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Diffstat (limited to 'ANDROID_3.4.5/arch/arm/nwfpe/entry.S')
| -rw-r--r-- | ANDROID_3.4.5/arch/arm/nwfpe/entry.S | 124 |
1 files changed, 0 insertions, 124 deletions
diff --git a/ANDROID_3.4.5/arch/arm/nwfpe/entry.S b/ANDROID_3.4.5/arch/arm/nwfpe/entry.S deleted file mode 100644 index d18dde95..00000000 --- a/ANDROID_3.4.5/arch/arm/nwfpe/entry.S +++ /dev/null @@ -1,124 +0,0 @@ -/* - NetWinder Floating Point Emulator - (c) Rebel.COM, 1998 - (c) 1998, 1999 Philip Blundell - - Direct questions, comments to Scott Bambrough <scottb@netwinder.org> - - This program 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 2 of the License, or - (at your option) any later version. - - This program 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. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. -*/ - -#include <asm/opcodes.h> - -/* This is the kernel's entry point into the floating point emulator. -It is called from the kernel with code similar to this: - - sub r4, r5, #4 - ldrt r0, [r4] @ r0 = instruction - adrsvc al, r9, ret_from_exception @ r9 = normal FP return - adrsvc al, lr, fpundefinstr @ lr = undefined instr return - - get_current_task r10 - mov r8, #1 - strb r8, [r10, #TSK_USED_MATH] @ set current->used_math - add r10, r10, #TSS_FPESAVE @ r10 = workspace - ldr r4, .LC2 - ldr pc, [r4] @ Call FP emulator entry point - -The kernel expects the emulator to return via one of two possible -points of return it passes to the emulator. The emulator, if -successful in its emulation, jumps to ret_from_exception (passed in -r9) and the kernel takes care of returning control from the trap to -the user code. If the emulator is unable to emulate the instruction, -it returns via _fpundefinstr (passed via lr) and the kernel halts the -user program with a core dump. - -On entry to the emulator r10 points to an area of private FP workspace -reserved in the thread structure for this process. This is where the -emulator saves its registers across calls. The first word of this area -is used as a flag to detect the first time a process uses floating point, -so that the emulator startup cost can be avoided for tasks that don't -want it. - -This routine does three things: - -1) The kernel has created a struct pt_regs on the stack and saved the -user registers into it. See /usr/include/asm/proc/ptrace.h for details. - -2) It calls EmulateAll to emulate a floating point instruction. -EmulateAll returns 1 if the emulation was successful, or 0 if not. - -3) If an instruction has been emulated successfully, it looks ahead at -the next instruction. If it is a floating point instruction, it -executes the instruction, without returning to user space. In this -way it repeatedly looks ahead and executes floating point instructions -until it encounters a non floating point instruction, at which time it -returns via _fpreturn. - -This is done to reduce the effect of the trap overhead on each -floating point instructions. GCC attempts to group floating point -instructions to allow the emulator to spread the cost of the trap over -several floating point instructions. */ - -#include <asm/asm-offsets.h> - - .globl nwfpe_enter -nwfpe_enter: - mov r4, lr @ save the failure-return addresses - mov sl, sp @ we access the registers via 'sl' - - ldr r5, [sp, #S_PC] @ get contents of PC; - mov r6, r0 @ save the opcode -emulate: - ldr r1, [sp, #S_PSR] @ fetch the PSR - bl arm_check_condition @ check the condition - cmp r0, #ARM_OPCODE_CONDTEST_PASS @ condition passed? - - @ if condition code failed to match, next insn - bne next @ get the next instruction; - - mov r0, r6 @ prepare for EmulateAll() - bl EmulateAll @ emulate the instruction - cmp r0, #0 @ was emulation successful - moveq pc, r4 @ no, return failure - -next: -.Lx1: ldrt r6, [r5], #4 @ get the next instruction and - @ increment PC - - and r2, r6, #0x0F000000 @ test for FP insns - teq r2, #0x0C000000 - teqne r2, #0x0D000000 - teqne r2, #0x0E000000 - movne pc, r9 @ return ok if not a fp insn - - str r5, [sp, #S_PC] @ update PC copy in regs - - mov r0, r6 @ save a copy - b emulate @ check condition and emulate - - @ We need to be prepared for the instructions at .Lx1 and .Lx2 - @ to fault. Emit the appropriate exception gunk to fix things up. - @ ??? For some reason, faults can happen at .Lx2 even with a - @ plain LDR instruction. Weird, but it seems harmless. - .pushsection .fixup,"ax" - .align 2 -.Lfix: mov pc, r9 @ let the user eat segfaults - .popsection - - .pushsection __ex_table,"a" - .align 3 - .long .Lx1, .Lfix - .popsection |