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bd6be579a7
Functions in math-emu are annotated as ENTRY() symbols, but their
ends are not annotated at all. But these are standard functions
called from C, with proper stack register update etc.
Omitting the ends means:
* the annotations are not paired and we cannot deal with such functions
e.g. in objtool
* the symbols are not marked as functions in the object file
* there are no sizes of the functions in the object file
So fix this by adding ENDPROC() to each such case in math-emu.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170824080624.7768-1-jslaby@suse.cz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
711 lines
18 KiB
ArmAsm
711 lines
18 KiB
ArmAsm
.file "reg_round.S"
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/*---------------------------------------------------------------------------+
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| reg_round.S |
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| |
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| Rounding/truncation/etc for FPU basic arithmetic functions. |
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| |
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| Copyright (C) 1993,1995,1997 |
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| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
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| Australia. E-mail billm@suburbia.net |
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| |
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| This code has four possible entry points. |
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| The following must be entered by a jmp instruction: |
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| fpu_reg_round, fpu_reg_round_sqrt, and fpu_Arith_exit. |
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| |
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| The FPU_round entry point is intended to be used by C code. |
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| From C, call as: |
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| int FPU_round(FPU_REG *arg, unsigned int extent, unsigned int control_w) |
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| |
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| Return value is the tag of the answer, or-ed with FPU_Exception if |
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| one was raised, or -1 on internal error. |
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| |
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| For correct "up" and "down" rounding, the argument must have the correct |
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| sign. |
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+---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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| Four entry points. |
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| |
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| Needed by both the fpu_reg_round and fpu_reg_round_sqrt entry points: |
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| %eax:%ebx 64 bit significand |
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| %edx 32 bit extension of the significand |
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| %edi pointer to an FPU_REG for the result to be stored |
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| stack calling function must have set up a C stack frame and |
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| pushed %esi, %edi, and %ebx |
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| |
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| Needed just for the fpu_reg_round_sqrt entry point: |
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| %cx A control word in the same format as the FPU control word. |
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| Otherwise, PARAM4 must give such a value. |
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| |
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| The significand and its extension are assumed to be exact in the |
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| following sense: |
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| If the significand by itself is the exact result then the significand |
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| extension (%edx) must contain 0, otherwise the significand extension |
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| must be non-zero. |
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| If the significand extension is non-zero then the significand is |
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| smaller than the magnitude of the correct exact result by an amount |
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| greater than zero and less than one ls bit of the significand. |
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| The significand extension is only required to have three possible |
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| non-zero values: |
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| less than 0x80000000 <=> the significand is less than 1/2 an ls |
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| bit smaller than the magnitude of the |
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| true exact result. |
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| exactly 0x80000000 <=> the significand is exactly 1/2 an ls bit |
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| smaller than the magnitude of the true |
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| exact result. |
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| greater than 0x80000000 <=> the significand is more than 1/2 an ls |
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| bit smaller than the magnitude of the |
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| true exact result. |
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| |
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+---------------------------------------------------------------------------*/
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/*---------------------------------------------------------------------------+
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| The code in this module has become quite complex, but it should handle |
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| all of the FPU flags which are set at this stage of the basic arithmetic |
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| computations. |
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| There are a few rare cases where the results are not set identically to |
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| a real FPU. These require a bit more thought because at this stage the |
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| results of the code here appear to be more consistent... |
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| This may be changed in a future version. |
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+---------------------------------------------------------------------------*/
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#include "fpu_emu.h"
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#include "exception.h"
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#include "control_w.h"
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/* Flags for FPU_bits_lost */
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#define LOST_DOWN $1
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#define LOST_UP $2
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/* Flags for FPU_denormal */
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#define DENORMAL $1
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#define UNMASKED_UNDERFLOW $2
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#ifndef NON_REENTRANT_FPU
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/* Make the code re-entrant by putting
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local storage on the stack: */
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#define FPU_bits_lost (%esp)
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#define FPU_denormal 1(%esp)
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#else
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/* Not re-entrant, so we can gain speed by putting
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local storage in a static area: */
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.data
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.align 4,0
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FPU_bits_lost:
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.byte 0
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FPU_denormal:
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.byte 0
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#endif /* NON_REENTRANT_FPU */
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.text
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.globl fpu_reg_round
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.globl fpu_Arith_exit
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/* Entry point when called from C */
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ENTRY(FPU_round)
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pushl %ebp
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movl %esp,%ebp
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pushl %esi
