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Commit 2ef4dfd9 authored Apr 08, 2016 by Helge Deller

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

parent ef72f311

arch/parisc/include/asm/uaccess.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -77,6 +77,7 @@ 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
	@@ -299,6 +299,7 @@ int main(void)
	#endif		#endif
	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
	@@ -145,6 +145,7 @@ 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;