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Commit 61a92f70 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc: Add support for relative exception tables 



This halves the exception table size on 64-bit builds, and it allows
build-time sorting of exception tables to work on relocated kernels.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
[mpe: Minor asm fixups and bits to keep the selftests working]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 24bfa6a9

arch/powerpc/include/asm/ppc_asm.h

+3 −3
Original line number Diff line number Diff line
@@ -785,9 +785,9 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601) 
 */

#define EX_TABLE(_fault, _target)		\

	stringify_in_c(.section __ex_table,"a";)\

	PPC_LONG_ALIGN stringify_in_c(;)	\

	PPC_LONG stringify_in_c(_fault;)	\

	PPC_LONG stringify_in_c(_target;)	\

	stringify_in_c(.balign 4;)		\

	stringify_in_c(.long (_fault) - . ;)	\

	stringify_in_c(.long (_target) - . ;)	\

	stringify_in_c(.previous)



#endif /* _ASM_POWERPC_PPC_ASM_H */

arch/powerpc/include/asm/uaccess.h

+17 −10
Original line number Diff line number Diff line
@@ -64,23 +64,30 @@ 
	 __access_ok((__force unsigned long)(addr), (size), get_fs()))



/*

 * The exception table consists of pairs of addresses: the first is the

 * address of an instruction that is allowed to fault, and the second is

 * The exception table consists of pairs of relative addresses: the first is

 * the address of an instruction that is allowed to fault, and the second is

 * the address at which the program should continue.  No registers are

 * modified, so it is entirely up to the continuation code to figure out

 * what to do.

 * modified, so it is entirely up to the continuation code to figure out what

 * to do.

 *

 * All the routines below use bits of fixup code that are out of line

 * with the main instruction path.  This means when everything is well,

 * we don't even have to jump over them.  Further, they do not intrude

 * on our cache or tlb entries.

 * All the routines below use bits of fixup code that are out of line with the

 * main instruction path.  This means when everything is well, we don't even

 * have to jump over them.  Further, they do not intrude on our cache or tlb

 * entries.

 */



#define ARCH_HAS_RELATIVE_EXTABLE



struct exception_table_entry {

	unsigned long insn;

	unsigned long fixup;

	int insn;

	int fixup;

};



static inline unsigned long extable_fixup(const struct exception_table_entry *x)

{

	return (unsigned long)&x->fixup + x->fixup;

}



/*

 * These are the main single-value transfer routines.  They automatically

 * use the right size if we just have the right pointer type.

arch/powerpc/kernel/kprobes.c

+1 −1
Original line number Diff line number Diff line
@@ -449,7 +449,7 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) 
		 * zero, try to fix up.

		 */

		if ((entry = search_exception_tables(regs->nip)) != NULL) {

			regs->nip = entry->fixup;

			regs->nip = extable_fixup(entry);

			return 1;

		}

arch/powerpc/kernel/traps.c

+1 −1
Original line number Diff line number Diff line
@@ -365,7 +365,7 @@ static inline int check_io_access(struct pt_regs *regs) 
			       (*nip & 0x100)? "OUT to": "IN from",

			       regs->gpr[rb] - _IO_BASE, nip);

			regs->msr |= MSR_RI;

			regs->nip = entry->fixup;

			regs->nip = extable_fixup(entry);

			return 1;

		}

	}

arch/powerpc/mm/fault.c

+1 −1
Original line number Diff line number Diff line
@@ -512,7 +512,7 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) 


	/* Are we prepared to handle this fault?  */

	if ((entry = search_exception_tables(regs->nip)) != NULL) {

		regs->nip = entry->fixup;

		regs->nip = extable_fixup(entry);

		return;

	}