parisc: Unbreak handling exceptions from kernel modules

[ Upstream commit 2ef4dfd9d9f288943e249b78365a69e3ea3ec072 ]

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
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index a5cb070b54bf4ade7cce44e50f763a5223991e83..df9d8dd72db296ae2ec4d147f3e89d39f10e6926 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 dcd55103a4bb7ff433433c1bcdadc466376de52e..a0dc1e50e3a3ef6fbaa769c90cee856878aa0eba 100644 (file)
--- a/arch/parisc/kernel/asm-offsets.c
+++ b/arch/parisc/kernel/asm-offsets.c
@@ -292,6 +292,7 @@ int main(void)
        DEFINE(ASM_PT_INITIAL, PT_INITIAL);
        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 e5120e653240c4fa52d4895c7d1d206d3d12e68c..50d64a7fc672ccf069cc016a6133186968ca105b 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;