summaryrefslogtreecommitdiff
path: root/arch/mips/math-emu/dsemul.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/mips/math-emu/dsemul.c')
-rw-r--r--arch/mips/math-emu/dsemul.c77
1 files changed, 52 insertions, 25 deletions
diff --git a/arch/mips/math-emu/dsemul.c b/arch/mips/math-emu/dsemul.c
index cbb36c14b155..46b964d2b79c 100644
--- a/arch/mips/math-emu/dsemul.c
+++ b/arch/mips/math-emu/dsemul.c
@@ -31,17 +31,41 @@ struct emuframe {
unsigned long epc;
};
+/*
+ * Set up an emulation frame for instruction IR, from a delay slot of
+ * a branch jumping to CPC. Return 0 if successful, -1 if no emulation
+ * required, otherwise a signal number causing a frame setup failure.
+ */
int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
{
+ int isa16 = get_isa16_mode(regs->cp0_epc);
+ mips_instruction break_math;
struct emuframe __user *fr;
int err;
- if ((get_isa16_mode(regs->cp0_epc) && ((ir >> 16) == MM_NOP16)) ||
- (ir == 0)) {
- /* NOP is easy */
- regs->cp0_epc = cpc;
- clear_delay_slot(regs);
- return 0;
+ /* NOP is easy */
+ if (ir == 0)
+ return -1;
+
+ /* microMIPS instructions */
+ if (isa16) {
+ union mips_instruction insn = { .word = ir };
+
+ /* NOP16 aka MOVE16 $0, $0 */
+ if ((ir >> 16) == MM_NOP16)
+ return -1;
+
+ /* ADDIUPC */
+ if (insn.mm_a_format.opcode == mm_addiupc_op) {
+ unsigned int rs;
+ s32 v;
+
+ rs = (((insn.mm_a_format.rs + 0x1e) & 0xf) + 2);
+ v = regs->cp0_epc & ~3;
+ v += insn.mm_a_format.simmediate << 2;
+ regs->regs[rs] = (long)v;
+ return -1;
+ }
}
pr_debug("dsemul %lx %lx\n", regs->cp0_epc, cpc);
@@ -55,14 +79,10 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
* Algorithmics used a system call instruction, and
* borrowed that vector. MIPS/Linux version is a bit
* more heavyweight in the interests of portability and
- * multiprocessor support. For Linux we generate a
- * an unaligned access and force an address error exception.
- *
- * For embedded systems (stand-alone) we prefer to use a
- * non-existing CP1 instruction. This prevents us from emulating
- * branches, but gives us a cleaner interface to the exception
- * handler (single entry point).
+ * multiprocessor support. For Linux we use a BREAK 514
+ * instruction causing a breakpoint exception.
*/
+ break_math = BREAK_MATH(isa16);
/* Ensure that the two instructions are in the same cache line */
fr = (struct emuframe __user *)
@@ -72,14 +92,18 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
if (unlikely(!access_ok(VERIFY_WRITE, fr, sizeof(struct emuframe))))
return SIGBUS;
- if (get_isa16_mode(regs->cp0_epc)) {
- err = __put_user(ir >> 16, (u16 __user *)(&fr->emul));
- err |= __put_user(ir & 0xffff, (u16 __user *)((long)(&fr->emul) + 2));
- err |= __put_user(BREAK_MATH >> 16, (u16 __user *)(&fr->badinst));
- err |= __put_user(BREAK_MATH & 0xffff, (u16 __user *)((long)(&fr->badinst) + 2));
+ if (isa16) {
+ err = __put_user(ir >> 16,
+ (u16 __user *)(&fr->emul));
+ err |= __put_user(ir & 0xffff,
+ (u16 __user *)((long)(&fr->emul) + 2));
+ err |= __put_user(break_math >> 16,
+ (u16 __user *)(&fr->badinst));
+ err |= __put_user(break_math & 0xffff,
+ (u16 __user *)((long)(&fr->badinst) + 2));
} else {
err = __put_user(ir, &fr->emul);
- err |= __put_user((mips_instruction)BREAK_MATH, &fr->badinst);
+ err |= __put_user(break_math, &fr->badinst);
}
err |= __put_user((mips_instruction)BD_COOKIE, &fr->cookie);
@@ -90,8 +114,7 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
return SIGBUS;
}
- regs->cp0_epc = ((unsigned long) &fr->emul) |
- get_isa16_mode(regs->cp0_epc);
+ regs->cp0_epc = (unsigned long)&fr->emul | isa16;
flush_cache_sigtramp((unsigned long)&fr->emul);
@@ -100,6 +123,7 @@ int mips_dsemul(struct pt_regs *regs, mips_instruction ir, unsigned long cpc)
int do_dsemulret(struct pt_regs *xcp)
{
+ int isa16 = get_isa16_mode(xcp->cp0_epc);
struct emuframe __user *fr;
unsigned long epc;
u32 insn, cookie;
@@ -122,16 +146,19 @@ int do_dsemulret(struct pt_regs *xcp)
* - Is the instruction pointed to by the EPC an BREAK_MATH?
* - Is the following memory word the BD_COOKIE?
*/
- if (get_isa16_mode(xcp->cp0_epc)) {
- err = __get_user(instr[0], (u16 __user *)(&fr->badinst));
- err |= __get_user(instr[1], (u16 __user *)((long)(&fr->badinst) + 2));
+ if (isa16) {
+ err = __get_user(instr[0],
+ (u16 __user *)(&fr->badinst));
+ err |= __get_user(instr[1],
+ (u16 __user *)((long)(&fr->badinst) + 2));
insn = (instr[0] << 16) | instr[1];
} else {
err = __get_user(insn, &fr->badinst);
}
err |= __get_user(cookie, &fr->cookie);
- if (unlikely(err || (insn != BREAK_MATH) || (cookie != BD_COOKIE))) {
+ if (unlikely(err ||
+ insn != BREAK_MATH(isa16) || cookie != BD_COOKIE)) {
MIPS_FPU_EMU_INC_STATS(errors);
return 0;
}