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authorPaul Mackerras <paulus@samba.org>2007-08-10 14:07:38 +1000
committerPaul Mackerras <paulus@samba.org>2007-08-17 11:01:55 +1000
commitc6d4267eced79775399f256fbb4adb671e9b597e (patch)
tree211acc4464342ba2d87365367c3afb4ce509038d /arch/powerpc/kernel/align.c
parent09a54101e15f43607722dee55f33d1962653c6cb (diff)
[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>
Diffstat (limited to 'arch/powerpc/kernel/align.c')
-rw-r--r--arch/powerpc/kernel/align.c57
1 files changed, 49 insertions, 8 deletions
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index 5c9ff7f5c44..4c47f9cc0d9 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -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 */