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.
---
This replaces the old 16/28 "Don't call non-existent Soft_emulate_8xx from
SoftwareEmulation".
arch/powerpc/Kconfig | 11 ++
arch/powerpc/kernel/Makefile | 2 +
arch/powerpc/kernel/softemu8xx.c | 202 ++++++++++++++++++++++++++++++++++++++
arch/powerpc/kernel/traps.c | 6 +-
4 files changed, 220 insertions(+), 1 deletions(-)
create mode 100644 arch/powerpc/kernel/softemu8xx.c
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2622f04..0c0329e 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -180,6 +180,17 @@ 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
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 967afc5..0d7b68b 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -76,6 +76,8 @@ obj-$(CONFIG_KEXEC) += machine_kexec.o crash.o
$(kexec-y)
obj-$(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
diff --git a/arch/powerpc/kernel/softemu8xx.c b/arch/powerpc/kernel/softemu8xx.c
new file mode 100644
index 0000000..67d6f68
--- /dev/null
+++ b/arch/powerpc/kernel/softemu8xx.c
@@ -0,0 +1,202 @@
+/*
+ * Software emulation of some PPC instructions for the 8xx core.
+ *
+ * Copyright (C) 1998 Dan Malek ([EMAIL PROTECTED])
+ *
+ * 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 *)¤t->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, ¤t->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;
+}
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index ccfc99d..81859ae 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -898,7 +898,9 @@ 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);
@@ -928,7 +930,7 @@ void SoftwareEmulation(struct pt_regs *regs)
return;
}
-#else
+#elif defined(CONFIG_8XX_MINIMAL_FPEMU)
errcode = Soft_emulate_8xx(regs);
switch (errcode) {
case 0:
@@ -941,6 +943,8 @@ 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 */
--
1.5.3.1
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