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pushl %edi
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pushl %ebx
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movl PARAM1,%edi
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movl SIGH(%edi),%eax
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movl SIGL(%edi),%ebx
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movl PARAM2,%edx
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fpu_reg_round: /* Normal entry point */
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movl PARAM4,%ecx
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#ifndef NON_REENTRANT_FPU
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pushl %ebx /* adjust the stack pointer */
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#endif /* NON_REENTRANT_FPU */
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#ifdef PARANOID
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/* Cannot use this here yet */
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/* orl %eax,%eax */
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/* jns L_entry_bugged */
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#endif /* PARANOID */
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cmpw EXP_UNDER,EXP(%edi)
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jle L_Make_denorm /* The number is a de-normal */
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movb $0,FPU_denormal /* 0 -> not a de-normal */
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Denorm_done:
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movb $0,FPU_bits_lost /* No bits yet lost in rounding */
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movl %ecx,%esi
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andl CW_PC,%ecx
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cmpl PR_64_BITS,%ecx
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je LRound_To_64
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cmpl PR_53_BITS,%ecx
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je LRound_To_53
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cmpl PR_24_BITS,%ecx
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je LRound_To_24
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#ifdef PECULIAR_486
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/* With the precision control bits set to 01 "(reserved)", a real 80486
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behaves as if the precision control bits were set to 11 "64 bits" */
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cmpl PR_RESERVED_BITS,%ecx
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je LRound_To_64
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#ifdef PARANOID
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jmp L_bugged_denorm_486
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#endif /* PARANOID */
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#else
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#ifdef PARANOID
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jmp L_bugged_denorm /* There is no bug, just a bad control word */
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#endif /* PARANOID */
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#endif /* PECULIAR_486 */
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/* Round etc to 24 bit precision */
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LRound_To_24:
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movl %esi,%ecx
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andl CW_RC,%ecx
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cmpl RC_RND,%ecx
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je LRound_nearest_24
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cmpl RC_CHOP,%ecx
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je LCheck_truncate_24
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cmpl RC_UP,%ecx /* Towards +infinity */
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je LUp_24
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cmpl RC_DOWN,%ecx /* Towards -infinity */
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je LDown_24
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#ifdef PARANOID
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jmp L_bugged_round24
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#endif /* PARANOID */
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LUp_24:
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cmpb SIGN_POS,PARAM5
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jne LCheck_truncate_24 /* If negative then up==truncate */
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jmp LCheck_24_round_up
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LDown_24:
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cmpb SIGN_POS,PARAM5
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je LCheck_truncate_24 /* If positive then down==truncate */
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LCheck_24_round_up:
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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orl %ebx,%ecx
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orl %edx,%ecx
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jnz LDo_24_round_up
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jmp L_Re_normalise
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LRound_nearest_24:
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/* Do rounding of the 24th bit if needed (nearest or even) */
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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cmpl $0x00000080,%ecx
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jc LCheck_truncate_24 /* less than half, no increment needed */
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jne LGreater_Half_24 /* greater than half, increment needed */
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/* Possibly half, we need to check the ls bits */
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orl %ebx,%ebx
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jnz LGreater_Half_24 /* greater than half, increment needed */
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orl %edx,%edx
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jnz LGreater_Half_24 /* greater than half, increment needed */
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/* Exactly half, increment only if 24th bit is 1 (round to even) */
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testl $0x00000100,%eax
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jz LDo_truncate_24
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LGreater_Half_24: /* Rounding: increment at the 24th bit */
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LDo_24_round_up:
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andl $0xffffff00,%eax /* Truncate to 24 bits */
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xorl %ebx,%ebx
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movb LOST_UP,FPU_bits_lost
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addl $0x00000100,%eax
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jmp LCheck_Round_Overflow
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LCheck_truncate_24:
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movl %eax,%ecx
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andl $0x000000ff,%ecx
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orl %ebx,%ecx
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orl %edx,%ecx
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jz L_Re_normalise /* No truncation needed */
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LDo_truncate_24:
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andl $0xffffff00,%eax /* Truncate to 24 bits */
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xorl %ebx,%ebx
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movb LOST_DOWN,FPU_bits_lost
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jmp L_Re_normalise
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/* Round etc to 53 bit precision */
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LRound_To_53:
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movl %esi,%ecx
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andl CW_RC,%ecx
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cmpl RC_RND,%ecx
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je LRound_nearest_53
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cmpl RC_CHOP,%ecx
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je LCheck_truncate_53
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cmpl RC_UP,%ecx /* Towards +infinity */
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je LUp_53
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cmpl RC_DOWN,%ecx /* Towards -infinity */
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je LDown_53
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#ifdef PARANOID
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jmp L_bugged_round53
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#endif /* PARANOID */
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LUp_53:
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cmpb SIGN_POS,PARAM5
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jne LCheck_truncate_53 /* If negative then up==truncate */
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jmp LCheck_53_round_up
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LDown_53:
