linux/arch/x86/math-emu/reg_round.S
Jiri Slaby bd6be579a7 x86/fpu/math-emu: Add ENDPROC to functions
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>
2017-08-29 13:23:30 +02:00

711 lines
18 KiB
ArmAsm

.file "reg_round.S"
/*---------------------------------------------------------------------------+
| reg_round.S |
| |
| Rounding/truncation/etc for FPU basic arithmetic functions. |
| |
| Copyright (C) 1993,1995,1997 |
| W. Metzenthen, 22 Parker St, Ormond, Vic 3163, |
| Australia. E-mail billm@suburbia.net |
| |
| This code has four possible entry points. |
| The following must be entered by a jmp instruction: |
| fpu_reg_round, fpu_reg_round_sqrt, and fpu_Arith_exit. |
| |
| The FPU_round entry point is intended to be used by C code. |
| From C, call as: |
| int FPU_round(FPU_REG *arg, unsigned int extent, unsigned int control_w) |
| |
| Return value is the tag of the answer, or-ed with FPU_Exception if |
| one was raised, or -1 on internal error. |
| |
| For correct "up" and "down" rounding, the argument must have the correct |
| sign. |
| |
+---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------+
| Four entry points. |
| |
| Needed by both the fpu_reg_round and fpu_reg_round_sqrt entry points: |
| %eax:%ebx 64 bit significand |
| %edx 32 bit extension of the significand |
| %edi pointer to an FPU_REG for the result to be stored |
| stack calling function must have set up a C stack frame and |
| pushed %esi, %edi, and %ebx |
| |
| Needed just for the fpu_reg_round_sqrt entry point: |
| %cx A control word in the same format as the FPU control word. |
| Otherwise, PARAM4 must give such a value. |
| |
| |
| The significand and its extension are assumed to be exact in the |
| following sense: |
| If the significand by itself is the exact result then the significand |
| extension (%edx) must contain 0, otherwise the significand extension |
| must be non-zero. |
| If the significand extension is non-zero then the significand is |
| smaller than the magnitude of the correct exact result by an amount |
| greater than zero and less than one ls bit of the significand. |
| The significand extension is only required to have three possible |
| non-zero values: |
| less than 0x80000000 <=> the significand is less than 1/2 an ls |
| bit smaller than the magnitude of the |
| true exact result. |
| exactly 0x80000000 <=> the significand is exactly 1/2 an ls bit |
| smaller than the magnitude of the true |
| exact result. |
| greater than 0x80000000 <=> the significand is more than 1/2 an ls |
| bit smaller than the magnitude of the |
| true exact result. |
| |
+---------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------+
| The code in this module has become quite complex, but it should handle |
| all of the FPU flags which are set at this stage of the basic arithmetic |
| computations. |
| There are a few rare cases where the results are not set identically to |
| a real FPU. These require a bit more thought because at this stage the |
| results of the code here appear to be more consistent... |
| This may be changed in a future version. |
+---------------------------------------------------------------------------*/
#include "fpu_emu.h"
#include "exception.h"
#include "control_w.h"
/* Flags for FPU_bits_lost */
#define LOST_DOWN $1
#define LOST_UP $2
/* Flags for FPU_denormal */
#define DENORMAL $1
#define UNMASKED_UNDERFLOW $2
#ifndef NON_REENTRANT_FPU
/* Make the code re-entrant by putting
local storage on the stack: */
#define FPU_bits_lost (%esp)
#define FPU_denormal 1(%esp)
#else
/* Not re-entrant, so we can gain speed by putting
local storage in a static area: */
.data
.align 4,0
FPU_bits_lost:
.byte 0
FPU_denormal:
.byte 0
#endif /* NON_REENTRANT_FPU */
.text
.globl fpu_reg_round
.globl fpu_Arith_exit
/* Entry point when called from C */
ENTRY(FPU_round)
pushl %ebp
movl %esp,%ebp
