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[POWERPC] Handle alignment faults on new FP load/store instructions 

This adds code to handle alignment traps generated by the following
new floating-point load/store instructions, by emulating the
instruction in the kernel (as is done for other instructions that
generate alignment traps):

lfiwax	load floating-point as integer word algebraic indexed
stfiwx	store floating-point as integer word indexed
lfdp	load floating-point double pair
lfdpx	load floating-point double pair indexed
stfdp	store floating-point double pair
stfdpx	store floating-point double pair indexed

All these except stfiwx are new in POWER6.

lfdp/lfdpx/stfdp/stfdpx load and store 16 bytes of memory into an
even/odd FP register pair.  In little-endian mode each 8-byte value is
byte-reversed separately (i.e. not as a 16-byte unit).  lfiwax/stfiwx
load or store the lower 4 bytes of a floating-point register from/to
memory; lfiwax sets the upper 4 bytes of the FP register to the sign
extension of the value loaded.

Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Paul Mackerras 2007-08-10 14:07:38 +10:00
parent 09a54101e1
commit c6d4267ece
1 changed files with 49 additions and 8 deletions
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57
arch/powerpc/kernel/align.c
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@ -38,7 +38,7 @@ struct aligninfo {
/* Bits in the flags field */
#define LD 0 /* load */
#define ST 1 /* store */
#define SE 2 /* sign-extend value */
#define SE 2 /* sign-extend value, or FP ld/st as word */
#define F 4 /* to/from fp regs */
#define U 8 /* update index register */
#define M 0x10 /* multiple load/store */
@ -87,9 +87,9 @@ static struct aligninfo aligninfo[128] = {
{ 8, LD+F+U }, /* 00 1 1001: lfdu */
{ 4, ST+F+S+U }, /* 00 1 1010: stfsu */
{ 8, ST+F+U }, /* 00 1 1011: stfdu */
INVALID, /* 00 1 1100 */
{ 16, LD+F }, /* 00 1 1100: lfdp */
INVALID, /* 00 1 1101 */
INVALID, /* 00 1 1110 */
{ 16, ST+F }, /* 00 1 1110: stfdp */
INVALID, /* 00 1 1111 */
{ 8, LD }, /* 01 0 0000: ldx */
INVALID, /* 01 0 0001 */
@ -167,10 +167,10 @@ static struct aligninfo aligninfo[128] = {
{ 8, LD+F }, /* 11 0 1001: lfdx */
{ 4, ST+F+S }, /* 11 0 1010: stfsx */
{ 8, ST+F }, /* 11 0 1011: stfdx */
INVALID, /* 11 0 1100 */
{ 8, LD+M }, /* 11 0 1101: lmd */
INVALID, /* 11 0 1110 */
{ 8, ST+M }, /* 11 0 1111: stmd */
{ 16, LD+F }, /* 11 0 1100: lfdpx */
{ 4, LD+F+SE }, /* 11 0 1101: lfiwax */
{ 16, ST+F }, /* 11 0 1110: stfdpx */
{ 4, ST+F }, /* 11 0 1111: stfiwx */
{ 4, LD+U }, /* 11 1 0000: lwzux */
INVALID, /* 11 1 0001 */
{ 4, ST+U }, /* 11 1 0010: stwux */
@ -356,6 +356,42 @@ static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr,
return 1;
}
/*
* Emulate floating-point pair loads and stores.
* Only POWER6 has these instructions, and it does true little-endian,
* so we don't need the address swizzling.
*/
static int emulate_fp_pair(struct pt_regs *regs, unsigned char __user *addr,
unsigned int reg, unsigned int flags)
{
char *ptr = (char *) &current->thread.fpr[reg];
int i, ret;
if (!(flags & F))
return 0;
if (reg & 1)
return 0; /* invalid form: FRS/FRT must be even */
if (!(flags & SW)) {
/* not byte-swapped - easy */
if (!(flags & ST))
ret = __copy_from_user(ptr, addr, 16);
else
ret = __copy_to_user(addr, ptr, 16);
} else {
/* each FPR value is byte-swapped separately */
ret = 0;
for (i = 0; i < 16; ++i) {
if (!(flags & ST))
ret |= __get_user(ptr[i^7], addr + i);
else
ret |= __put_user(ptr[i^7], addr + i);
}
}
if (ret)
return -EFAULT;
return 1; /* exception handled and fixed up */
}
/*
* Called on alignment exception. Attempts to fixup
@ -471,6 +507,10 @@ int fix_alignment(struct pt_regs *regs)
flush_fp_to_thread(current);
}
/* Special case for 16-byte FP loads and stores */
if (nb == 16)
return emulate_fp_pair(regs, addr, reg, flags);
/* If we are loading, get the data from user space, else
* get it from register values
*/
@ -531,7 +571,8 @@ int fix_alignment(struct pt_regs *regs)
* or floating point single precision conversion
*/
switch (flags & ~(U|SW)) {
case LD+SE: /* sign extend */
case LD+SE: /* sign extending integer loads */
case LD+F+SE: /* sign extend for lfiwax */
if ( nb == 2 )
data.ll = data.x16.low16;
else /* nb must be 4 */