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

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index d4dd6e58682ce582f9b6581095fb11e59dee2766..6f893d29f1b21625aadc4464d06ffba30b7697f3 100644 (file)
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -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;
 };

diff --git a/arch/parisc/kernel/asm-offsets.c b/arch/parisc/kernel/asm-offsets.c
index d2f62570a7b16d4f4c6321515d980f048cd278f2..78d30d2ea2d8bb24116a7639a3d4bc5f90400058 100644 (file)
--- a/arch/parisc/kernel/asm-offsets.c
+++ b/arch/parisc/kernel/asm-offsets.c
@@ -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();

diff --git a/arch/parisc/lib/fixup.S b/arch/parisc/lib/fixup.S
index 536ef66bb94b5aa8c46800a968514184b5e2d85d..1052b747e011336621c6ca9f7c9eaf78af7af6df 100644 (file)
--- a/arch/parisc/lib/fixup.S
+++ b/arch/parisc/lib/fixup.S
@@ -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

diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 26fac9c671c9375ab9ae1663617c237186f55aba..16dbe81c97c9005df3cbb91045ccb6ed20878930 100644 (file)
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -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;