[PATCH] ppc32: emulate load/store string instructions
From: Kumar Gala <hidden>
Date: 2005-03-11 22:14:10
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 <redacted> --- 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; }