diff options
Diffstat (limited to 'libgcc/config/i386/morestack.S')
| -rw-r--r-- | libgcc/config/i386/morestack.S | 593 |
1 files changed, 593 insertions, 0 deletions
diff --git a/libgcc/config/i386/morestack.S b/libgcc/config/i386/morestack.S new file mode 100644 index 000000000..10fa1fdf7 --- /dev/null +++ b/libgcc/config/i386/morestack.S @@ -0,0 +1,593 @@ +# x86/x86_64 support for -fsplit-stack. +# Copyright (C) 2009, 2010 Free Software Foundation, Inc. +# Contributed by Ian Lance Taylor <iant@google.com>. + +# This file is part of GCC. + +# GCC is free software; you can redistribute it and/or modify it under +# the terms of the GNU General Public License as published by the Free +# Software Foundation; either version 3, or (at your option) any later +# version. + +# GCC is distributed in the hope that it will be useful, but WITHOUT ANY +# WARRANTY; without even the implied warranty of MERCHANTABILITY or +# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License +# for more details. + +# Under Section 7 of GPL version 3, you are granted additional +# permissions described in the GCC Runtime Library Exception, version +# 3.1, as published by the Free Software Foundation. + +# You should have received a copy of the GNU General Public License and +# a copy of the GCC Runtime Library Exception along with this program; +# see the files COPYING3 and COPYING.RUNTIME respectively. If not, see +# <http://www.gnu.org/licenses/>. + + +# Support for allocating more stack space when using -fsplit-stack. +# When a function discovers that it needs more stack space, it will +# call __morestack with the size of the stack frame and the size of +# the parameters to copy from the old stack frame to the new one. +# The __morestack function preserves the parameter registers and +# calls __generic_morestack to actually allocate the stack space. + +# When this is called stack space is very low, but we ensure that +# there is enough space to push the parameter registers and to call +# __generic_morestack. + +# When calling __generic_morestack, FRAME_SIZE points to the size of +# the desired frame when the function is called, and the function +# sets it to the size of the allocated stack. OLD_STACK points to +# the parameters on the old stack and PARAM_SIZE is the number of +# bytes of parameters to copy to the new stack. These are the +# parameters of the function that called __morestack. The +# __generic_morestack function returns the new stack pointer, +# pointing to the address of the first copied parameter. The return +# value minus the returned *FRAME_SIZE will be the first address on +# the stack which we should not use. + +# void *__generic_morestack (size_t *frame_size, void *old_stack, +# size_t param_size); + +# The __morestack routine has to arrange for the caller to return to a +# stub on the new stack. The stub is responsible for restoring the +# old stack pointer and returning to the caller's caller. This calls +# __generic_releasestack to retrieve the old stack pointer and release +# the newly allocated stack. + +# void *__generic_releasestack (size_t *available); + +# We do a little dance so that the processor's call/return return +# address prediction works out. The compiler arranges for the caller +# to look like this: +# call __generic_morestack +# ret +# L: +# // carry on with function +# After we allocate more stack, we call L, which is in our caller. +# When that returns (to the predicted instruction), we release the +# stack segment and reset the stack pointer. We then return to the +# predicted instruction, namely the ret instruction immediately after +# the call to __generic_morestack. That then returns to the caller of +# the original caller. + + +# The amount of extra space we ask for. In general this has to be +# enough for the dynamic loader to find a symbol and for a signal +# handler to run. + +#ifndef __x86_64__ +#define BACKOFF (1024) +#else +#define BACKOFF (1536) +#endif + + +# This entry point is for split-stack code which calls non-split-stack +# code. When the linker sees this case, it converts the call to +# __morestack to call __morestack_non_split instead. We just bump the +# requested stack space by 16K. + + .global __morestack_non_split + .hidden __morestack_non_split + +#ifdef __ELF__ + .type __morestack_non_split,@function +#endif + +__morestack_non_split: + +#ifndef __x86_64__ + addl $0x4000,4(%esp) +#else + addq $0x4000,%r10 +#endif + +#ifdef __ELF__ + .size __morestack_non_split, . - __morestack_non_split +#endif + +# __morestack_non_split falls through into __morestack. + + +# The __morestack function. + + .global __morestack + .hidden __morestack + +#ifdef __ELF__ + .type __morestack,@function +#endif + +__morestack: +.LFB1: + .cfi_startproc + + +#ifndef __x86_64__ + + +# The 32-bit __morestack function. + + # We use a cleanup to restore the stack guard if an exception + # is thrown through this code. +#ifndef __PIC__ + .cfi_personality 0,__gcc_personality_v0 + .cfi_lsda 0,.LLSDA1 +#else + .cfi_personality 0x9b,DW.ref.__gcc_personality_v0 + .cfi_lsda 0x1b,.LLSDA1 +#endif + + # Set up a normal backtrace. + pushl %ebp + .cfi_def_cfa_offset 8 + .cfi_offset %ebp, -8 + movl %esp, %ebp + .cfi_def_cfa_register %ebp + + # We return below with a ret $8. We will return to a single + # return instruction, which will return to the caller of our + # caller. We let the unwinder skip that single return + # instruction, and just return to the real caller. + .cfi_offset 8, 8 + .cfi_escape 0x15, 4, 0x7d # DW_CFA_val_offset_sf, %esp, 12/-4 + + # In 32-bit mode the parameters are pushed on the stack. The + # argument size is pushed then the new stack frame size is + # pushed. + + # In 32-bit mode the registers %eax, %edx, and %ecx may be + # used for parameters, depending on the regparm and fastcall + # attributes. + + pushl %eax + pushl %edx + pushl %ecx + + call __morestack_block_signals + + pushl 12(%ebp) # The size of the parameters. + leal 20(%ebp),%eax # Address of caller's parameters. + pushl %eax + addl $BACKOFF,8(%ebp) # Ask for backoff bytes. + leal 8(%ebp),%eax # The address of the new frame size. + pushl %eax + + # Note that %esp is exactly 32 bytes below the CFA -- perfect for + # a 16-byte aligned stack. That said, we still ought to compile + # generic-morestack.c with -mpreferred-stack-boundary=2. FIXME. + call __generic_morestack + + movl %eax,%esp # Switch to the new stack. + subl 8(%ebp),%eax # The end of the stack space. + addl $BACKOFF,%eax # Back off 512 bytes. + +.LEHB0: + # FIXME: The offset must match + # TARGET_THREAD_SPLIT_STACK_OFFSET in + # gcc/config/i386/linux.h. + movl %eax,%gs:0x30 # Save the new stack boundary. + + call __morestack_unblock_signals + + movl -8(%ebp),%edx # Restore registers. + movl -12(%ebp),%ecx + + movl 4(%ebp),%eax # Increment the return address + cmpb $0xc3,(%eax) # to skip the ret instruction; + je 1f # see above. + addl $2,%eax +1: inc %eax + + movl %eax,-8(%ebp) # Store return address in an + # unused slot. + + movl -4(%ebp),%eax # Restore the last register. + + call *-8(%ebp) # Call our caller! + + # The caller will return here, as predicted. + + # Save the registers which may hold a return value. We + # assume that __generic_releasestack does not touch any + # floating point or vector registers. + pushl %eax + pushl %edx + + # Push the arguments to __generic_releasestack now so that the + # stack is at a 16-byte boundary for + # __morestack_block_signals. + pushl $0 # Where the available space is returned. + leal 0(%esp),%eax # Push its address. + push %eax + + call __morestack_block_signals + + call __generic_releasestack + + subl 4(%esp),%eax # Subtract available space. + addl $BACKOFF,%eax # Back off 512 bytes. +.LEHE0: + movl %eax,%gs:0x30 # Save the new stack boundary. + + addl $8,%esp # Remove values from stack. + + # We need to restore the old stack pointer, which is in %rbp, + # before we unblock signals. We also need to restore %eax and + # %edx after we unblock signals but before we return. Do this + # by moving %eax and %edx from the current stack to the old + # stack. + + popl %edx # Pop return value from current stack. + popl %eax + + movl %ebp,%esp # Restore stack pointer. + + pushl %eax # Push return value on old stack. + pushl %edx + subl $8,%esp # Align stack to 16-byte boundary. + + call __morestack_unblock_signals + + addl $8,%esp + popl %edx # Restore return value. + popl %eax + + .cfi_remember_state + popl %ebp + .cfi_restore %ebp + .cfi_def_cfa %esp, 12 + ret $8 # Return to caller, which will + # immediately return. Pop + # arguments as we go. + +# This is the cleanup