pushl %esi
pushl %edi
pushl %ebx
movl PARAM1,%edi
movl SIGH(%edi),%eax
movl SIGL(%edi),%ebx
movl PARAM2,%edx
fpu_reg_round: /* Normal entry point */
movl PARAM4,%ecx
#ifndef NON_REENTRANT_FPU
pushl %ebx /* adjust the stack pointer */
#endif /* NON_REENTRANT_FPU */
#ifdef PARANOID
/* Cannot use this here yet */
/* orl %eax,%eax */
/* jns L_entry_bugged */
#endif /* PARANOID */
cmpw EXP_UNDER,EXP(%edi)
jle L_Make_denorm /* The number is a de-normal */
movb $0,FPU_denormal /* 0 -> not a de-normal */
Denorm_done:
movb $0,FPU_bits_lost /* No bits yet lost in rounding */
movl %ecx,%esi
andl CW_PC,%ecx
cmpl PR_64_BITS,%ecx
je LRound_To_64
cmpl PR_53_BITS,%ecx
je LRound_To_53
cmpl PR_24_BITS,%ecx
je LRound_To_24
#ifdef PECULIAR_486
/* With the precision control bits set to 01 "(reserved)", a real 80486
behaves as if the precision control bits were set to 11 "64 bits" */
cmpl PR_RESERVED_BITS,%ecx
je LRound_To_64
#ifdef PARANOID
jmp L_bugged_denorm_486
#endif /* PARANOID */
#else
#ifdef PARANOID
jmp L_bugged_denorm /* There is no bug, just a bad control word */
#endif /* PARANOID */
#endif /* PECULIAR_486 */
/* Round etc to 24 bit precision */
LRound_To_24:
movl %esi,%ecx
andl CW_RC,%ecx
cmpl RC_RND,%ecx
je LRound_nearest_24
cmpl RC_CHOP,%ecx
je LCheck_truncate_24
cmpl RC_UP,%ecx /* Towards +infinity */
je LUp_24
cmpl RC_DOWN,%ecx /* Towards -infinity */
je LDown_24
#ifdef PARANOID
jmp L_bugged_round24
#endif /* PARANOID */
LUp_24:
cmpb SIGN_POS,PARAM5
jne LCheck_truncate_24 /* If negative then up==truncate */
jmp LCheck_24_round_up
LDown_24:
cmpb SIGN_POS,PARAM5
je LCheck_truncate_24 /* If positive then down==truncate */
LCheck_24_round_up:
movl %eax,%ecx
andl $0x000000ff,%ecx
orl %ebx,%ecx
orl %edx,%ecx
jnz LDo_24_round_up
jmp L_Re_normalise
LRound_nearest_24:
/* Do rounding of the 24th bit if needed (nearest or even) */
movl %eax,%ecx
andl $0x000000ff,%ecx
cmpl $0x00000080,%ecx
jc LCheck_truncate_24 /* less than half, no increment needed */
jne LGreater_Half_24 /* greater than half, increment needed */
/* Possibly half, we need to check the ls bits */
orl %ebx,%ebx
jnz LGreater_Half_24 /* greater than half, increment needed */
orl %edx,%edx
jnz LGreater_Half_24 /* greater than half, increment needed */
/* Exactly half, increment only if 24th bit is 1 (round to even) */
testl $0x00000100,%eax
jz LDo_truncate_24
LGreater_Half_24: /* Rounding: increment at the 24th bit */
LDo_24_round_up:
andl $0xffffff00,%eax /* Truncate to 24 bits */
xorl %ebx,%ebx
movb LOST_UP,FPU_bits_lost
addl $0x00000100,%eax
jmp LCheck_Round_Overflow
LCheck_truncate_24:
movl %eax,%ecx
andl $0x000000ff,%ecx
orl %ebx,%ecx
orl %edx,%ecx
jz L_Re_normalise /* No truncation needed */
LDo_truncate_24:
andl $0xffffff00,%eax /* Truncate to 24 bits */
xorl %ebx,%ebx
movb LOST_DOWN,FPU_bits_lost
jmp L_Re_normalise
/* Round etc to 53 bit precision */
LRound_To_53:
movl %esi,%ecx
andl CW_RC,%ecx
cmpl RC_RND,%ecx
je LRound_nearest_53
cmpl RC_CHOP,%ecx
je LCheck_truncate_53
cmpl RC_UP,%ecx /* Towards +infinity */
je LUp_53
cmpl RC_DOWN,%ecx /* Towards -infinity */
je LDown_53
#ifdef PARANOID
jmp L_bugged_round53
#endif /* PARANOID */
LUp_53:
cmpb SIGN_POS,PARAM5
jne LCheck_truncate_53 /* If negative then up==truncate */
jmp LCheck_53_round_up
LDown_53:
cmpb SIGN_POS,PARAM5
je LCheck_truncate_53 /* If positive then down==truncate */
LCheck_53_round_up:
movl %ebx,%ecx
andl $0x000007ff,%ecx
orl %edx,%ecx
jnz LDo_53_round_up
jmp L_Re_normalise
LRound_nearest_53:
/* Do rounding of the 53rd bit if needed (nearest or even) */
movl %ebx,%ecx
andl $0x000007ff,%ecx
cmpl $0x00000400,%ecx
jc LCheck_truncate_53 /* less than half, no increment needed */
jnz LGreater_Half_53 /* greater than half, increment needed */
/* Possibly half, we need to check the ls bits */
orl %edx,%edx
jnz LGreater_Half_53 /* greater than half, increment needed */
