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powerpc: Add little endian support to alignment handler
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Handle most unaligned load and store faults in little
endian mode. Strings, multiples and VSX are not supported.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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Anton Blanchard authored and Benjamin Herrenschmidt committed Oct 11, 2013
1 parent a5841a4 commit 835e206
Showing 1 changed file with 63 additions and 30 deletions.
93 changes: 63 additions & 30 deletions arch/powerpc/kernel/align.c
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Original file line number Diff line number Diff line change
Expand Up @@ -262,6 +262,7 @@ static int emulate_dcbz(struct pt_regs *regs, unsigned char __user *addr)

#define SWIZ_PTR(p) ((unsigned char __user *)((p) ^ swiz))

#ifdef __BIG_ENDIAN__
static int emulate_multiple(struct pt_regs *regs, unsigned char __user *addr,
unsigned int reg, unsigned int nb,
unsigned int flags, unsigned int instr,
Expand Down Expand Up @@ -390,6 +391,7 @@ static int emulate_fp_pair(unsigned char __user *addr, unsigned int reg,
return -EFAULT;
return 1; /* exception handled and fixed up */
}
#endif

#ifdef CONFIG_SPE

Expand Down Expand Up @@ -628,7 +630,7 @@ static int emulate_spe(struct pt_regs *regs, unsigned int reg,
}
#endif /* CONFIG_SPE */

#ifdef CONFIG_VSX
#if defined(CONFIG_VSX) && defined(__BIG_ENDIAN__)
/*
* Emulate VSX instructions...
*/
Expand Down Expand Up @@ -702,18 +704,28 @@ int fix_alignment(struct pt_regs *regs)
unsigned int dsisr;
unsigned char __user *addr;
unsigned long p, swiz;
int ret;
union {
int ret, i;
union data {
u64 ll;
double dd;
unsigned char v[8];
struct {
#ifdef __LITTLE_ENDIAN__
int low32;
unsigned hi32;
#else
unsigned hi32;
int low32;
#endif
} x32;
struct {
#ifdef __LITTLE_ENDIAN__
short low16;
unsigned char hi48[6];
#else
unsigned char hi48[6];
short low16;
#endif
} x16;
} data;

Expand Down Expand Up @@ -772,8 +784,9 @@ int fix_alignment(struct pt_regs *regs)

/* Byteswap little endian loads and stores */
swiz = 0;
if (regs->msr & MSR_LE) {
if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE)) {
flags ^= SW;
#ifdef __BIG_ENDIAN__
/*
* So-called "PowerPC little endian" mode works by
* swizzling addresses rather than by actually doing
Expand All @@ -786,11 +799,13 @@ int fix_alignment(struct pt_regs *regs)
*/
if (cpu_has_feature(CPU_FTR_PPC_LE))
swiz = 7;
#endif
}

/* DAR has the operand effective address */
addr = (unsigned char __user *)regs->dar;

#ifdef __BIG_ENDIAN__
#ifdef CONFIG_VSX
if ((instruction & 0xfc00003e) == 0x7c000018) {
unsigned int elsize;
Expand All @@ -810,7 +825,7 @@ int fix_alignment(struct pt_regs *regs)
elsize = 8;

flags = 0;
if (regs->msr & MSR_LE)
if ((regs->msr & MSR_LE) != (MSR_KERNEL & MSR_LE))
flags |= SW;
if (instruction & 0x100)
flags |= ST;
Expand All @@ -824,6 +839,9 @@ int fix_alignment(struct pt_regs *regs)
PPC_WARN_ALIGNMENT(vsx, regs);
return emulate_vsx(addr, reg, areg, regs, flags, nb, elsize);
}
#endif
#else
return -EFAULT;
#endif
/* A size of 0 indicates an instruction we don't support, with
* the exception of DCBZ which is handled as a special case here
Expand All @@ -839,9 +857,13 @@ int fix_alignment(struct pt_regs *regs)
* function
*/
if (flags & M) {
#ifdef __BIG_ENDIAN__
PPC_WARN_ALIGNMENT(multiple, regs);
return emulate_multiple(regs, addr, reg, nb,
flags, instr, swiz);
#else
return -EFAULT;
#endif
}

/* Verify the address of the operand */
Expand All @@ -860,8 +882,12 @@ int fix_alignment(struct pt_regs *regs)

/* Special case for 16-byte FP loads and stores */
if (nb == 16) {
#ifdef __BIG_ENDIAN__
PPC_WARN_ALIGNMENT(fp_pair, regs);
return emulate_fp_pair(addr, reg, flags);
#else
return -EFAULT;
#endif
}

PPC_WARN_ALIGNMENT(unaligned, regs);
Expand All @@ -870,24 +896,28 @@ int fix_alignment(struct pt_regs *regs)
* get it from register values
*/
if (!(flags & ST)) {
data.ll = 0;
ret = 0;
p = (unsigned long) addr;
unsigned int start = 0;

switch (nb) {
case 8:
ret |= __get_user_inatomic(data.v[0], SWIZ_PTR(p++));
ret |= __get_user_inatomic(data.v[1], SWIZ_PTR(p++));
ret |= __get_user_inatomic(data.v[2], SWIZ_PTR(p++));
ret |= __get_user_inatomic(data.v[3], SWIZ_PTR(p++));
case 4:
ret |= __get_user_inatomic(data.v[4], SWIZ_PTR(p++));
ret |= __get_user_inatomic(data.v[5], SWIZ_PTR(p++));
start = offsetof(union data, x32.low32);
break;
case 2:
ret |= __get_user_inatomic(data.v[6], SWIZ_PTR(p++));
ret |= __get_user_inatomic(data.v[7], SWIZ_PTR(p++));
if (unlikely(ret))
return -EFAULT;
start = offsetof(union data, x16.low16);
break;
}

data.ll = 0;
ret = 0;
p = (unsigned long)addr;

for (i = 0; i < nb; i++)
ret |= __get_user_inatomic(data.v[start + i],
SWIZ_PTR(p++));

if (unlikely(ret))
return -EFAULT;

} else if (flags & F) {
data.dd = current->thread.TS_FPR(reg);
if (flags & S) {
Expand Down Expand Up @@ -945,21 +975,24 @@ int fix_alignment(struct pt_regs *regs)

/* Store result to memory or update registers */
if (flags & ST) {
ret = 0;
p = (unsigned long) addr;
unsigned int start = 0;

switch (nb) {
case 8:
ret |= __put_user_inatomic(data.v[0], SWIZ_PTR(p++));
ret |= __put_user_inatomic(data.v[1], SWIZ_PTR(p++));
ret |= __put_user_inatomic(data.v[2], SWIZ_PTR(p++));
ret |= __put_user_inatomic(data.v[3], SWIZ_PTR(p++));
case 4:
ret |= __put_user_inatomic(data.v[4], SWIZ_PTR(p++));
ret |= __put_user_inatomic(data.v[5], SWIZ_PTR(p++));
start = offsetof(union data, x32.low32);
break;
case 2:
ret |= __put_user_inatomic(data.v[6], SWIZ_PTR(p++));
ret |= __put_user_inatomic(data.v[7], SWIZ_PTR(p++));
start = offsetof(union data, x16.low16);
break;
}

ret = 0;
p = (unsigned long)addr;

for (i = 0; i < nb; i++)
ret |= __put_user_inatomic(data.v[start + i],
SWIZ_PTR(p++));

if (unlikely(ret))
return -EFAULT;
} else if (flags & F)
Expand Down

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