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linux-next/arch/sparc/lib/ksyms.c
David S. Miller 44922150d8 sparc64: Fix userspace FPU register corruptions.
If we have a series of events from userpsace, with %fprs=FPRS_FEF,
like follows:

ETRAP
	ETRAP
		VIS_ENTRY(fprs=0x4)
		VIS_EXIT
		RTRAP (kernel FPU restore with fpu_saved=0x4)
	RTRAP

We will not restore the user registers that were clobbered by the FPU
using kernel code in the inner-most trap.

Traps allocate FPU save slots in the thread struct, and FPU using
sequences save the "dirty" FPU registers only.

This works at the initial trap level because all of the registers
get recorded into the top-level FPU save area, and we'll return
to userspace with the FPU disabled so that any FPU use by the user
will take an FPU disabled trap wherein we'll load the registers
back up properly.

But this is not how trap returns from kernel to kernel operate.

The simplest fix for this bug is to always save all FPU register state
for anything other than the top-most FPU save area.

Getting rid of the optimized inner-slot FPU saving code ends up
making VISEntryHalf degenerate into plain VISEntry.

Longer term we need to do something smarter to reinstate the partial
save optimizations.  Perhaps the fundament error is having trap entry
and exit allocate FPU save slots and restore register state.  Instead,
the VISEntry et al. calls should be doing that work.

This bug is about two decades old.

Reported-by: James Y Knight <jyknight@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2015-08-06 19:13:25 -07:00

163 lines
4.1 KiB
C

/*
* Export of symbols defined in assembler
*/
/* Tell string.h we don't want memcpy etc. as cpp defines */
#define EXPORT_SYMTAB_STROPS
#include <linux/module.h>
#include <linux/string.h>
#include <linux/types.h>
#include <asm/checksum.h>
#include <asm/uaccess.h>
#include <asm/ftrace.h>
/* string functions */
EXPORT_SYMBOL(strlen);
EXPORT_SYMBOL(strncmp);
/* mem* functions */
extern void *__memscan_zero(void *, size_t);
extern void *__memscan_generic(void *, int, size_t);
extern void *__bzero(void *, size_t);
EXPORT_SYMBOL(memscan);
EXPORT_SYMBOL(__memscan_zero);
EXPORT_SYMBOL(__memscan_generic);
EXPORT_SYMBOL(memcmp);
EXPORT_SYMBOL(memcpy);
EXPORT_SYMBOL(memset);
EXPORT_SYMBOL(memmove);
EXPORT_SYMBOL(__bzero);
/* Networking helper routines. */
EXPORT_SYMBOL(csum_partial);
#ifdef CONFIG_MCOUNT
EXPORT_SYMBOL(_mcount);
#endif
/*
* sparc
*/
#ifdef CONFIG_SPARC32
extern int __ashrdi3(int, int);
extern int __ashldi3(int, int);
extern int __lshrdi3(int, int);
extern int __muldi3(int, int);
extern int __divdi3(int, int);
extern void (*__copy_1page)(void *, const void *);
extern void (*bzero_1page)(void *);
extern void ___rw_read_enter(void);
extern void ___rw_read_try(void);
extern void ___rw_read_exit(void);
extern void ___rw_write_enter(void);
/* Networking helper routines. */
EXPORT_SYMBOL(__csum_partial_copy_sparc_generic);
/* Special internal versions of library functions. */
EXPORT_SYMBOL(__copy_1page);
EXPORT_SYMBOL(__memmove);
EXPORT_SYMBOL(bzero_1page);
/* Moving data to/from/in userspace. */
EXPORT_SYMBOL(__copy_user);
/* Used by asm/spinlock.h */
#ifdef CONFIG_SMP
EXPORT_SYMBOL(___rw_read_enter);
EXPORT_SYMBOL(___rw_read_try);
EXPORT_SYMBOL(___rw_read_exit);
EXPORT_SYMBOL(___rw_write_enter);
#endif
EXPORT_SYMBOL(__ashrdi3);
EXPORT_SYMBOL(__ashldi3);
EXPORT_SYMBOL(__lshrdi3);
EXPORT_SYMBOL(__muldi3);
EXPORT_SYMBOL(__divdi3);
#endif
/*
* sparc64
*/
#ifdef CONFIG_SPARC64
/* Networking helper routines. */
EXPORT_SYMBOL(csum_partial_copy_nocheck);
EXPORT_SYMBOL(__csum_partial_copy_from_user);
EXPORT_SYMBOL(__csum_partial_copy_to_user);
EXPORT_SYMBOL(ip_fast_csum);
/* Moving data to/from/in userspace. */
EXPORT_SYMBOL(___copy_to_user);
EXPORT_SYMBOL(___copy_from_user);
EXPORT_SYMBOL(___copy_in_user);
EXPORT_SYMBOL(__clear_user);
/* Atomic counter implementation. */
#define ATOMIC_OP(op) \
EXPORT_SYMBOL(atomic_##op); \
EXPORT_SYMBOL(atomic64_##op);
#define ATOMIC_OP_RETURN(op) \
EXPORT_SYMBOL(atomic_##op##_return); \
EXPORT_SYMBOL(atomic64_##op##_return);
#define ATOMIC_OPS(op) ATOMIC_OP(op) ATOMIC_OP_RETURN(op)
ATOMIC_OPS(add)
ATOMIC_OPS(sub)
#undef ATOMIC_OPS
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP
EXPORT_SYMBOL(atomic64_dec_if_positive);
/* Atomic bit operations. */
EXPORT_SYMBOL(test_and_set_bit);
EXPORT_SYMBOL(test_and_clear_bit);
EXPORT_SYMBOL(test_and_change_bit);
EXPORT_SYMBOL(set_bit);
EXPORT_SYMBOL(clear_bit);
EXPORT_SYMBOL(change_bit);
/* Special internal versions of library functions. */
EXPORT_SYMBOL(_clear_page);
EXPORT_SYMBOL(clear_user_page);
EXPORT_SYMBOL(copy_user_page);
/* RAID code needs this */
void VISenter(void);
EXPORT_SYMBOL(VISenter);
extern void xor_vis_2(unsigned long, unsigned long *, unsigned long *);
extern void xor_vis_3(unsigned long, unsigned long *, unsigned long *,
unsigned long *);
extern void xor_vis_4(unsigned long, unsigned long *, unsigned long *,
unsigned long *, unsigned long *);
extern void xor_vis_5(unsigned long, unsigned long *, unsigned long *,
unsigned long *, unsigned long *, unsigned long *);
EXPORT_SYMBOL(xor_vis_2);
EXPORT_SYMBOL(xor_vis_3);
EXPORT_SYMBOL(xor_vis_4);
EXPORT_SYMBOL(xor_vis_5);
extern void xor_niagara_2(unsigned long, unsigned long *, unsigned long *);
extern void xor_niagara_3(unsigned long, unsigned long *, unsigned long *,
unsigned long *);
extern void xor_niagara_4(unsigned long, unsigned long *, unsigned long *,
unsigned long *, unsigned long *);
extern void xor_niagara_5(unsigned long, unsigned long *, unsigned long *,
unsigned long *, unsigned long *, unsigned long *);
EXPORT_SYMBOL(xor_niagara_2);
EXPORT_SYMBOL(xor_niagara_3);
EXPORT_SYMBOL(xor_niagara_4);
EXPORT_SYMBOL(xor_niagara_5);
#endif