code called by the stack unwinder when unwinding +# through the code between .LEHB0 and .LEHE0 above. + +.L1: + .cfi_restore_state + subl $16,%esp # Maintain 16 byte alignment. + movl %eax,4(%esp) # Save exception header. + movl %ebp,(%esp) # Stack pointer after resume. + call __generic_findstack + movl %ebp,%ecx # Get the stack pointer. + subl %eax,%ecx # Subtract available space. + addl $BACKOFF,%ecx # Back off 512 bytes. + movl %ecx,%gs:0x30 # Save new stack boundary. + movl 4(%esp),%eax # Function argument. + movl %eax,(%esp) +#ifdef __PIC__ +#undef __i686 + call __i686.get_pc_thunk.bx # %ebx may not be set up for us. + addl $_GLOBAL_OFFSET_TABLE_, %ebx + call _Unwind_Resume@PLT # Resume unwinding. +#else + call _Unwind_Resume +#endif + +#else /* defined(__x86_64__) */ + + +# The 64-bit __morestack function. + + # We use a cleanup to restore the stack guard if an exception + # is thrown through this code. +#ifndef __PIC__ + .cfi_personality 0x3,__gcc_personality_v0 + .cfi_lsda 0x3,.LLSDA1 +#else + .cfi_personality 0x9b,DW.ref.__gcc_personality_v0 + .cfi_lsda 0x1b,.LLSDA1 +#endif + + # Set up a normal backtrace. + pushq %rbp + .cfi_def_cfa_offset 16 + .cfi_offset %rbp, -16 + movq %rsp, %rbp + .cfi_def_cfa_register %rbp + + # We will return a single return instruction, which will + # return to the caller of our caller. Let the unwinder skip + # that single return instruction, and just return to the real + # caller. + .cfi_offset 16, 0 + .cfi_escape 0x15, 7, 0x7f # DW_CFA_val_offset_sf, %esp, 8/-8 + + # In 64-bit mode the new stack frame size is passed in r10 + # and the argument size is passed in r11. + + addq $BACKOFF,%r10 # Ask for backoff bytes. + pushq %r10 # Save new frame size. + + # In 64-bit mode the registers %rdi, %rsi, %rdx, %rcx, %r8, + # and %r9 may be used for parameters. We also preserve %rax + # which the caller may use to hold %r10. + + pushq %rax + pushq %rdi + pushq %rsi + pushq %rdx + pushq %rcx + pushq %r8 + pushq %r9 + + pushq %r11 + pushq $0 # For alignment. + + call __morestack_block_signals + + leaq -8(%rbp),%rdi # Address of new frame size. + leaq 24(%rbp),%rsi # The caller's parameters. + addq $8,%rsp + popq %rdx # The size of the parameters. + + call __generic_morestack + + movq -8(%rbp),%r10 # Reload modified frame size + movq %rax,%rsp # Switch to the new stack. + subq %r10,%rax # The end of the stack space. + addq $BACKOFF,%rax # Back off 1024 bytes. + +.LEHB0: + # FIXME: The offset must match + # TARGET_THREAD_SPLIT_STACK_OFFSET in + # gcc/config/i386/linux64.h. + movq %rax,%fs:0x70 # Save the new stack boundary. + + call __morestack_unblock_signals + + movq -24(%rbp),%rdi # Restore registers. + movq -32(%rbp),%rsi + movq -40(%rbp),%rdx + movq -48(%rbp),%rcx + movq -56(%rbp),%r8 + movq -64(%rbp),%r9 + + movq 8(%rbp),%r10 # Increment the return address + incq %r10 # to skip the ret instruction; + # see above. + + movq -16(%rbp),%rax # Restore caller's %rax. + + call *%r10 # Call our caller! + + # The caller will return here, as predicted. + + # Save the registers which may hold a return value. We + # assume that __generic_releasestack does not touch any + # floating point or vector registers. + pushq %rax + pushq %rdx + + call __morestack_block_signals + + pushq $0 # For alignment. + pushq $0 # Where the available space is returned. + leaq 0(%rsp),%rdi # Pass its address. + + call __generic_releasestack + + subq 0(%rsp),%rax # Subtract available space. + addq $BACKOFF,%rax # Back off 1024 bytes. +.LEHE0: + movq %rax,%fs:0x70 # Save the new stack boundary. + + addq $16,%rsp # Remove values from stack. + + # We need to restore the old stack pointer, which is in %rbp, + # before we unblock signals. We also need to restore %rax and + # %rdx after we unblock signals but before we return. Do this + # by moving %rax and %rdx from the current stack to the old + # stack. + + popq %rdx # Pop return value from current stack. + popq %rax + + movq %rbp,%rsp # Restore stack pointer. + + pushq %rax # Push return value on old stack. + pushq %rdx + + call __morestack_unblock_signals + + popq %rdx # Restore return value. + popq %rax + + .cfi_remember_state + popq %rbp + .cfi_restore %rbp + .cfi_def_cfa %rsp, 8 + ret # Return to caller, which will + # immediately return. + +# This is the cleanup code called by the stack