| Message ID | 20191224064126.183670-1-ruscur@russell.cc (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/2] powerpc/book3s64/hash: Disable 16M linear mapping size if not aligned | expand |
On Tue, 2019-12-24 at 06:41:25 UTC, Russell Currey wrote: > With STRICT_KERNEL_RWX on in a relocatable kernel under the hash MMU, if > the position the kernel is loaded at is not 16M aligned, the kernel > miscalculates its ALIGN*()s and things go horribly wrong. > > We can easily avoid this when selecting the linear mapping size, so do > so and print a warning. I tested this for various alignments and as > long as the position is 64K aligned it's fine (the base requirement for > powerpc). > > Signed-off-by: Russell Currey <ruscur@russell.cc> Series applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/970d54f99ceac5bbf27929cb5ebfe18338ba1543 cheers
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c index b30435c7d804..523d4d39d11e 100644 --- a/arch/powerpc/mm/book3s64/hash_utils.c +++ b/arch/powerpc/mm/book3s64/hash_utils.c @@ -652,6 +652,7 @@ static void init_hpte_page_sizes(void) static void __init htab_init_page_sizes(void) { + bool aligned = true; init_hpte_page_sizes(); if (!debug_pagealloc_enabled()) { @@ -659,7 +660,15 @@ static void __init htab_init_page_sizes(void) * Pick a size for the linear mapping. Currently, we only * support 16M, 1M and 4K which is the default */ - if (mmu_psize_defs[MMU_PAGE_16M].shift) + if (IS_ENABLED(STRICT_KERNEL_RWX) && + (unsigned long)_stext % 0x1000000) { + if (mmu_psize_defs[MMU_PAGE_16M].shift) + pr_warn("Kernel not 16M aligned, " + "disabling 16M linear map alignment"); + aligned = false; + } + + if (mmu_psize_defs[MMU_PAGE_16M].shift && aligned) mmu_linear_psize = MMU_PAGE_16M; else if (mmu_psize_defs[MMU_PAGE_1M].shift) mmu_linear_psize = MMU_PAGE_1M;
With STRICT_KERNEL_RWX on in a relocatable kernel under the hash MMU, if the position the kernel is loaded at is not 16M aligned, the kernel miscalculates its ALIGN*()s and things go horribly wrong. We can easily avoid this when selecting the linear mapping size, so do so and print a warning. I tested this for various alignments and as long as the position is 64K aligned it's fine (the base requirement for powerpc). Signed-off-by: Russell Currey <ruscur@russell.cc> --- arch/powerpc/mm/book3s64/hash_utils.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)