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parisc: Unbreak handling exceptions from kernel modules 

Handling exceptions from modules never worked on parisc.
It was just masked by the fact that exceptions from modules
don't happen during normal use.

When a module triggers an exception in get_user() we need to load the
main kernel dp value before accessing the exception_data structure, and
afterwards restore the original dp value of the module on exit.

Noticed-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@vger.kernel.org
This commit is contained in:
Helge Deller 2016-04-08 18:32:52 +02:00
parent ef72f3110d
commit 2ef4dfd9d9
4 changed files with 9 additions and 0 deletions
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1
arch/parisc/include/asm/uaccess.h
View File

@ -77,6 +77,7 @@ struct exception_table_entry {
*/
struct exception_data {
unsigned long fault_ip;
unsigned long fault_gp;
unsigned long fault_space;
unsigned long fault_addr;
};

1
arch/parisc/kernel/asm-offsets.c
View File

@ -299,6 +299,7 @@ int main(void)
#endif
BLANK();
DEFINE(EXCDATA_IP, offsetof(struct exception_data, fault_ip));
DEFINE(EXCDATA_GP, offsetof(struct exception_data, fault_gp));
DEFINE(EXCDATA_SPACE, offsetof(struct exception_data, fault_space));
DEFINE(EXCDATA_ADDR, offsetof(struct exception_data, fault_addr));
BLANK();

6
arch/parisc/lib/fixup.S
View File

@ -26,6 +26,7 @@
#ifdef CONFIG_SMP
.macro get_fault_ip t1 t2
loadgp
addil LT%__per_cpu_offset,%r27
LDREG RT%__per_cpu_offset(%r1),\t1
/* t2 = smp_processor_id() */
@ -40,14 +41,19 @@
LDREG RT%exception_data(%r1),\t1
/* t1 = this_cpu_ptr(&exception_data) */
add,l \t1,\t2,\t1
/* %r27 = t1->fault_gp - restore gp */
LDREG EXCDATA_GP(\t1), %r27
/* t1 = t1->fault_ip */
LDREG EXCDATA_IP(\t1), \t1
.endm
#else
.macro get_fault_ip t1 t2
loadgp
/* t1 = this_cpu_ptr(&exception_data) */
addil LT%exception_data,%r27
LDREG RT%exception_data(%r1),\t2
/* %r27 = t2->fault_gp - restore gp */
LDREG EXCDATA_GP(\t2), %r27
/* t1 = t2->fault_ip */
LDREG EXCDATA_IP(\t2), \t1
.endm

1
arch/parisc/mm/fault.c
View File

@ -145,6 +145,7 @@ int fixup_exception(struct pt_regs *regs)
struct exception_data *d;
d = this_cpu_ptr(&exception_data);
d->fault_ip = regs->iaoq[0];
d->fault_gp = regs->gr[27];
d->fault_space = regs->isr;
d->fault_addr = regs->ior;