parisc: Unbreak handling exceptions from kernel modules

commit 2ef4dfd9d9f288943e249b78365a69e3ea3ec072 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index 0abdd4c607ed9dc22dce8610d8f8d1d016656553..1960b87c1c8becb9796babc5c77e4452472b6e37 100644 (file)
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -76,6 +76,7 @@ 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 a762864ec92e9baf9bf2d2016474c21b94e026b8..f9064449908aad5ae01fbeb1c92e97399b0b828b 100644 (file)
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -151,6 +151,7 @@ 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;