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parisc: Unbreak handling exceptions from kernel modules

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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;