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cmpb SIGN_POS,PARAM5
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je LCheck_truncate_53 /* If positive then down==truncate */
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LCheck_53_round_up:
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movl %ebx,%ecx
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andl $0x000007ff,%ecx
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orl %edx,%ecx
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jnz LDo_53_round_up
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jmp L_Re_normalise
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LRound_nearest_53:
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/* Do rounding of the 53rd bit if needed (nearest or even) */
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movl %ebx,%ecx
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andl $0x000007ff,%ecx
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cmpl $0x00000400,%ecx
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jc LCheck_truncate_53 /* less than half, no increment needed */
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jnz LGreater_Half_53 /* greater than half, increment needed */
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/* Possibly half, we need to check the ls bits */
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orl %edx,%edx
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jnz LGreater_Half_53 /* greater than half, increment needed */
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/* Exactly half, increment only if 53rd bit is 1 (round to even) */
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testl $0x00000800,%ebx
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jz LTruncate_53
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LGreater_Half_53: /* Rounding: increment at the 53rd bit */
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LDo_53_round_up:
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movb LOST_UP,FPU_bits_lost
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andl $0xfffff800,%ebx /* Truncate to 53 bits */
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addl $0x00000800,%ebx
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adcl $0,%eax
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jmp LCheck_Round_Overflow
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LCheck_truncate_53:
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movl %ebx,%ecx
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andl $0x000007ff,%ecx
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orl %edx,%ecx
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jz L_Re_normalise
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LTruncate_53:
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movb LOST_DOWN,FPU_bits_lost
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andl $0xfffff800,%ebx /* Truncate to 53 bits */
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jmp L_Re_normalise
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/* Round etc to 64 bit precision */
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LRound_To_64:
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movl %esi,%ecx
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andl CW_RC,%ecx
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cmpl RC_RND,%ecx
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je LRound_nearest_64
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cmpl RC_CHOP,%ecx
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je LCheck_truncate_64
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cmpl RC_UP,%ecx /* Towards +infinity */
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je LUp_64
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cmpl RC_DOWN,%ecx /* Towards -infinity */
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je LDown_64
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#ifdef PARANOID
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jmp L_bugged_round64
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#endif /* PARANOID */
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LUp_64:
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cmpb SIGN_POS,PARAM5
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jne LCheck_truncate_64 /* If negative then up==truncate */
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orl %edx,%edx
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jnz LDo_64_round_up
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jmp L_Re_normalise
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LDown_64:
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cmpb SIGN_POS,PARAM5
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je LCheck_truncate_64 /* If positive then down==truncate */
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orl %edx,%edx
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jnz LDo_64_round_up
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jmp L_Re_normalise
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LRound_nearest_64:
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cmpl $0x80000000,%edx
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jc LCheck_truncate_64
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jne LDo_64_round_up
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/* Now test for round-to-even */
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testb $1,%bl
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jz LCheck_truncate_64
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LDo_64_round_up:
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movb LOST_UP,FPU_bits_lost
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addl $1,%ebx
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adcl $0,%eax
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LCheck_Round_Overflow:
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jnc L_Re_normalise
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/* Overflow, adjust the result (significand to 1.0) */
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rcrl $1,%eax
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rcrl $1,%ebx
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incw EXP(%edi)
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jmp L_Re_normalise
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LCheck_truncate_64:
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orl %edx,%edx
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jz L_Re_normalise
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LTruncate_64:
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movb LOST_DOWN,FPU_bits_lost
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L_Re_normalise:
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testb $0xff,FPU_denormal
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jnz Normalise_result
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L_Normalised:
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movl TAG_Valid,%edx
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L_deNormalised:
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cmpb LOST_UP,FPU_bits_lost
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je L_precision_lost_up
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cmpb LOST_DOWN,FPU_bits_lost
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je L_precision_lost_down
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L_no_precision_loss:
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/* store the result */
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L_Store_significand:
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movl %eax,SIGH(%edi)
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movl %ebx,SIGL(%edi)
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cmpw EXP_OVER,EXP(%edi)
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jge L_overflow
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movl %edx,%eax
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/* Convert the exponent to 80x87 form. */
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addw EXTENDED_Ebias,EXP(%edi)
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andw $0x7fff,EXP(%edi)
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fpu_reg_round_signed_special_exit:
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cmpb SIGN_POS,PARAM5
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je fpu_reg_round_special_exit
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orw $0x8000,EXP(%edi) /* Negative sign for the result. */
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fpu_reg_round_special_exit:
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#ifndef NON_REENTRANT_FPU
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popl %ebx /* adjust the stack pointer */
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#endif /* NON_REENTRANT_FPU */
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fpu_Arith_exit:
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popl %ebx
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popl %edi
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popl %esi
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leave
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ret
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/*
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* Set the FPU status flags to represent precision loss due to
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* round-up.
