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arm64: Fix minor issues with the dcache_by_line_op macro

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The dcache_by_line_op macro suffers from a couple of small problems:

First, the GAS directives that are currently being used rely on
assembler behavior that is not documented, and probably not guaranteed
to produce the correct behavior going forward. As a result, we end up
with some undefined symbols in cache.o:

$ nm arch/arm64/mm/cache.o
         ...
         U civac
         ...
         U cvac
         U cvap
         U cvau

This is due to the fact that the comparisons used to select the
operation type in the dcache_by_line_op macro are comparing symbols
not strings, and even though it seems that GAS is doing the right
thing here (undefined symbols by the same name are equal to each
other), it seems unwise to rely on this.

Second, when patching in a DC CVAP instruction on CPUs that support it,
the fallback path consists of a DC CVAU instruction which may be
affected by CPU errata that require ARM64_WORKAROUND_CLEAN_CACHE.

Solve these issues by unrolling the various maintenance routines and
using the conditional directives that are documented as operating on
strings. To avoid the complexity of nested alternatives, we move the
DC CVAP patching to __clean_dcache_area_pop, falling back to a branch
to __clean_dcache_area_poc if DCPOP is not supported by the CPU.

Reported-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Suggested-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
Will Deacon 2018-12-10 13:39:48 +00:00
parent 2a9cee5b7a
commit 33309ecda0
2 changed files with 21 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
arch/arm64/include/asm/assembler.h
View File

@ -392,27 +392,33 @@ alternative_endif
* size: size of the region
* Corrupts: kaddr, size, tmp1, tmp2
*/
.macro __dcache_op_workaround_clean_cache, op, kaddr
alternative_if_not ARM64_WORKAROUND_CLEAN_CACHE
dc \op, \kaddr
alternative_else
dc civac, \kaddr
alternative_endif
.endm
.macro dcache_by_line_op op, domain, kaddr, size, tmp1, tmp2
dcache_line_size \tmp1, \tmp2
add \size, \kaddr, \size
sub \tmp2, \tmp1, #1
bic \kaddr, \kaddr, \tmp2
9998:
.if (\op == cvau || \op == cvac)
alternative_if_not ARM64_WORKAROUND_CLEAN_CACHE
dc \op, \kaddr
alternative_else
dc civac, \kaddr
alternative_endif
.elseif (\op == cvap)
alternative_if ARM64_HAS_DCPOP
sys 3, c7, c12, 1, \kaddr // dc cvap
alternative_else
dc cvac, \kaddr
alternative_endif
.ifc \op, cvau
__dcache_op_workaround_clean_cache \op, \kaddr
.else
.ifc \op, cvac
__dcache_op_workaround_clean_cache \op, \kaddr
.else
.ifc \op, cvap
sys 3, c7, c12, 1, \kaddr // dc cvap
.else
dc \op, \kaddr
.endif
.endif
.endif
add \kaddr, \kaddr, \tmp1
cmp \kaddr, \size
b.lo 9998b

3
arch/arm64/mm/cache.S
View File

@ -212,6 +212,9 @@ ENDPROC(__dma_clean_area)
* - size - size in question
*/
ENTRY(__clean_dcache_area_pop)
alternative_if_not ARM64_HAS_DCPOP
b __clean_dcache_area_poc
alternative_else_nop_endif
dcache_by_line_op cvap, sy, x0, x1, x2, x3
ret
ENDPIPROC(__clean_dcache_area_pop)