arm64: Avoid aligning normal memory pointers in __memcpy_{to,from}io
__memcpy_{to,from}io fall back to byte-at-a-time copying if both the source and destination pointers are not 8-byte aligned. Since one of the pointers always points at normal memory, this is unnecessary and detrimental to performance, so only do byte copying until we hit an 8-byte boundary for the device pointer. This change was motivated by performance issues in the pstore driver. On a test platform, measuring probe time for pstore, console buffer size of 1/4MB and pmsg of 1/2MB, was in the 90-107ms region. Change managed to reduce it to 10-25ms, an improvement in boot time. Cc: Kees Cook <keescook@chromium.org> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Anton Vorontsov <anton@enomsg.org> Cc: Robin Murphy <robin.murphy@arm.com> Signed-off-by: Mark Salyzyn <salyzyn@android.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
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@ -25,8 +25,7 @@
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*/
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void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
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{
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while (count && (!IS_ALIGNED((unsigned long)from, 8) ||
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!IS_ALIGNED((unsigned long)to, 8))) {
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while (count && !IS_ALIGNED((unsigned long)from, 8)) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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@ -54,23 +53,22 @@ EXPORT_SYMBOL(__memcpy_fromio);
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*/
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void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
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{
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while (count && (!IS_ALIGNED((unsigned long)to, 8) ||
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!IS_ALIGNED((unsigned long)from, 8))) {
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__raw_writeb(*(volatile u8 *)from, to);
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while (count && !IS_ALIGNED((unsigned long)to, 8)) {
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__raw_writeb(*(u8 *)from, to);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(*(volatile u64 *)from, to);
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__raw_writeq(*(u64 *)from, to);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(*(volatile u8 *)from, to);
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__raw_writeb(*(u8 *)from, to);
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from++;
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to++;
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count--;
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