Commit 2dece445 authored by Laura Abbott's avatar Laura Abbott Committed by Will Deacon

mm/cma: Cleanup highmem check

6b101e2a ("mm/CMA: fix boot regression due to physical address of
high_memory") added checks to use __pa_nodebug on x86 since
CONFIG_DEBUG_VIRTUAL complains about high_memory not being linearlly
mapped. arm64 is now getting support for CONFIG_DEBUG_VIRTUAL as well.
Rather than add an explosion of arches to the #ifdef, switch to an
alternate method to calculate the physical start of highmem using
the page before highmem starts. This avoids the need for the #ifdef and
extra __pa_nodebug calls.
Reviewed-by: default avatarMark Rutland <>
Tested-by: default avatarMark Rutland <>
Signed-off-by: default avatarLaura Abbott <>
Signed-off-by: default avatarWill Deacon <>
parent fa5b6ec9
......@@ -235,18 +235,13 @@ int __init cma_declare_contiguous(phys_addr_t base,
phys_addr_t highmem_start;
int ret = 0;
#ifdef CONFIG_X86
* high_memory isn't direct mapped memory so retrieving its physical
* address isn't appropriate. But it would be useful to check the
* physical address of the highmem boundary so it's justifiable to get
* the physical address from it. On x86 there is a validation check for
* this case, so the following workaround is needed to avoid it.
* We can't use __pa(high_memory) directly, since high_memory
* isn't a valid direct map VA, and DEBUG_VIRTUAL will (validly)
* complain. Find the boundary by adding one to the last valid
* address.
highmem_start = __pa_nodebug(high_memory);
highmem_start = __pa(high_memory);
highmem_start = __pa(high_memory - 1) + 1;
pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
__func__, &size, &base, &limit, &alignment);
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