| Message ID | d0f55ba3b94de5c1bb7c93cbadb9829fa6889fed.1504281896.git.joabreu@synopsys.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v3] arc: Re-enable MMU upon a Machine Check exception | expand |
Hi Jose, Some very minor nit picks to keep in mind for future patches. 1. all arc patches start with uppercase ARC: On 09/01/2017 09:05 AM, Jose Abreu wrote: > I recently came upon a scenario where I would get a double fault > after a machine check error. It turns out that for Ksymbol lookup > to work with modules we need to have MMU enabled because module > address is mapped in the cached space. > > This patch re-enables the MMU before calling die() so that > stacktracing of modules work when a machine check exception happens. > > Signed-off-by: Jose Abreu <joabreu@synopsys.com> > Cc: Vineet Gupta <vgupta@synopsys.com> > Cc: Alexey Brodkin <abrodkin@synopsys.com> > > Changes from v2: > - Rephrased commit title and description > Changes from v1: > - Moved MMU re-enable to machine check exception handler > --- 2. The patch revision history needs to be added *after* the line with ---, that way git am automatically strips them off when patch is applied. -Vineet
diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c index ff83e78..d92f161 100644 --- a/arch/arc/kernel/traps.c +++ b/arch/arc/kernel/traps.c @@ -19,6 +19,8 @@ #include <linux/ptrace.h> #include <linux/kprobes.h> #include <linux/kgdb.h> +#include <asm/arcregs.h> +#include <asm/mmu.h> #include <asm/setup.h> #include <asm/unaligned.h> #include <asm/kprobes.h> @@ -103,6 +105,9 @@ int do_misaligned_access(unsigned long address, struct pt_regs *regs, */ void do_machine_check_fault(unsigned long address, struct pt_regs *regs) { + /* MMU must be enabled for Ksymbol lookup in modules */ + write_aux_reg(ARC_REG_PID, MMU_ENABLE | read_aux_reg(ARC_REG_PID)); + die("Machine Check Exception", regs, address); }
I recently came upon a scenario where I would get a double fault after a machine check error. It turns out that for Ksymbol lookup to work with modules we need to have MMU enabled because module address is mapped in the cached space. This patch re-enables the MMU before calling die() so that stacktracing of modules work when a machine check exception happens. Signed-off-by: Jose Abreu <joabreu@synopsys.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Alexey Brodkin <abrodkin@synopsys.com> Changes from v2: - Rephrased commit title and description Changes from v1: - Moved MMU re-enable to machine check exception handler --- arch/arc/kernel/traps.c | 5 +++++ 1 file changed, 5 insertions(+)