caller of our
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# caller. We let the unwinder skip that single return
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# instruction, and just return to the real caller.
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.cfi_offset 8, 8
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# Here CFA points just past the return address on the stack,
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# e.g., on function entry it is %esp + 4. Later we will
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# change it to %ebp + 8, as set by .cfi_def_cfa_register and
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# .cfi_def_cfa_offset above. The stack looks like this:
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# CFA + 12: stack pointer after two returns
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# CFA + 8: return address of morestack caller's caller
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# CFA + 4: size of parameters
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# CFA: new stack frame size
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# CFA - 4: return address of this function
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# CFA - 8: previous value of %ebp; %ebp points here
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# We want to set %esp to the stack pointer after the double
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# return, which is CFA + 12.
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.cfi_offset 8, 8 # New PC stored at CFA + 8
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.cfi_escape 0x15, 4, 0x7d # DW_CFA_val_offset_sf, %esp, 12/-4
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# i.e., next %esp is CFA + 12
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# Set up a normal backtrace.
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pushl %ebp
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.cfi_def_cfa_offset 8
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.cfi_offset %ebp, -8
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movl %esp,%ebp
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.cfi_def_cfa_register %ebp
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# In 32-bit mode the parameters are pushed on the stack. The
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# argument size is pushed then the new stack frame size is
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# pushed.
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# Align stack to 16-byte boundary with enough space for saving
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# registers and passing parameters to functions we call.
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subl $40,%esp
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# Because our cleanup code may need to clobber %ebx, we need
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# to save it here so the unwinder can restore the value used
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# by the caller. Note that we don't have to restore the
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# register, since we don't change it, we just have to save it
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# for the unwinder.
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movl %ebx,-4(%ebp)
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.cfi_offset %ebx, -12
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# In 32-bit mode the registers %eax, %edx, and %ecx may be
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# used for parameters, depending on the regparm and fastcall
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# attributes.
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pushl %eax
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pushl %edx
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pushl %ecx
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movl %eax,-8(%ebp)
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movl %edx,-12(%ebp)
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movl %ecx,-16(%ebp)
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call __morestack_block_signals
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pushl 12(%ebp) # The size of the parameters.
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movl 12(%ebp),%eax # The size of the parameters.
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movl %eax,8(%esp)
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leal 20(%ebp),%eax # Address of caller's parameters.
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pushl %eax
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movl %eax,4(%esp)
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addl $BACKOFF,8(%ebp) # Ask for backoff bytes.
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leal 8(%ebp),%eax # The address of the new frame size.
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pushl %eax
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movl %eax,(%esp)
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# Note that %esp is exactly 32 bytes below the CFA -- perfect for
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# a 16-byte aligned stack. That said, we still ought to compile
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# generic-morestack.c with -mpreferred-stack-boundary=2. FIXME.
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call __generic_morestack
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movl %eax,%esp # Switch to the new stack.
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@ -191,8 +215,8 @@ __morestack:
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call __morestack_unblock_signals
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movl -8(%ebp),%edx # Restore registers.
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movl -12(%ebp),%ecx
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movl -12(%ebp),%edx # Restore registers.
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movl -16(%ebp),%ecx
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movl 4(%ebp),%eax # Increment the return address
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cmpb $0xc3,(%eax) # to skip the ret instruction;
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@ -200,12 +224,12 @@ __morestack:
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addl $2,%eax
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1: inc %eax
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movl %eax,-8(%ebp) # Store return address in an
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movl %eax,-12(%ebp) # Store return address in an
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# unused slot.
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movl -4(%ebp),%eax # Restore the last register.
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movl -8(%ebp),%eax # Restore the last register.
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call *-8(%ebp) # Call our caller!
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call *-12(%ebp) # Call our caller!
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# The caller will return here, as predicted.
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@ -255,9 +279,13 @@ __morestack:
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popl %eax
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.cfi_remember_state
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# We never changed %ebx, so we don't have to actually restore it.
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.cfi_restore %ebx
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popl %ebp
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.cfi_restore %ebp
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.cfi_def_cfa %esp, 12
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.cfi_def_cfa %esp, 4
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ret $8 # Return to caller, which will
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# immediately return. Pop
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# arguments as we go.
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@ -300,13 +328,6 @@ __morestack:
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.cfi_lsda 0x1b,.LLSDA1
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#endif
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# Set up a normal backtrace.
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pushq %rbp
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.cfi_def_cfa_offset 16
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.cfi_offset %rbp, -16
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movq %rsp, %rbp
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.cfi_def_cfa_register %rbp
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# We will return a single return instruction, which will
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# return to the caller of our caller. Let the unwinder skip
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# that single return instruction, and just return to the real
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@ -314,6 +335,13 @@ __morestack:
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.cfi_offset 16, 0
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.cfi_escape 0x15, 7, 0x7f # DW_CFA_val_offset_sf, %esp, 8/-8
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# Set up a normal backtrace.
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pushq %rbp
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.cfi_def_cfa_offset 16
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.cfi_offset %rbp, -16
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movq %rsp, %rbp
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.cfi_def_cfa_register %rbp
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# In 64-bit mode the new stack frame size is passed in r10
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# and the argument size is passed in r11.
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