2005-03-11 22:14:10

by Kumar Gala

Subject: [PATCH] ppc32: emulate load/store string instructions

Andrew,

Some Book-E implementations (e500) do not implement the userland
load/store string instructions. Apparently these instructions are rather
painful to implement do to the fact that they modify the destination
register differently then ever other instruction. Matt did the inital
work some time ago, and I finally got around to cleaning it up.

Signed-off-by: Matt McClintock
Signed-off-by: Kumar Gala <[email protected]>

---

diff -Nru a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
--- a/arch/ppc/kernel/traps.c 2005-03-11 15:07:28 -06:00
+++ b/arch/ppc/kernel/traps.c 2005-03-11 15:07:28 -06:00
@@ -389,6 +389,87 @@
#define INST_MCRXR 0x7c000400
#define INST_MCRXR_MASK 0x7c0007fe

+#define INST_STRING 0x7c00042a
+#define INST_STRING_MASK 0x7c0007fe
+#define INST_STRING_GEN_MASK 0x7c00067e
+#define INST_LSWI 0x7c0004aa
+#define INST_LSWX 0x7c00042a
+#define INST_STSWI 0x7c0005aa
+#define INST_STSWX 0x7c00052a
+
+static int emulate_string_inst(struct pt_regs *regs, u32 instword)
+{
+ u8 rT = (instword >> 21) & 0x1f;
+ u8 rA = (instword >> 16) & 0x1f;
+ u8 NB_RB = (instword >> 11) & 0x1f;
+ u32 num_bytes;
+ u32 EA;
+ int pos = 0;
+
+ /* Early out if we are an invalid form of lswx */
+ if ((instword & INST_STRING_MASK) == INST_LSWX)
+ if ((rA >= rT) || (NB_RB >= rT) || (rT == rA) || (rT == NB_RB))
+ return -EINVAL;
+
+ /* Early out if we are an invalid form of lswi */
+ if ((instword & INST_STRING_MASK) == INST_LSWX)
+ if ((rA >= rT) || (rT == rA))
+ return -EINVAL;
+
+ EA = (rA == 0) ? 0 : regs->gpr[rA];
+
+ switch (instword & INST_STRING_MASK) {
+ case INST_LSWX:
+ case INST_STSWX:
+ EA += NB_RB;
+ num_bytes = regs->xer & 0x7f;
+ break;
+ case INST_LSWI:
+ case INST_STSWI:
+ num_bytes = (NB_RB == 0) ? 32 : NB_RB;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ while (num_bytes != 0)
+ {
+ u8 val;
+ u32 shift = 8 * (3 - (pos & 0x3));
+
+ switch ((instword & INST_STRING_MASK)) {
+ case INST_LSWX:
+ case INST_LSWI:
+ if (get_user(val, (u8 __user *)EA))
+ return -EFAULT;
+ /* first time updating this reg,
+ * zero it out */
+ if (pos == 0)
+ regs->gpr[rT] = 0;
+ regs->gpr[rT] |= val << shift;
+ break;
+ case INST_STSWI:
+ case INST_STSWX:
+ val = regs->gpr[rT] >> shift;
+ if (put_user(val, (u8 __user *)EA))
+ return -EFAULT;
+ break;
+ }
+ /* move EA to next address */
+ EA += 1;
+ num_bytes--;
+
+ /* manage our position within the register */
+ if (++pos == 4) {
+ pos = 0;
+ if (++rT == 32)
+ rT = 0;
+ }
+ }
+
+ return 0;
+}
+
static int emulate_instruction(struct pt_regs *regs)
{
u32 instword;
@@ -422,6 +503,10 @@
regs->xer &= ~0xf0000000UL;
return 0;
}
+
+ /* Emulate load/store string insn. */
+ if ((instword & INST_STRING_GEN_MASK) == INST_STRING)
+ return emulate_string_inst(regs, instword);

return -EINVAL;
}

2005-03-21 13:55:17

by Segher Boessenkool

Subject: Re: [PATCH] ppc32: emulate load/store string instructions

> + /* Early out if we are an invalid form of lswi */
> + if ((instword & INST_STRING_MASK) == INST_LSWX)

Typo --------------------------------------------^


Segher

2005-03-21 15:29:22

by Kumar Gala

Subject: Re: [PATCH] ppc32: emulate load/store string instructions

Thanks, will send a patch to fix that.

- kumar

On Mar 19, 2005, at 8:36 AM, Segher Boessenkool wrote:

>> + /* Early out if we are an invalid form of lswi */
>> + if ((instword & INST_STRING_MASK) == INST_LSWX)
>
> Typo --------------------------------------------^
>
>
> Segher

2005-03-21 15:39:56

by Kumar Gala

Subject: [PATCH] ppc32: typo fix in load/store string emulation

Andrew,

Patch fixes a typo in the emulation of load/store string emulations
pointed out by Segher Boessenkool.


Signed-off-by: Kumar Gala <[email protected]>

---
diff -Nru a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
--- a/arch/ppc/kernel/traps.c 2005-03-21 09:36:28 -06:00
+++ b/arch/ppc/kernel/traps.c 2005-03-21 09:36:28 -06:00
@@ -412,7 +412,7 @@
return -EINVAL;

/* Early out if we are an invalid form of lswi */
- if ((instword & INST_STRING_MASK) == INST_LSWX)
+ if ((instword & INST_STRING_MASK) == INST_LSWI)
if ((rA >= rT) || (rT == rA))
return -EINVAL;