[PATCH] arm64: ignore memory outside of the linear range
From: catalin.marinas@arm.com (Catalin Marinas)
Date: 2015-08-17 10:40:50
On Sat, Aug 15, 2015 at 02:13:44PM +0200, Ard Biesheuvel wrote:
We need to ensure that we don't try to map system RAM ranges whose offset relative to the start of the kernel image exceeds the size of the linear range. This may happen even on systems that don't have huge amounts of RAM if it is laid out very sparsely. Signed-off-by: Ard Biesheuvel <redacted> --- This is the minimal fix for addressing the issue we discussed. I dropped the other changes for now, let's revisit those when (if) my patches for decoupling the kernel mapping from the linear mapping are back under discussion. I will leave it up to the maintainers whether this constitutes a bugfix or not, but since this has never worked from the beginning afaict, I don't think it belongs in stable per se.
Even though it is not a regression, I think it is a bug fix and it's worth cc'ing stable (though we could push it after 4.3-rc1).
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index ad87ce826cce..c65e57d4c3e7 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c@@ -158,6 +158,19 @@ early_param("mem", early_mem); void __init arm64_memblock_init(void) { + /* + * Remove the memory that we will not be able to cover + * with the linear mapping. + */ + const s64 linear_region_size = -(s64)PAGE_OFFSET; + + if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) { + pr_warn("Ignoring memory outside of linear range (0x%012llx - 0x%012llx)\n", + memstart_addr + linear_region_size, + (u64)memblock_end_of_DRAM() - 1); + memblock_remove(memstart_addr + linear_region_size, ULLONG_MAX); + }
For memory blocks below PHYS_OFFSET, we ignore them in early_init_dt_add_memory_arch() directly (and also print a warning). Could we not do something similar for higher blocks? This function has a check for MAX_PHYS_ADDR but thats -1ULL, so I guess the check is pretty much useless. We should allow the arch code define this macro and only leave the current value as default if not overridden. -- Catalin