unwinder when unwinding +# through the code between .LEHB0 and .LEHE0 above. + +.L1: + .cfi_restore_state + subq $16,%rsp # Maintain 16 byte alignment. + movq %rax,(%rsp) # Save exception header. + movq %rbp,%rdi # Stack pointer after resume. + call __generic_findstack + movq %rbp,%rcx # Get the stack pointer. + subq %rax,%rcx # Subtract available space. + addq $BACKOFF,%rcx # Back off 1024 bytes. + movq %rcx,%fs:0x70 # Save new stack boundary. + movq (%rsp),%rdi # Restore exception data for call. +#ifdef __PIC__ + call _Unwind_Resume@PLT # Resume unwinding. +#else + call _Unwind_Resume # Resume unwinding. +#endif + +#endif /* defined(__x86_64__) */ + + .cfi_endproc +#ifdef __ELF__ + .size __morestack, . - __morestack +#endif + + +# The exception table. This tells the personality routine to execute +# the exception handler. + + .section .gcc_except_table,"a",@progbits + .align 4 +.LLSDA1: + .byte 0xff # @LPStart format (omit) + .byte 0xff # @TType format (omit) + .byte 0x1 # call-site format (uleb128) + .uleb128 .LLSDACSE1-.LLSDACSB1 # Call-site table length +.LLSDACSB1: + .uleb128 .LEHB0-.LFB1 # region 0 start + .uleb128 .LEHE0-.LEHB0 # length + .uleb128 .L1-.LFB1 # landing pad + .uleb128 0 # action +.LLSDACSE1: + + + .global __gcc_personality_v0 +#ifdef __PIC__ + # Build a position independent reference to the basic + # personality function. + .hidden DW.ref.__gcc_personality_v0 + .weak DW.ref.__gcc_personality_v0 + .section .data.DW.ref.__gcc_personality_v0,"awG",@progbits,DW.ref.__gcc_personality_v0,comdat + .type DW.ref.__gcc_personality_v0, @object +DW.ref.__gcc_personality_v0: +#ifndef __x86_64 + .align 4 + .size DW.ref.__gcc_personality_v0, 4 + .long __gcc_personality_v0 +#else + .align 8 + .size DW.ref.__gcc_personality_v0, 8 + .quad __gcc_personality_v0 +#endif +#endif + +#ifdef __x86_64__ + +# This entry point is used for the large model. With this entry point +# the upper 32 bits of %r10 hold the argument size and the lower 32 +# bits hold the new stack frame size. There doesn't seem to be a way +# to know in the assembler code that we are assembling for the large +# model, and there doesn't seem to be a large model multilib anyhow. +# If one is developed, then the non-PIC code is probably OK since we +# will probably be close to the morestack code, but the PIC code +# almost certainly needs to be changed. FIXME. + + .text + .global __morestack_large_model + .hidden __morestack_large_model + +#ifdef __ELF__ + .type __morestack_large_model,@function +#endif + +__morestack_large_model: + + .cfi_startproc + + movq %r10, %r11 + andl $0xffffffff, %r10d + sarq $32, %r11 + jmp __morestack + + .cfi_endproc +#ifdef __ELF__ + .size __morestack_large_model, . - __morestack_large_model +#endif + +#endif /* __x86_64__ */ + +# Initialize the stack test value when the program starts or when a +# new thread starts. We don't know how large the main stack is, so we +# guess conservatively. We might be able to use getrlimit here. + + .text + .global __stack_split_initialize + .hidden __stack_split_initialize + +#ifdef __ELF__ + .type __stack_split_initialize, @function +#endif + +__stack_split_initialize: + +#ifndef __x86_64__ + + leal -16000(%esp),%eax # We should have at least 16K. + movl %eax,%gs:0x30 + pushl $16000 + pushl %esp +#ifdef __PIC__ + call __generic_morestack_set_initial_sp@PLT +#else + call __generic_morestack_set_initial_sp +#endif + addl $8,%esp + ret + +#else /* defined(__x86_64__) */ + + leaq -16000(%rsp),%rax # We should have at least 16K. + movq %rax,%fs:0x70 + movq %rsp,%rdi + movq $16000,%rsi +#ifdef __PIC__ + call __generic_morestack_set_initial_sp@PLT +#else + call __generic_morestack_set_initial_sp +#endif + ret + +#endif /* defined(__x86_64__) */ + +#ifdef __ELF__ + .size __stack_split_initialize, . - __stack_split_initialize +#endif + + +# Make __stack_split_initialize a high priority constructor. FIXME: +# This is ELF specific. + + .section .ctors.65535,"aw",@progbits + +#ifndef __x86_64__ + .align 4 + .long __stack_split_initialize + .long __morestack_load_mmap +#else + .align 8 + .quad __stack_split_initialize + .quad __morestack_load_mmap +#endif + +#ifdef __ELF__ + .section .note.GNU-stack,"",@progbits + .section .note.GNU-split-stack,"",@progbits + .section .note.GNU-no-split-stack,"",@progbits +#endif |