> > >> So, it seems that handling exceptions from modules never worked on
> > >> pa-risc, it was just masked by the fact that exceptions from modules don't
> > >> happen during normal use.
> >
> > Sadly you seem to be right :-(
> > I did more testing with the test_user_copy module (with vanilla kernel 4.5 and without the relative extable support).
>
> The attached patch fixes the exception handling for modules for me.
> This is realized by saving the %r27 register in the fault handler and restoring it in the exception path.
> With this patch the "test_user_copy" kernel module succeeds when loaded.
> Mikulas, can you try it with your testcases ?
Attached patch additionally adds support for resolving R_PARISC_PCREL32 relocations,
which fixes the 32bit extable change which was introduced with kernel 4.6-rc1.
With that I think we have all module issues resolved ?
Helge
diff --git a/arch/parisc/include/asm/uaccess.h b/arch/parisc/include/asm/uaccess.h
index d4dd6e5..b370d61 100644
--- a/arch/parisc/include/asm/uaccess.h
+++ b/arch/parisc/include/asm/uaccess.h
@@ -79,6 +79,7 @@ struct exception_data {
unsigned long fault_ip;
unsigned long fault_space;
unsigned long fault_addr;
+ unsigned long fault_gp;
};
#define __get_user(x, ptr) \
diff --git a/arch/parisc/kernel/asm-offsets.c b/arch/parisc/kernel/asm-offsets.c
index d2f6257..137c91e 100644
--- a/arch/parisc/kernel/asm-offsets.c
+++ b/arch/parisc/kernel/asm-offsets.c
@@ -301,6 +301,7 @@ int main(void)
DEFINE(EXCDATA_IP, offsetof(struct exception_data, fault_ip));
DEFINE(EXCDATA_SPACE, offsetof(struct exception_data, fault_space));
DEFINE(EXCDATA_ADDR, offsetof(struct exception_data, fault_addr));
+ DEFINE(EXCDATA_GP, offsetof(struct exception_data, fault_gp));
BLANK();
DEFINE(ASM_PDC_RESULT_SIZE, NUM_PDC_RESULT * sizeof(unsigned long));
BLANK();
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index b9d75d9..c54cf39 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -788,6 +788,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs,
CHECK_RELOC(val, 22);
*loc = (*loc & ~0x3ff1ffd) | reassemble_22(val);
break;
+ case R_PARISC_PCREL32:
+ /* 32-bit PC relative address */
+ *loc = val - dot - 8 + addend;
+ break;
case R_PARISC_DIR64:
/* 64-bit effective address */
*loc64 = val + addend;
diff --git a/arch/parisc/kernel/parisc_ksyms.c b/arch/parisc/kernel/parisc_ksyms.c
index 568b2c6..3cad8aa 100644
--- a/arch/parisc/kernel/parisc_ksyms.c
+++ b/arch/parisc/kernel/parisc_ksyms.c
@@ -47,11 +47,11 @@ EXPORT_SYMBOL(__cmpxchg_u64);
EXPORT_SYMBOL(lclear_user);
EXPORT_SYMBOL(lstrnlen_user);
-/* Global fixups */
-extern void fixup_get_user_skip_1(void);
-extern void fixup_get_user_skip_2(void);
-extern void fixup_put_user_skip_1(void);
-extern void fixup_put_user_skip_2(void);
+/* Global fixups - defined as int to avoid creation of function pointers */
+extern int fixup_get_user_skip_1;
+extern int fixup_get_user_skip_2;
+extern int fixup_put_user_skip_1;
+extern int fixup_put_user_skip_2;
EXPORT_SYMBOL(fixup_get_user_skip_1);
EXPORT_SYMBOL(fixup_get_user_skip_2);
EXPORT_SYMBOL(fixup_put_user_skip_1);
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c
index 16e0735..97d6b20 100644
--- a/arch/parisc/kernel/traps.c
+++ b/arch/parisc/kernel/traps.c
@@ -795,6 +795,9 @@ void notrace handle_interruption(int code, struct pt_regs *regs)
if (fault_space == 0 && !faulthandler_disabled())
{
+ /* Clean up and return if in exception table. */
+ if (fixup_exception(regs))
+ return;
pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC);
parisc_terminate("Kernel Fault", regs, code, fault_address);
}
diff --git a/arch/parisc/lib/fixup.S b/arch/parisc/lib/fixup.S
index 536ef66..1052b74 100644
--- 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 26fac9c..7a6ecaa 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -147,6 +147,7 @@ int fixup_exception(struct pt_regs *regs)
d->fault_ip = regs->iaoq[0];
d->fault_space = regs->isr;
d->fault_addr = regs->ior;
+ d->fault_gp = regs->gr[27];
regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
regs->iaoq[0] &= ~3;
