diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2016-12-20 04:30:05 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-04-28 21:02:25 +1000 |
| commit | c4f3b52ce7b16824befb16ab3d045c891b08b7db (patch) | |
| tree | 92f77ba25144dbe046368583e18e21c83015e642 /arch/powerpc/kernel/exceptions-64s.S | |
| parent | a3d96f70c14773d0928c6a54fd278138f0868572 (diff) | |
| download | linux-c4f3b52ce7b16824befb16ab3d045c891b08b7db.tar.bz2 | |
powerpc/64s: Disallow system reset vs system reset reentrancy
In preparation for using a dedicated stack for system reset interrupts,
prevent a nested system reset from recovering, in order to simplify
code that is called in crash/debug path. This allows a system reset
interrupt to just use the base stack pointer.
Keep an in_nmi nesting counter similarly to the in_mce counter. Consider
the interrrupt non-recoverable if it is taken inside another system
reset.
Interrupt nesting could be allowed similarly to MCE, but system reset
is a special case that's not for normal operation, so simplicity wins
until there is requirement for nested system reset interrupts.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 37 |
1 files changed, 32 insertions, 5 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 3a654b1f24e9..4be62568fbc2 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -116,7 +116,11 @@ EXC_VIRT_NONE(0x4000, 0x100) EXC_REAL_BEGIN(system_reset, 0x100, 0x100) SET_SCRATCH0(r13) - EXCEPTION_PROLOG_PSERIES(PACA_EXNMI, system_reset_common, EXC_STD, + /* + * MSR_RI is not enabled, because PACA_EXNMI and nmi stack is + * being used, so a nested NMI exception would corrupt it. + */ + EXCEPTION_PROLOG_PSERIES_NORI(PACA_EXNMI, system_reset_common, EXC_STD, IDLETEST, 0x100) EXC_REAL_END(system_reset, 0x100, 0x100) @@ -128,9 +132,31 @@ EXC_COMMON_BEGIN(system_reset_idle_common) #endif EXC_COMMON_BEGIN(system_reset_common) + /* + * Increment paca->in_nmi then enable MSR_RI. SLB or MCE will be able + * to recover, but nested NMI will notice in_nmi and not recover + * because of the use of the NMI stack. in_nmi reentrancy is tested in + * system_reset_exception. + */ + lhz r10,PACA_IN_NMI(r13) + addi r10,r10,1 + sth r10,PACA_IN_NMI(r13) + li r10,MSR_RI + mtmsrd r10,1 + EXCEPTION_COMMON(PACA_EXNMI, 0x100, - system_reset, system_reset_exception, - ret_from_except, ADD_NVGPRS;ADD_RECONCILE) + system_reset, system_reset_exception, 1f, + ADD_NVGPRS;ADD_RECONCILE) +1: /* EXCEPTION_COMMON continues here */ + + /* + * The stack is no longer in use, decrement in_nmi. + */ + lhz r10,PACA_IN_NMI(r13) + subi r10,r10,1 + sth r10,PACA_IN_NMI(r13) + + b ret_from_except #ifdef CONFIG_PPC_PSERIES /* @@ -138,8 +164,9 @@ EXC_COMMON_BEGIN(system_reset_common) */ TRAMP_REAL_BEGIN(system_reset_fwnmi) SET_SCRATCH0(r13) /* save r13 */ - EXCEPTION_PROLOG_PSERIES(PACA_EXNMI, system_reset_common, EXC_STD, - NOTEST, 0x100) + /* See comment at system_reset exception */ + EXCEPTION_PROLOG_PSERIES_NORI(PACA_EXNMI, system_reset_common, + EXC_STD, NOTEST, 0x100) #endif /* CONFIG_PPC_PSERIES */ |