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powerpc: Add support for relative exception tables

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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: Nicholas Piggin <npiggin@gmail.com>
[mpe: Minor asm fixups and bits to keep the selftests working]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2016-10-14 16:47:31 +11:00 • committed by Michael Ellerman
parent 24bfa6a9e0
commit 61a92f7031
9 changed files with 34 additions and 23 deletions
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27
arch/powerpc/include/asm/uaccess.h
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@ -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.