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powerpc/fscr: Enable interrupts earlier before calling get_user()

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The function get_user() can sleep while trying to fetch instruction
from user address space and causes the following warning from the
scheduler.

BUG: sleeping function called from invalid context

Though interrupts get enabled back but it happens bit later after
get_user() is called. This change moves enabling these interrupts
earlier covering the function get_user(). While at this, lets check
for kernel mode and crash as this interrupt should not have been
triggered from the kernel context.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Anshuman Khandual 2018-03-29 11:53:37 +05:30 • committed by Michael Ellerman
parent 501a78cbc1
commit 709b973c84
1 changed files with 17 additions and 15 deletions
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32
arch/powerpc/kernel/traps.c
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@ -1613,6 +1613,22 @@ void facility_unavailable_exception(struct pt_regs *regs)
value = mfspr(SPRN_FSCR); value = mfspr(SPRN_FSCR);
status = value >> 56; status = value >> 56;
if ((hv || status >= 2) &&
(status < ARRAY_SIZE(facility_strings)) &&
facility_strings[status])
facility = facility_strings[status];
/* We should not have taken this interrupt in kernel */
if (!user_mode(regs)) {
pr_emerg("Facility '%s' unavailable (%d) exception in kernel mode at %lx\n",
facility, status, regs->nip);
die("Unexpected facility unavailable exception", regs, SIGABRT);
}
/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
if (status == FSCR_DSCR_LG) { if (status == FSCR_DSCR_LG) {
/* /*
* User is accessing the DSCR register using the problem * User is accessing the DSCR register using the problem
@ -1679,25 +1695,11 @@ void facility_unavailable_exception(struct pt_regs *regs)
return; return;
} }
if ((hv || status >= 2) &&
(status < ARRAY_SIZE(facility_strings)) &&
facility_strings[status])
facility = facility_strings[status];
/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at 0x%lx, MSR=%lx\n", pr_err_ratelimited("%sFacility '%s' unavailable (%d), exception at 0x%lx, MSR=%lx\n",
hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr); hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr);
out: out:
if (user_mode(regs)) { _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
_exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
return;
}
die("Unexpected facility unavailable exception", regs, SIGABRT);
} }
#endif #endif