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h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kN/DSLa9xzEUdkwYNukltvI0/VyWifB4opqaJ+D8yB0dGBzrnT+2zl4H/tlk1LAm7 M/evJFeCzkTtrWoIBSkAm2pMxrCge3Jgl3FjMX1o/jFHC0mlUoAH8ghYdWNSK4qzOh 5VmQw4t2+PyQFniEBiF/sEGCG/+48/sl7JN6cqWLXJubKx6MnBW2rxRKr6kCtD0XuR HX5d88uUv6tvaQPn7W1o0bmHs0DCdRJVB1Z4sjn6vH7hmIhABfepHdbpuccyPQUt0Y aQT/tXHGs+SLYg9NG2F8XXgn+Mz8Ti0iZ+vCdYndV7HMcORtOdC0vTppOGe6UIJ6SY Gxq9uO/e6QmaQ== Date: Mon, 28 Oct 2024 17:03:55 +0200 From: Mike Rapoport To: John Hubbard Cc: Andrew Morton , Thomas Gleixner , David Hildenbrand , Will Deacon , Alistair Popple , Jordan Niethe , linux-arm-kernel@lists.infradead.org, x86@kernel.org, linux-mm@kvack.org, LKML Subject: Re: [PATCH] kaslr: rename physmem_end and PHYSMEM_END to direct_map_physmem_end Message-ID: References: <20241009025024.89813-1-jhubbard@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241009025024.89813-1-jhubbard@nvidia.com> X-Stat-Signature: 699pj5a4kok1p6778cce6akehhjpchqq X-Rspamd-Queue-Id: C8AB12002E X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1730128058-764555 X-HE-Meta: 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 /76cNmSm rdi+moXUdNDKkkYVb247qxgagwLVk7YlW/fIGQgTnfBF7I3KMMpBHnRZ13QjSDT3cZX35gvfTjRodvKfvd34esKaxkAsAdS/y+MdTrGxDhNPN1rmUHMqoJsNFzfnafD5dF3HoWbGgR0fAjGkb/B1ds45PCwRBqfhiT1lsnZlpbYmFRchuDDQHRy2ebUd0u3mR6vpi3Pbo2SvTQqGp67DbiEVFv/wioTYagweFW8LYwQfA4YDntvn08vHiN3i9c7JN0WryEiMbV+wc0k3rJDrn9Z2mvSuzcOdKctlkviR/b+tlSatgQp+4Ddf0i0PDSb1Tbv9xqTaUxbLUM+Z0VoeC4tBBrUV8dMvFK7zSK/gkD2rAOYetLlXGXGwv3x+pnpouJK0lmt3n8Z/oiyqGoINnKjrY7CF4UlIvtks1H9P5/5efyMHe0iFJWg4ytQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Oct 08, 2024 at 07:50:24PM -0700, John Hubbard wrote: > For clarity. It's increasingly hard to reason about the code, when KASLR > is moving around the boundaries. In this case where KASLR is randomizing > the location of the kernel image within physical memory, the maximum > number of address bits for physical memory has not changed. > > What has changed is the ending address of memory that is allowed to be > directly mapped by the kernel. > > Let's name the variable, and the associated macro accordingly. > > Also, enhance the comment above the direct_map_physmem_end definition, > to further clarify how this all works. > > Cc: Thomas Gleixner > Cc: Alistair Popple > Cc: Jordan Niethe > Cc: David Hildenbrand > Signed-off-by: John Hubbard Reviewed-by: Mike Rapoport (Microsoft) > --- > > David Hildenbrand, I recall you had an unanswered question in this > vicinity [1] when tglx's recent kaslr fix was being reviewed. Maybe this > will help with that. To David's question, physmem_end (and now direct_map_physmem_end) is updated kernel_randomize_memory() via kaslr_regions[0].base > > [1] https://lore.kernel.org/linux-mm/ee205448-5fdd-495e-9d7c-c8a2b59f9c9e@roeck-us.net/T/#mdf442f077c9023590e144dbed2b04a109793484d > > thanks, > John Hubbard > > > arch/arm64/include/asm/memory.h | 2 +- > arch/x86/include/asm/page_64.h | 2 +- > arch/x86/include/asm/pgtable_64_types.h | 2 +- > arch/x86/mm/init_64.c | 2 +- > arch/x86/mm/kaslr.c | 14 +++++++++----- > include/linux/mm.h | 6 +++--- > kernel/resource.c | 4 ++-- > mm/memory_hotplug.c | 2 +- > mm/sparse.c | 2 +- > 9 files changed, 20 insertions(+), 16 deletions(-) > > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index 0480c61dbb4f..73eaa8c2536a 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -110,7 +110,7 @@ > #define PAGE_END (_PAGE_END(VA_BITS_MIN)) > #endif /* CONFIG_KASAN */ > > -#define PHYSMEM_END __pa(PAGE_END - 1) > +#define DIRECT_MAP_PHYSMEM_END __pa(PAGE_END - 1) > > #define MIN_THREAD_SHIFT (14 + KASAN_THREAD_SHIFT) > > diff --git a/arch/x86/include/asm/page_64.h b/arch/x86/include/asm/page_64.h > index f3d257c45225..d63576608ce7 100644 > --- a/arch/x86/include/asm/page_64.h > +++ b/arch/x86/include/asm/page_64.h > @@ -17,7 +17,7 @@ extern unsigned long phys_base; > extern unsigned long page_offset_base; > extern unsigned long vmalloc_base; > extern unsigned long vmemmap_base; > -extern unsigned long physmem_end; > +extern unsigned long direct_map_physmem_end; > > static __always_inline unsigned long __phys_addr_nodebug(unsigned long x) > { > diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h > index a98e53491a4e..ec68f8369bdc 100644 > --- a/arch/x86/include/asm/pgtable_64_types.h > +++ b/arch/x86/include/asm/pgtable_64_types.h > @@ -141,7 +141,7 @@ extern unsigned int ptrs_per_p4d; > #endif /* CONFIG_DYNAMIC_MEMORY_LAYOUT */ > > #ifdef CONFIG_RANDOMIZE_MEMORY > -# define PHYSMEM_END physmem_end > +# define DIRECT_MAP_PHYSMEM_END