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Commit 9bd5af84 authored Apr 08, 2016 by Helge Deller Committed by Sasha Levin Apr 20, 2016

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>

parent e69ea046

arch/parisc/include/asm/uaccess.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -76,6 +76,7 @@ struct exception_table_entry {
	*/		*/
	struct exception_data {		struct exception_data {
	unsigned long fault_ip;		unsigned long fault_ip;
			unsigned long fault_gp;
	unsigned long fault_space;		unsigned long fault_space;
	unsigned long fault_addr;		unsigned long fault_addr;
	};		};

arch/parisc/kernel/asm-offsets.c

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -292,6 +292,7 @@ int main(void)
	DEFINE(ASM_PT_INITIAL, PT_INITIAL);		DEFINE(ASM_PT_INITIAL, PT_INITIAL);
	BLANK();		BLANK();
	DEFINE(EXCDATA_IP, offsetof(struct exception_data, fault_ip));		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_SPACE, offsetof(struct exception_data, fault_space));
	DEFINE(EXCDATA_ADDR, offsetof(struct exception_data, fault_addr));		DEFINE(EXCDATA_ADDR, offsetof(struct exception_data, fault_addr));
	BLANK();		BLANK();

arch/parisc/lib/fixup.S

+6 −0

Original line number	Original line	Diff line number	Diff line
	@@ -26,6 +26,7 @@

	#ifdef CONFIG_SMP		#ifdef CONFIG_SMP
	.macro get_fault_ip t1 t2		.macro get_fault_ip t1 t2
			loadgp
	addil LT%__per_cpu_offset,%r27		addil LT%__per_cpu_offset,%r27
	LDREG RT%__per_cpu_offset(%r1),\t1		LDREG RT%__per_cpu_offset(%r1),\t1
	/* t2 = smp_processor_id() */		/* t2 = smp_processor_id() */
	@@ -40,14 +41,19 @@
	LDREG RT%exception_data(%r1),\t1		LDREG RT%exception_data(%r1),\t1
	/* t1 = this_cpu_ptr(&exception_data) */		/* t1 = this_cpu_ptr(&exception_data) */
	add,l \t1,\t2,\t1		add,l \t1,\t2,\t1
			/* %r27 = t1->fault_gp - restore gp */
			LDREG EXCDATA_GP(\t1), %r27
	/* t1 = t1->fault_ip */		/* t1 = t1->fault_ip */
	LDREG EXCDATA_IP(\t1), \t1		LDREG EXCDATA_IP(\t1), \t1
	.endm		.endm
	#else		#else
	.macro get_fault_ip t1 t2		.macro get_fault_ip t1 t2
			loadgp
	/* t1 = this_cpu_ptr(&exception_data) */		/* t1 = this_cpu_ptr(&exception_data) */
	addil LT%exception_data,%r27		addil LT%exception_data,%r27
	LDREG RT%exception_data(%r1),\t2		LDREG RT%exception_data(%r1),\t2
			/* %r27 = t2->fault_gp - restore gp */
			LDREG EXCDATA_GP(\t2), %r27
	/* t1 = t2->fault_ip */		/* t1 = t2->fault_ip */
	LDREG EXCDATA_IP(\t2), \t1		LDREG EXCDATA_IP(\t2), \t1
	.endm		.endm

arch/parisc/mm/fault.c

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -151,6 +151,7 @@ int fixup_exception(struct pt_regs *regs)
	struct exception_data *d;		struct exception_data *d;
	d = this_cpu_ptr(&exception_data);		d = this_cpu_ptr(&exception_data);
	d->fault_ip = regs->iaoq[0];		d->fault_ip = regs->iaoq[0];
			d->fault_gp = regs->gr[27];
	d->fault_space = regs->isr;		d->fault_space = regs->isr;
	d->fault_addr = regs->ior;		d->fault_addr = regs->ior;