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*/
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L_precision_lost_up:
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push %edx
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push %eax
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call set_precision_flag_up
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popl %eax
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popl %edx
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jmp L_no_precision_loss
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/*
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* Set the FPU status flags to represent precision loss due to
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* truncation.
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*/
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L_precision_lost_down:
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push %edx
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push %eax
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call set_precision_flag_down
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popl %eax
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popl %edx
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jmp L_no_precision_loss
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/*
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* The number is a denormal (which might get rounded up to a normal)
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* Shift the number right the required number of bits, which will
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* have to be undone later...
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*/
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L_Make_denorm:
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/* The action to be taken depends upon whether the underflow
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exception is masked */
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testb CW_Underflow,%cl /* Underflow mask. */
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jz Unmasked_underflow /* Do not make a denormal. */
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movb DENORMAL,FPU_denormal
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pushl %ecx /* Save */
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movw EXP_UNDER+1,%cx
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subw EXP(%edi),%cx
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cmpw $64,%cx /* shrd only works for 0..31 bits */
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jnc Denorm_shift_more_than_63
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cmpw $32,%cx /* shrd only works for 0..31 bits */
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jnc Denorm_shift_more_than_32
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/*
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* We got here without jumps by assuming that the most common requirement
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* is for a small de-normalising shift.
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* Shift by [1..31] bits
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*/
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addw %cx,EXP(%edi)
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orl %edx,%edx /* extension */
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setne %ch /* Save whether %edx is non-zero */
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xorl %edx,%edx
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shrd %cl,%ebx,%edx
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shrd %cl,%eax,%ebx
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shr %cl,%eax
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orb %ch,%dl
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popl %ecx
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jmp Denorm_done
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/* Shift by [32..63] bits */
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Denorm_shift_more_than_32:
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addw %cx,EXP(%edi)
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subb $32,%cl
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orl %edx,%edx
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setne %ch
|
|
orb %ch,%bl
|
|
xorl %edx,%edx
|
|
shrd %cl,%ebx,%edx
|
|
shrd %cl,%eax,%ebx
|
|
shr %cl,%eax
|
|
orl %edx,%edx /* test these 32 bits */
|
|
setne %cl
|
|
orb %ch,%bl
|
|
orb %cl,%bl
|
|
movl %ebx,%edx
|
|
movl %eax,%ebx
|
|
xorl %eax,%eax
|
|
popl %ecx
|
|
jmp Denorm_done
|
|
|
|
/* Shift by [64..) bits */
|
|
Denorm_shift_more_than_63:
|
|
cmpw $64,%cx
|
|
jne Denorm_shift_more_than_64
|
|
|
|
/* Exactly 64 bit shift */
|
|
addw %cx,EXP(%edi)
|
|
xorl %ecx,%ecx
|
|
orl %edx,%edx
|
|
setne %cl
|
|
orl %ebx,%ebx
|
|
setne %ch
|
|
orb %ch,%cl
|
|
orb %cl,%al
|
|
movl %eax,%edx
|
|
xorl %eax,%eax
|
|
xorl %ebx,%ebx
|
|
popl %ecx
|
|
jmp Denorm_done
|
|
|
|
Denorm_shift_more_than_64:
|
|
movw EXP_UNDER+1,EXP(%edi)
|
|
/* This is easy, %eax must be non-zero, so.. */
|
|
movl $1,%edx
|
|
xorl %eax,%eax
|
|
xorl %ebx,%ebx
|
|
popl %ecx
|
|
jmp Denorm_done
|
|
|
|
|
|
Unmasked_underflow:
|
|
movb UNMASKED_UNDERFLOW,FPU_denormal
|
|
jmp Denorm_done
|
|
|
|
|
|
/* Undo the de-normalisation. */
|
|
Normalise_result:
|
|
cmpb UNMASKED_UNDERFLOW,FPU_denormal
|
|
je Signal_underflow
|
|
|
|
/* The number must be a denormal if we got here. */
|
|
#ifdef PARANOID
|
|
/* But check it... just in case. */
|
|
cmpw EXP_UNDER+1,EXP(%edi)
|
|
jne L_norm_bugged
|
|
#endif /* PARANOID */
|
|
|
|
#ifdef PECULIAR_486
|
|
/*
|
|
* This implements a special feature of 80486 behaviour.
