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MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6

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The MIPS R6 JR instruction is an alias to the JALR one, so it may
need emulation for non-R6 userlands.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
This commit is contained in:
Markos Chandras 2014-11-25 15:54:14 +00:00
commit 5f9f41c474
3 changed files with 15 additions and 2 deletions
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3
arch/mips/include/asm/branch.h
View file

@ -13,6 +13,9 @@
#include <asm/ptrace.h>
#include <asm/inst.h>
static int mipsr2_emulation = 0;
#define NO_R6EMU (cpu_has_mips_r6 && !mipsr2_emulation)
extern int __isa_exception_epc(struct pt_regs *regs);
extern int __compute_return_epc(struct pt_regs *regs);
extern int __compute_return_epc_for_insn(struct pt_regs *regs,

11
arch/mips/kernel/branch.c
View file

@ -417,6 +417,8 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
regs->regs[insn.r_format.rd] = epc + 8;
/* Fall through */
case jr_op:
if (NO_R6EMU && insn.r_format.func == jr_op)
goto sigill_r6;
regs->cp0_epc = regs->regs[insn.r_format.rs];
break;
}
@ -477,7 +479,7 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
case bposge32_op:
if (!cpu_has_dsp)
goto sigill;
goto sigill_dsp;
dspcontrol = rddsp(0x01);
@ -631,10 +633,15 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
return ret;
sigill:
sigill_dsp:
printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
force_sig(SIGBUS, current);
return -EFAULT;
sigill_r6:
pr_info("%s: R2 branch but r2-to-r6 emulator is not preset - sending SIGILL.\n",
current->comm);
force_sig(SIGILL, current);
return -EFAULT;
}
EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);

3
arch/mips/math-emu/cp1emu.c
View file

@ -448,6 +448,9 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
dec_insn.next_pc_inc;
/* Fall through */
case jr_op:
/* For R6, JR already emulated in jalr_op */
if (NO_R6EMU && insn.r_format.opcode == jr_op)
break;
*contpc = regs->regs[insn.r_format.rs];
return 1;
}