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authorPaul Burton <paul.burton@mips.com>2018-07-27 18:23:18 -0700
committerPaul Burton <paul.burton@mips.com>2018-07-30 10:27:20 -0700
commit0d0e14770d4487a7ede8df93d82305cbfac2d453 (patch)
tree561659734c25359b2790133f831790bfb4889290 /arch/mips/include/asm/page.h
parent28ec2238f37e72a3a40a7eb46893e7651bcc40a6 (diff)
MIPS: Make (UN)CAC_ADDR() PHYS_OFFSET-agnostic
Converting an address between cached & uncached (typically addresses in (c)kseg0 & (c)kseg1 or 2 xkphys regions) should not depend upon PHYS_OFFSET in any way - we're converting from a virtual address in one unmapped region to a virtual address in another unmapped region. For some reason our CAC_ADDR() & UNCAC_ADDR() macros make use of PAGE_OFFSET, which typically includes PHYS_OFFSET. This means that platforms with a non-zero PHYS_OFFSET typically have to workaround miscalculation by these 2 macros by also defining UNCAC_BASE to a value that isn't really correct. It appears that an attempt has previously been made to address this with commit 3f4579252aa1 ("MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET") which was later undone by commit ed3ce16c3d2b ("Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"") which also introduced the ar7 workaround. That attempt at a fix was roughly equivalent, but essentially caused the CAC_ADDR() & UNCAC_ADDR() macros to cancel out PHYS_OFFSET by adding & then subtracting it again. In his revert Leonid is correct that using PHYS_OFFSET makes no sense in the context of these macros, but appears to have missed its inclusion via PAGE_OFFSET which means PHYS_OFFSET actually had an effect after the revert rather than before it. Here we fix this by modifying CAC_ADDR() & UNCAC_ADDR() to stop using PAGE_OFFSET (& thus PHYS_OFFSET), instead using __pa() & __va() along with UNCAC_BASE. For UNCAC_ADDR(), __pa() will convert a cached address to a physical address which we can simply use as an offset from UNCAC_BASE to obtain an address in the uncached region. For CAC_ADDR() we can undo the effect of UNCAC_ADDR() by subtracting UNCAC_BASE and using __va() on the result. With this change made, remove definitions of UNCAC_BASE from the ar7 & pic32 platforms which appear to have defined them only to workaround this problem. Signed-off-by: Paul Burton <paul.burton@mips.com> References: 3f4579252aa1 ("MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET") References: ed3ce16c3d2b ("Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"") Patchwork: https://patchwork.linux-mips.org/patch/20046/ Cc: Florian Fainelli <f.fainelli@gmail.com> Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org Cc: Vladimir Kondratiev <vladimir.kondratiev@intel.com>
Diffstat (limited to 'arch/mips/include/asm/page.h')
-rw-r--r--arch/mips/include/asm/page.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index ad461216b5a1..a051b82f8009 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -252,8 +252,8 @@ extern int __virt_addr_valid(const volatile void *kaddr);
((current->personality & READ_IMPLIES_EXEC) ? VM_EXEC : 0) | \
VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC)
-#define UNCAC_ADDR(addr) ((addr) - PAGE_OFFSET + UNCAC_BASE)
-#define CAC_ADDR(addr) ((addr) - UNCAC_BASE + PAGE_OFFSET)
+#define UNCAC_ADDR(addr) (UNCAC_BASE + __pa(addr))
+#define CAC_ADDR(addr) ((unsigned long)__va((addr) - UNCAC_BASE))
#include <asm-generic/memory_model.h>
#include <asm-generic/getorder.h>