Commit 5dd57a13 authored by Scott Wood's avatar Scott Wood Committed by Kumar Gala
Browse files

[POWERPC] 8xx: Move softemu8xx.c from arch/ppc 



Previously, Soft_emulate_8xx was called with no implementation, resulting in
build failures whenever building 8xx without math emulation.  The
implementation is copied from arch/ppc to resolve this issue.

However, this sort of minimal emulation is not a very good idea other than
for compatibility with existing userspaces, as it's less efficient than
soft-float and can mislead users into believing they have soft-float.  Thus,
it is made a configurable option, off by default.

Signed-off-by: default avatarScott Wood <scottwood@freescale.com>
Signed-off-by: default avatarKumar Gala <galak@kernel.crashing.org>
parent c4e05bc5

arch/powerpc/Kconfig

+11 −0
Original line number Diff line number Diff line
@@ -198,6 +198,17 @@ config MATH_EMULATION 
	  unit, which will allow programs that use floating-point

	  instructions to run.



config 8XX_MINIMAL_FPEMU

	bool "Minimal math emulation for 8xx"

	depends on 8xx && !MATH_EMULATION

	help

	  Older arch/ppc kernels still emulated a few floating point

	  instructions such as load and store, even when full math

	  emulation is disabled.  Say "Y" here if you want to preserve

	  this behavior.



	  It is recommended that you build a soft-float userspace instead.



config IOMMU_VMERGE

	bool "Enable IOMMU virtual merging"

	depends on PPC64

arch/powerpc/kernel/Makefile

+2 −0
Original line number Diff line number Diff line
@@ -75,6 +75,8 @@ obj-$(CONFIG_KEXEC) += machine_kexec.o crash.o \ 
obj-$(CONFIG_AUDIT)		+= audit.o

obj64-$(CONFIG_AUDIT)		+= compat_audit.o



obj-$(CONFIG_8XX_MINIMAL_FPEMU) += softemu8xx.o



ifneq ($(CONFIG_PPC_INDIRECT_IO),y)

obj-y				+= iomap.o

endif

arch/powerpc/kernel/softemu8xx.c

0 → 100644
+202 −0
Original line number Diff line number Diff line 
/*

 * Software emulation of some PPC instructions for the 8xx core.

 *

 * Copyright (C) 1998 Dan Malek (dmalek@jlc.net)

 *

 * Software floating emuation for the MPC8xx processor.  I did this mostly

 * because it was easier than trying to get the libraries compiled for

 * software floating point.  The goal is still to get the libraries done,

 * but I lost patience and needed some hacks to at least get init and

 * shells running.  The first problem is the setjmp/longjmp that save

 * and restore the floating point registers.

 *

 * For this emulation, our working registers are found on the register

 * save area.

 */



#include <linux/errno.h>

#include <linux/sched.h>

#include <linux/kernel.h>

#include <linux/mm.h>

#include <linux/stddef.h>

#include <linux/unistd.h>

#include <linux/ptrace.h>

#include <linux/slab.h>

#include <linux/user.h>

#include <linux/a.out.h>

#include <linux/interrupt.h>



#include <asm/pgtable.h>

#include <asm/uaccess.h>

#include <asm/system.h>

#include <asm/io.h>



/* Eventually we may need a look-up table, but this works for now.

*/

#define LFS	48

#define LFD	50

#define LFDU	51

#define STFD	54

#define STFDU	55

#define FMR	63



void print_8xx_pte(struct mm_struct *mm, unsigned long addr)

{

	pgd_t *pgd;

	pmd_t *pmd;

	pte_t *pte;



	printk(" pte @ 0x%8lx: ", addr);

	pgd = pgd_offset(mm, addr & PAGE_MASK);

	if (pgd) {

		pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),

		                 addr & PAGE_MASK);

		if (pmd && pmd_present(*pmd)) {

			pte = pte_offset_kernel(pmd, addr & PAGE_MASK);

			if (pte) {

				printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n",

				        (long)pgd, (long)pte, (long)pte_val(*pte));

#define pp ((long)pte_val(*pte))

				printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx "

				       "CI: %lx v: %lx\n",

				       pp>>12,    /* rpn */

				       (pp>>10)&3, /* pp */

				       (pp>>3)&1, /* small */

				       (pp>>2)&1, /* shared */

				       (pp>>1)&1, /* cache inhibit */

				       pp&1       /* valid */

				       );

#undef pp

			}

			else {

				printk("no pte\n");

			}

		}

		else {

			printk("no pmd\n");

		}

	}

	else {

		printk("no pgd\n");

	}

}



int get_8xx_pte(struct mm_struct *mm, unsigned long addr)

{

	pgd_t *pgd;

	pmd_t *pmd;

	pte_t *pte;

	int retval = 0;



	pgd = pgd_offset(mm, addr & PAGE_MASK);

	if (pgd) {

		pmd = pmd_offset(pud_offset(pgd, addr & PAGE_MASK),

		                 addr & PAGE_MASK);

		if (pmd && pmd_present(*pmd)) {

			pte = pte_offset_kernel(pmd, addr & PAGE_MASK);

			if (pte) {

				retval = (int)pte_val(*pte);

			}

		}

	}

	return retval;

}



/*

 * We return 0 on success, 1 on unimplemented instruction, and EFAULT

 * if a load/store faulted.

