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No actual hardware supported by FreeBSD requires this SPRG save/restore

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paranoia, so kill it. In particular, changes to SPRG0 are dangerous, since
that is where the PCPU pointer is kept.
This commit is contained in:
Nathan Whitehorn 2013-12-01 19:45:04 +00:00
parent c1cb22d755
commit ff4ae2ead1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=258808
1 changed files with 1 additions and 52 deletions
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53
sys/powerpc/ofw/ofw_machdep.c
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@ -91,52 +91,6 @@ ofw_restore_trap_vec(char *restore_trap_vec)
__syncicache(EXC_RSVD, EXC_LAST - EXC_RSVD);
}
/*
* Saved SPRG0-3 from OpenFirmware. Will be restored prior to the callback.
*/
register_t ofw_sprg0_save;
static __inline void
ofw_sprg_prepare(void)
{
if (ofw_real_mode)
return;
/*
* Assume that interrupt are disabled at this point, or
* SPRG1-3 could be trashed
*/
__asm __volatile("mfsprg0 %0\n\t"
"mtsprg0 %1\n\t"
"mtsprg1 %2\n\t"
"mtsprg2 %3\n\t"
"mtsprg3 %4\n\t"
: "=&r"(ofw_sprg0_save)
: "r"(ofmsr[1]),
"r"(ofmsr[2]),
"r"(ofmsr[3]),
"r"(ofmsr[4]));
}
static __inline void
ofw_sprg_restore(void)
{
#if 0
if (ofw_real_mode)
return;
#endif
/*
* Note that SPRG1-3 contents are irrelevant. They are scratch
* registers used in the early portion of trap handling when
* interrupts are disabled.
*
* PCPU data cannot be used until this routine is called !
*/
__asm __volatile("mtsprg0 %0" :: "r"(ofw_sprg0_save));
}
#endif
static int
parse_ofw_memory(phandle_t node, const char *prop, struct mem_region *output)
{
@ -332,13 +286,10 @@ openfirmware_core(void *args)
/*
* Turn off exceptions - we really don't want to end up
* anywhere unexpected with PCPU set to something strange
* or the stack pointer wrong.
* anywhere in the kernel while in OF state.
*/
oldmsr = intr_disable();
ofw_sprg_prepare();
/* Save trap vectors */
ofw_save_trap_vec(save_trap_of);
@ -360,8 +311,6 @@ openfirmware_core(void *args)
/* Restore trap vecotrs */
ofw_restore_trap_vec(save_trap_of);
ofw_sprg_restore();
intr_restore(oldmsr);
return (result);