/* Exactly half, increment only if 53rd bit is 1 (round to even) */
testl $0x00000800,%ebx
jz LTruncate_53
LGreater_Half_53: /* Rounding: increment at the 53rd bit */
LDo_53_round_up:
movb LOST_UP,FPU_bits_lost
andl $0xfffff800,%ebx /* Truncate to 53 bits */
addl $0x00000800,%ebx
adcl $0,%eax
jmp LCheck_Round_Overflow
LCheck_truncate_53:
movl %ebx,%ecx
andl $0x000007ff,%ecx
orl %edx,%ecx
jz L_Re_normalise
LTruncate_53:
movb LOST_DOWN,FPU_bits_lost
andl $0xfffff800,%ebx /* Truncate to 53 bits */
jmp L_Re_normalise
/* Round etc to 64 bit precision */
LRound_To_64:
movl %esi,%ecx
andl CW_RC,%ecx
cmpl RC_RND,%ecx
je LRound_nearest_64
cmpl RC_CHOP,%ecx
je LCheck_truncate_64
cmpl RC_UP,%ecx /* Towards +infinity */
je LUp_64
cmpl RC_DOWN,%ecx /* Towards -infinity */
je LDown_64
#ifdef PARANOID
jmp L_bugged_round64
#endif /* PARANOID */
LUp_64:
cmpb SIGN_POS,PARAM5
jne LCheck_truncate_64 /* If negative then up==truncate */
orl %edx,%edx
jnz LDo_64_round_up
jmp L_Re_normalise
LDown_64:
cmpb SIGN_POS,PARAM5
je LCheck_truncate_64 /* If positive then down==truncate */
orl %edx,%edx
jnz LDo_64_round_up
jmp L_Re_normalise
LRound_nearest_64:
cmpl $0x80000000,%edx
jc LCheck_truncate_64
jne LDo_64_round_up
/* Now test for round-to-even */
testb $1,%bl
jz LCheck_truncate_64
LDo_64_round_up:
movb LOST_UP,FPU_bits_lost
addl $1,%ebx
adcl $0,%eax
LCheck_Round_Overflow:
jnc L_Re_normalise
/* Overflow, adjust the result (significand to 1.0) */
rcrl $1,%eax
rcrl $1,%ebx
incw EXP(%edi)
jmp L_Re_normalise
LCheck_truncate_64:
orl %edx,%edx
jz L_Re_normalise
LTruncate_64:
movb LOST_DOWN,FPU_bits_lost
L_Re_normalise:
testb $0xff,FPU_denormal
jnz Normalise_result
L_Normalised:
movl TAG_Valid,%edx
L_deNormalised:
cmpb LOST_UP,FPU_bits_lost
je L_precision_lost_up
cmpb LOST_DOWN,FPU_bits_lost
je L_precision_lost_down
L_no_precision_loss:
/* store the result */
L_Store_significand:
movl %eax,SIGH(%edi)
movl %ebx,SIGL(%edi)
cmpw EXP_OVER,EXP(%edi)
jge L_overflow
movl %edx,%eax
/* Convert the exponent to 80x87 form. */
addw EXTENDED_Ebias,EXP(%edi)
andw $0x7fff,EXP(%edi)
fpu_reg_round_signed_special_exit:
cmpb SIGN_POS,PARAM5
je fpu_reg_round_special_exit
orw $0x8000,EXP(%edi) /* Negative sign for the result. */
fpu_reg_round_special_exit:
#ifndef NON_REENTRANT_FPU
popl %ebx /* adjust the stack pointer */
#endif /* NON_REENTRANT_FPU */
fpu_Arith_exit:
popl %ebx
popl %edi
popl %esi
leave
ret
/*
* Set the FPU status flags to represent precision loss due to
* round-up.
*/
L_precision_lost_up:
push %edx
push %eax
call set_precision_flag_up
popl %eax
popl %edx
jmp L_no_precision_loss
/*
* Set the FPU status flags to represent precision loss due to
* truncation.
*/
L_precision_lost_down:
push %edx
push %eax
call set_precision_flag_down
popl %eax
popl %edx
jmp L_no_precision_loss
/*
* The number is a denormal (which might get rounded up to a normal)
* Shift the number right the required number of bits, which will
* have to be undone later...
*/
L_Make_denorm:
/* The action to be taken depends upon whether the underflow
exception is masked */
testb CW_Underflow,%cl /* Underflow mask. */
jz Unmasked_underflow /* Do not make a denormal. */
movb DENORMAL,FPU_denormal
pushl %ecx /* Save */
movw EXP_UNDER+1,%cx
subw EXP(%edi),%cx
cmpw $64,%cx /* shrd only works for 0..31 bits */
jnc Denorm_shift_more_than_63
cmpw $32,%cx /* shrd only works for 0..31 bits */
jnc Denorm_shift_more_than_32
/*
* We got here without jumps by assuming that the most common requirement
* is for a small de-normalising shift.
* Shift by [1..31] bits
*/
addw %cx,EXP(%edi)
orl %edx,%edx /* extension */
setne %ch /* Save whether %edx is non-zero */
xorl %edx,%edx
shrd %cl,%ebx,%edx
shrd %cl,%eax,%ebx
shr %cl,%eax
orb %ch,%dl
popl %ecx
jmp Denorm_done
/* Shift by [32..63] bits */
Denorm_shift_more_than_32:
addw %cx,EXP(%edi)
subb $32,%cl
orl %edx,%edx
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)