 */

int Soft_emulate_8xx(struct pt_regs *regs)

{

	u32 inst, instword;

	u32 flreg, idxreg, disp;

	int retval;

	s16 sdisp;

	u32 *ea, *ip;



	retval = 0;



	instword = *((u32 *)regs->nip);

	inst = instword >> 26;



	flreg = (instword >> 21) & 0x1f;

	idxreg = (instword >> 16) & 0x1f;

	disp = instword & 0xffff;



	ea = (u32 *)(regs->gpr[idxreg] + disp);

	ip = (u32 *)&current->thread.fpr[flreg];



	switch ( inst )

	{

	case LFD:

		/* this is a 16 bit quantity that is sign extended

		 * so use a signed short here -- Cort

		 */

		sdisp = (instword & 0xffff);

		ea = (u32 *)(regs->gpr[idxreg] + sdisp);

		if (copy_from_user(ip, ea, sizeof(double)))

			retval = -EFAULT;

		break;



	case LFDU:

		if (copy_from_user(ip, ea, sizeof(double)))

			retval = -EFAULT;

		else

			regs->gpr[idxreg] = (u32)ea;

		break;

	case LFS:

		sdisp = (instword & 0xffff);

		ea = (u32 *)(regs->gpr[idxreg] + sdisp);

		if (copy_from_user(ip, ea, sizeof(float)))

			retval = -EFAULT;

		break;

	case STFD:

		/* this is a 16 bit quantity that is sign extended

		 * so use a signed short here -- Cort

		 */

		sdisp = (instword & 0xffff);

		ea = (u32 *)(regs->gpr[idxreg] + sdisp);

		if (copy_to_user(ea, ip, sizeof(double)))

			retval = -EFAULT;

		break;



	case STFDU:

		if (copy_to_user(ea, ip, sizeof(double)))

			retval = -EFAULT;

		else

			regs->gpr[idxreg] = (u32)ea;

		break;

	case FMR:

		/* assume this is a fp move -- Cort */

		memcpy(ip, &current->thread.fpr[(instword>>11)&0x1f],

		       sizeof(double));

		break;

	default:

		retval = 1;

		printk("Bad emulation %s/%d\n"

		       " NIP: %08lx instruction: %08x opcode: %x "

		       "A: %x B: %x C: %x code: %x rc: %x\n",

		       current->comm,current->pid,

		       regs->nip,

		       instword,inst,

		       (instword>>16)&0x1f,

		       (instword>>11)&0x1f,

		       (instword>>6)&0x1f,

		       (instword>>1)&0x3ff,

		       instword&1);

		{

			int pa;

			print_8xx_pte(current->mm,regs->nip);

			pa = get_8xx_pte(current->mm,regs->nip) & PAGE_MASK;

			pa |= (regs->nip & ~PAGE_MASK);

			pa = (unsigned long)__va(pa);

			printk("Kernel VA for NIP %x ", pa);

			print_8xx_pte(current->mm,pa);

		}

	}



	if (retval == 0)

		regs->nip += 4;



	return retval;

}

arch/powerpc/kernel/traps.c

+5 −1
Original line number Diff line number Diff line
@@ -906,7 +906,9 @@ void SoftwareEmulation(struct pt_regs *regs) 
{

	extern int do_mathemu(struct pt_regs *);

	extern int Soft_emulate_8xx(struct pt_regs *);

#if defined(CONFIG_MATH_EMULATION) || defined(CONFIG_8XX_MINIMAL_FPEMU)

	int errcode;

#endif



	CHECK_FULL_REGS(regs);
@@ -936,7 +938,7 @@ void SoftwareEmulation(struct pt_regs *regs) 
		return;

	}



#else

#elif defined(CONFIG_8XX_MINIMAL_FPEMU)

	errcode = Soft_emulate_8xx(regs);

	switch (errcode) {

	case 0:
@@ -949,6 +951,8 @@ void SoftwareEmulation(struct pt_regs *regs) 
		_exception(SIGSEGV, regs, SEGV_MAPERR, regs->nip);

		return;

	}

#else

	_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);

#endif

}

#endif /* CONFIG_8xx */

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