linux/arch/mips/lib/uncached.c
Kees Cook b847bd64ea MIPS: Only use current_stack_pointer on GCC
Unfortunately, Clang did not have support for "sp" as a global register
definition, and was crashing after the addition of current_stack_pointer.
This has been fixed in Clang 14, but earlier Clang versions need to
avoid this code, so add a versioned test and revert back to the
open-coded asm instances. Fixes Clang build error:

fatal error: error in backend: Invalid register name global variable

Fixes: 200ed341b8 ("mips: Implement "current_stack_pointer"")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Link: https://lore.kernel.org/lkml/YikTQRql+il3HbrK@dev-arch.thelio-3990X
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Yanteng Si <siyanteng01@gmail.com>
Cc: linux-mips@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
2022-03-14 15:02:53 +01:00

83 lines
2.1 KiB
C

/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2005 Thiemo Seufer
* Copyright (C) 2005 MIPS Technologies, Inc. All rights reserved.
* Author: Maciej W. Rozycki <macro@mips.com>
*/
#include <asm/addrspace.h>
#include <asm/bug.h>
#include <asm/cacheflush.h>
#ifndef CKSEG2
#define CKSEG2 CKSSEG
#endif
#ifndef TO_PHYS_MASK
#define TO_PHYS_MASK -1
#endif
/*
* FUNC is executed in one of the uncached segments, depending on its
* original address as follows:
*
* 1. If the original address is in CKSEG0 or CKSEG1, then the uncached
* segment used is CKSEG1.
* 2. If the original address is in XKPHYS, then the uncached segment
* used is XKPHYS(2).
* 3. Otherwise it's a bug.
*
* The same remapping is done with the stack pointer. Stack handling
* works because we don't handle stack arguments or more complex return
* values, so we can avoid sharing the same stack area between a cached
* and the uncached mode.
*/
unsigned long run_uncached(void *func)
{
register long ret __asm__("$2");
long lfunc = (long)func, ufunc;
long usp;
long sp;
__asm__("move %0, $sp" : "=r" (sp));
if (sp >= (long)CKSEG0 && sp < (long)CKSEG2)
usp = CKSEG1ADDR(sp);
#ifdef CONFIG_64BIT
else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0, 0) &&
(long long)sp < (long long)PHYS_TO_XKPHYS(8, 0))
usp = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
XKPHYS_TO_PHYS((long long)sp));
#endif
else {
BUG();
usp = sp;
}
if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2)
ufunc = CKSEG1ADDR(lfunc);
#ifdef CONFIG_64BIT
else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0, 0) &&
(long long)lfunc < (long long)PHYS_TO_XKPHYS(8, 0))
ufunc = PHYS_TO_XKPHYS(K_CALG_UNCACHED,
XKPHYS_TO_PHYS((long long)lfunc));
#endif
else {
BUG();
ufunc = lfunc;
}
__asm__ __volatile__ (
" move $16, $sp\n"
" move $sp, %1\n"
" jalr %2\n"
" move $sp, $16"
: "=r" (ret)
: "r" (usp), "r" (ufunc)
: "$16", "$31");
return ret;
}