On Thu, 23 Jun 2005, Andy Isaacson wrote: > > Is it really the case? Perhaps it doesn't know the symbolic name of the > > register which has only been added recently. Replacing it with $31 should > > fix the problem, but your patch is obviously correct regardless. > > Yeah, you're right, my old gas just doesn't know $ra. s/ra/31/g works > as well. Here's my proposal to fix run_uncached() -- it works correctly for me for both 32-bit and 64-bit builds (current code crashes for me for 64 bits, because as a result of the bad calculation a jump outside any valid address space is attempted). I've inspected generated machine code to make sure it's correct as well. Unfortunately with this code GCC spits out a few bogus warnings for 32-bit builds (this is supposed to be a "non-bug" of the compiler -- see "http://gcc.gnu.org/bugzilla/show_bug.cgi?id=12963"; for details). I'm not sure struggling hard to get rid of these warnings, possibly complicating code, is worth the hassle; GCC should be fixed instead. Unless there are objections I'd like to apply this patch. Maciej patch-mips-2.6.12-20050620-run_uncached-8 diff -up --recursive --new-file linux-mips-2.6.12-20050620.macro/arch/mips/lib/uncached.c linux-mips-2.6.12-20050620/arch/mips/lib/uncached.c --- linux-mips-2.6.12-20050620.macro/arch/mips/lib/uncached.c 2005-04-25 16:36:23.000000000 +0000 +++ linux-mips-2.6.12-20050620/arch/mips/lib/uncached.c 2005-06-23 18:24:58.000000000 +0000 @@ -4,31 +4,71 @@ * for more details. * * Copyright (C) 2005 Thiemo Seufer + * Copyright (C) 2005 MIPS Technologies, Inc. All rights reserved. + * Author: Maciej W. Rozycki <macro@xxxxxxxx> */ + #include <linux/init.h> #include <asm/addrspace.h> +#include <asm/bug.h> + +#ifndef CKSEG2 +#define CKSEG2 CKSSEG +#endif +#ifndef TO_PHYS_MASK +#define TO_PHYS_MASK -1 +#endif /* - * FUNC is executed in the uncached segment CKSEG1. This works only if - * both code and stack live in CKSEG0. The stack handling works because - * we don't handle stack arguments or more complex return values, so we - * can avoid to share the same stack area between cached and uncached - * mode. + * 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 __init run_uncached(void *func) { - register unsigned long sp __asm__("$sp"); - register unsigned long ret __asm__("$2"); - unsigned long usp = sp - CAC_BASE + UNCAC_BASE; - unsigned long ufunc = func - CAC_BASE + UNCAC_BASE; + register long sp __asm__("$sp"); + register long ret __asm__("$2"); + long lfunc = (long)func, ufunc; + long usp; + + if (sp >= (long)CKSEG0 && sp < (long)CKSEG2) + usp = CKSEG1ADDR(sp); + else if ((long long)sp >= (long long)PHYS_TO_XKPHYS(0LL, 0) && + (long long)sp < (long long)PHYS_TO_XKPHYS(8LL, 0)) + usp = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED, + XKPHYS_TO_PHYS((long long)sp)); + else { + BUG(); + usp = sp; + } + if (lfunc >= (long)CKSEG0 && lfunc < (long)CKSEG2) + ufunc = CKSEG1ADDR(lfunc); + else if ((long long)lfunc >= (long long)PHYS_TO_XKPHYS(0LL, 0) && + (long long)lfunc < (long long)PHYS_TO_XKPHYS(8LL, 0)) + ufunc = PHYS_TO_XKPHYS((long long)K_CALG_UNCACHED, + XKPHYS_TO_PHYS((long long)lfunc)); + else { + BUG(); + ufunc = lfunc; + } __asm__ __volatile__ ( - " move $16, $sp\n" - " move $sp, %1\n" - " jalr $ra, %2\n" - " move $sp, $16" - : "=&r" (ret) + " move $16, $sp\n" + " move $sp, %1\n" + " jalr %2\n" + " move $sp, $16" + : "=r" (ret) : "r" (usp), "r" (ufunc) : "$16", "$31");