|
|
* Underflow will be signalled even if the number is
|
|
* not a denormal after rounding.
|
|
* This difference occurs only for masked underflow, and not
|
|
* in the unmasked case.
|
|
* Actual 80486 behaviour differs from this in some circumstances.
|
|
*/
|
|
orl %eax,%eax /* ms bits */
|
|
js LPseudoDenormal /* Will be masked underflow */
|
|
#else
|
|
orl %eax,%eax /* ms bits */
|
|
js L_Normalised /* No longer a denormal */
|
|
#endif /* PECULIAR_486 */
|
|
|
|
jnz LDenormal_adj_exponent
|
|
|
|
orl %ebx,%ebx
|
|
jz L_underflow_to_zero /* The contents are zero */
|
|
|
|
LDenormal_adj_exponent:
|
|
decw EXP(%edi)
|
|
|
|
LPseudoDenormal:
|
|
testb $0xff,FPU_bits_lost /* bits lost == underflow */
|
|
movl TAG_Special,%edx
|
|
jz L_deNormalised
|
|
|
|
/* There must be a masked underflow */
|
|
push %eax
|
|
pushl EX_Underflow
|
|
call EXCEPTION
|
|
popl %eax
|
|
popl %eax
|
|
movl TAG_Special,%edx
|
|
jmp L_deNormalised
|
|
|
|
|
|
/*
|
|
* The operations resulted in a number too small to represent.
|
|
* Masked response.
|
|
*/
|
|
L_underflow_to_zero:
|
|
push %eax
|
|
call set_precision_flag_down
|
|
popl %eax
|
|
|
|
push %eax
|
|
pushl EX_Underflow
|
|
call EXCEPTION
|
|
popl %eax
|
|
popl %eax
|
|
|
|
/* Reduce the exponent to EXP_UNDER */
|
|
movw EXP_UNDER,EXP(%edi)
|
|
movl TAG_Zero,%edx
|
|
jmp L_Store_significand
|
|
|
|
|
|
/* The operations resulted in a number too large to represent. */
|
|
L_overflow:
|
|
addw EXTENDED_Ebias,EXP(%edi) /* Set for unmasked response. */
|
|
push %edi
|
|
call arith_overflow
|
|
pop %edi
|
|
jmp fpu_reg_round_signed_special_exit
|
|
|
|
|
|
Signal_underflow:
|
|
/* The number may have been changed to a non-denormal */
|
|
/* by the rounding operations. */
|
|
cmpw EXP_UNDER,EXP(%edi)
|
|
jle Do_unmasked_underflow
|
|
|
|
jmp L_Normalised
|
|
|
|
Do_unmasked_underflow:
|
|
/* Increase the exponent by the magic number */
|
|
addw $(3*(1<<13)),EXP(%edi)
|
|
push %eax
|
|
pushl EX_Underflow
|
|
call EXCEPTION
|
|
popl %eax
|
|
popl %eax
|
|
jmp L_Normalised
|
|
|
|
|
|
#ifdef PARANOID
|
|
#ifdef PECULIAR_486
|
|
L_bugged_denorm_486:
|
|
pushl EX_INTERNAL|0x236
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
#else
|
|
L_bugged_denorm:
|
|
pushl EX_INTERNAL|0x230
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
#endif /* PECULIAR_486 */
|
|
|
|
L_bugged_round24:
|
|
pushl EX_INTERNAL|0x231
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
|
|
L_bugged_round53:
|
|
pushl EX_INTERNAL|0x232
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
|
|
L_bugged_round64:
|
|
pushl EX_INTERNAL|0x233
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
|
|
L_norm_bugged:
|
|
pushl EX_INTERNAL|0x234
|
|
call EXCEPTION
|
|
popl %ebx
|
|
jmp L_exception_exit
|
|
|
|
L_entry_bugged:
|
|
pushl EX_INTERNAL|0x235
|
|
call EXCEPTION
|
|
popl %ebx
|
|
L_exception_exit:
|
|
mov $-1,%eax
|
|
jmp fpu_reg_round_special_exit
|
|
#endif /* PARANOID */
|
|
|
|
ENDPROC(FPU_round)
|