direct_map_physmem_end > #endif > > /* > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index ff253648706f..5a564130b9d0 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -961,7 +961,7 @@ int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages, > unsigned long end = ((start_pfn + nr_pages) << PAGE_SHIFT) - 1; > int ret; > > - if (WARN_ON_ONCE(end > PHYSMEM_END)) > + if (WARN_ON_ONCE(end > DIRECT_MAP_PHYSMEM_END)) > return -ERANGE; > > ret = __add_pages(nid, start_pfn, nr_pages, params); > diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c > index 230f1dee4f09..70d3353c92fa 100644 > --- a/arch/x86/mm/kaslr.c > +++ b/arch/x86/mm/kaslr.c > @@ -52,7 +52,7 @@ static __initdata struct kaslr_memory_region { > } kaslr_regions[] = { > { > .base = &page_offset_base, > - .end = &physmem_end, > + .end = &direct_map_physmem_end, > }, > { > .base = &vmalloc_base, > @@ -62,8 +62,12 @@ static __initdata struct kaslr_memory_region { > }, > }; > > -/* The end of the possible address space for physical memory */ > -unsigned long physmem_end __ro_after_init; > +/* > + * The end of the physical address space that can be mapped directly by the > + * kernel. This starts out at (1< + * that in order to increase the available entropy for mapping other regions. > + */ > +unsigned long direct_map_physmem_end __ro_after_init; > > /* Get size in bytes used by the memory region */ > static inline unsigned long get_padding(struct kaslr_memory_region *region) > @@ -94,7 +98,7 @@ void __init kernel_randomize_memory(void) > BUILD_BUG_ON(vaddr_end > __START_KERNEL_map); > > /* Preset the end of the possible address space for physical memory */ > - physmem_end = ((1ULL << MAX_PHYSMEM_BITS) - 1); > + direct_map_physmem_end = ((1ULL << MAX_PHYSMEM_BITS) - 1); > if (!kaslr_memory_enabled()) > return; > > @@ -145,7 +149,7 @@ void __init kernel_randomize_memory(void) > vaddr += get_padding(&kaslr_regions[i]); > /* > * KASLR trims the maximum possible size of the > - * direct-map. Update the physmem_end boundary. > + * direct-map. Update the direct_map_physmem_end boundary. > * No rounding required as the region starts > * PUD aligned and size is in units of TB. > */ > diff --git a/include/linux/mm.h b/include/linux/mm.h > index ecf63d2b0582..92c35fb60d18 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -97,11 +97,11 @@ extern const int mmap_rnd_compat_bits_max; > extern int mmap_rnd_compat_bits __read_mostly; > #endif > > -#ifndef PHYSMEM_END > +#ifndef DIRECT_MAP_PHYSMEM_END > # ifdef MAX_PHYSMEM_BITS > -# define PHYSMEM_END ((1ULL << MAX_PHYSMEM_BITS) - 1) > +# define DIRECT_MAP_PHYSMEM_END ((1ULL << MAX_PHYSMEM_BITS) - 1) > # else > -# define PHYSMEM_END (((phys_addr_t)-1)&~(1ULL<<63)) > +# define DIRECT_MAP_PHYSMEM_END (((phys_addr_t)-1)&~(1ULL<<63)) > # endif > #endif > > diff --git a/kernel/resource.c b/kernel/resource.c > index b730bd28b422..afa3ad09b834 100644 > --- a/kernel/resource.c > +++ b/kernel/resource.c > @@ -1871,7 +1871,7 @@ static resource_size_t gfr_start(struct resource *base, resource_size_t size, > if (flags & GFR_DESCENDING) { > resource_size_t end; > > - end = min_t(resource_size_t, base->end, PHYSMEM_END); > + end = min_t(resource_size_t, base->end, DIRECT_MAP_PHYSMEM_END); > return end - size + 1; > } > > @@ -1888,7 +1888,7 @@ static bool gfr_continue(struct resource *base, resource_size_t addr, > * @size did not wrap 0. > */ > return addr > addr - size && > - addr <= min_t(resource_size_t, base->end, PHYSMEM_END); > + addr <= min_t(resource_size_t, base->end, DIRECT_MAP_PHYSMEM_END); > } > > static resource_size_t gfr_next(resource_size_t addr, resource_size_t size, > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 621ae1015106..c43b4e7fb298 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1681,7 +1681,7 @@ struct range __weak arch_get_mappable_range(void) > > struct range mhp_get_pluggable_range(bool need_mapping) > { > - const u64 max_phys = PHYSMEM_END; > + const u64 max_phys = DIRECT_MAP_PHYSMEM_END; > struct range mhp_range; > > if (need_mapping) { > diff --git a/mm/sparse.c b/mm/sparse.c > index dc38539f8560..4cb9793f0b52 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -129,7 +129,7 @@ static inline int sparse_early_nid(struct mem_section *section) > static void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn, > unsigned long *end_pfn) > { > - unsigned long max_sparsemem_pfn = (PHYSMEM_END + 1) >> PAGE_SHIFT; > + unsigned long max_sparsemem_pfn = (DIRECT_MAP_PHYSMEM_END + 1) >> PAGE_SHIFT; > > /* > * Sanity checks - do not allow an architecture to pass > -- > 2.47.0 > > -- Sincerely yours, Mike.