4.16-stable review patch. If anyone has any objections, please let me know.
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From: Anshuman Khandual khandual@linux.vnet.ibm.com
[ Upstream commit 709b973c844c0b4d115ac3a227a2e5a68722c912 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kernel/traps.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-)
--- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1612,6 +1612,22 @@ void facility_unavailable_exception(stru value = mfspr(SPRN_FSCR);
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) { /* * User is accessing the DSCR register using the problem @@ -1678,25 +1694,11 @@ void facility_unavailable_exception(stru 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", hv ? "Hypervisor " : "", facility, status, regs->nip, regs->msr);
out: - if (user_mode(regs)) { - _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); - return; - } - - die("Unexpected facility unavailable exception", regs, SIGABRT); + _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); } #endif