Le 24/04/2024 à 13:09, Hari Bathini a écrit : > When KFENCE is enabled, total system memory is mapped at page level > granularity. But in radix MMU mode, ~3GB additional memory is needed > to map 100GB of system memory at page level granularity when compared > to using 2MB direct mapping. This is not desired considering KFENCE is > designed to be enabled in production kernels [1]. Also, mapping memory > allocated for KFENCE pool at page granularity seems sufficient enough > to enable KFENCE support. So, allocate __kfence_pool during bootup and > map it at page granularity instead of mapping all system memory at > page granularity.
That seems to be more or less copied from ARM64 ? Is that the best approach ? Can't you implement arch_kfence_init_pool() instead ? Also, it seems your patch only addresses PPC64. The same should be done for PPC32 and there are probably parts that should be common. > > Without patch: > # cat /proc/meminfo > MemTotal: 101201920 kB > > With patch: > # cat /proc/meminfo > MemTotal: 104483904 kB > > All kfence_test.c testcases passed with this patch. > > [1] https://lore.kernel.org/all/20201103175841.3495947-2-el...@google.com/ > > Signed-off-by: Hari Bathini <hbath...@linux.ibm.com> > --- > arch/powerpc/include/asm/kfence.h | 5 ++++ > arch/powerpc/mm/book3s64/radix_pgtable.c | 34 ++++++++++++++++++------ > arch/powerpc/mm/init_64.c | 14 ++++++++++ > 3 files changed, 45 insertions(+), 8 deletions(-) > > diff --git a/arch/powerpc/include/asm/kfence.h > b/arch/powerpc/include/asm/kfence.h > index 424ceef82ae6..18ec2b06ba1e 100644 > --- a/arch/powerpc/include/asm/kfence.h > +++ b/arch/powerpc/include/asm/kfence.h > @@ -8,6 +8,7 @@ > #ifndef __ASM_POWERPC_KFENCE_H > #define __ASM_POWERPC_KFENCE_H > > +#include <linux/kfence.h> Why do you need that ? It can't be needed by the extern bool you are adding below. If it is needed by some C file that includes asm/kfence.h, it should include linux/kfence.h by itself, see for instance mm/kfence/kfence_test.c and mm/kfence/core.c > #include <linux/mm.h> > #include <asm/pgtable.h> > > @@ -15,6 +16,10 @@ > #define ARCH_FUNC_PREFIX "." > #endif > > +#ifdef CONFIG_KFENCE > +extern bool kfence_early_init; > +#endif > + > static inline bool arch_kfence_init_pool(void) > { > return true; > diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c > b/arch/powerpc/mm/book3s64/radix_pgtable.c > index 15e88f1439ec..fccbf92f279b 100644 > --- a/arch/powerpc/mm/book3s64/radix_pgtable.c > +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c > @@ -31,6 +31,7 @@ > #include <asm/uaccess.h> > #include <asm/ultravisor.h> > #include <asm/set_memory.h> > +#include <asm/kfence.h> > > #include <trace/events/thp.h> > > @@ -291,9 +292,8 @@ static unsigned long next_boundary(unsigned long addr, > unsigned long end) > return end; > } > > -static int __meminit create_physical_mapping(unsigned long start, > - unsigned long end, > - int nid, pgprot_t _prot) > +static int __meminit create_physical_mapping(unsigned long start, unsigned > long end, int nid, > + pgprot_t _prot, unsigned long > mapping_sz_limit) > { > unsigned long vaddr, addr, mapping_size = 0; > bool prev_exec, exec = false; > @@ -301,7 +301,10 @@ static int __meminit create_physical_mapping(unsigned > long start, > int psize; > unsigned long max_mapping_size = memory_block_size; > > - if (debug_pagealloc_enabled_or_kfence()) > + if (mapping_sz_limit < max_mapping_size) > + max_mapping_size = mapping_sz_limit; > + > + if (debug_pagealloc_enabled()) > max_mapping_size = PAGE_SIZE; > > start = ALIGN(start, PAGE_SIZE); > @@ -358,6 +361,7 @@ static int __meminit create_physical_mapping(unsigned > long start, > > static void __init radix_init_pgtable(void) > { > + phys_addr_t kfence_pool __maybe_unused; Don't do that. Avoid using __maybe_unused. Instead, declare this var where it is used. > unsigned long rts_field; > phys_addr_t start, end; > u64 i; > @@ -365,6 +369,13 @@ static void __init radix_init_pgtable(void) > /* We don't support slb for radix */ > slb_set_size(0); > > +#ifdef CONFIG_KFENCE > + if (kfence_early_init) { Declare kfence_pool here. > + kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE); > + memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE); > + } > +#endif > + > /* > * Create the linear mapping > */ > @@ -380,10 +391,18 @@ static void __init radix_init_pgtable(void) > continue; > } > > - WARN_ON(create_physical_mapping(start, end, > - -1, PAGE_KERNEL)); > + WARN_ON(create_physical_mapping(start, end, -1, PAGE_KERNEL, > ~0UL)); > } > > +#ifdef CONFIG_KFENCE > + if (kfence_early_init) { > + create_physical_mapping(kfence_pool, kfence_pool + > KFENCE_POOL_SIZE, -1, > + PAGE_KERNEL, PAGE_SIZE); > + memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE); > + __kfence_pool = __va(kfence_pool); > + } > +#endif > + > if (!cpu_has_feature(CPU_FTR_HVMODE) && > cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) { > /* > @@ -874,8 +893,7 @@ int __meminit radix__create_section_mapping(unsigned long > start, > return -1; > } > > - return create_physical_mapping(__pa(start), __pa(end), > - nid, prot); > + return create_physical_mapping(__pa(start), __pa(end), nid, prot, ~0UL); > } > > int __meminit radix__remove_section_mapping(unsigned long start, unsigned > long end) > diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c > index d96bbc001e73..8155bfd6c16b 100644 > --- a/arch/powerpc/mm/init_64.c > +++ b/arch/powerpc/mm/init_64.c > @@ -64,6 +64,20 @@ > > #include <mm/mmu_decl.h> > > +#ifdef CONFIG_KFENCE > +bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL; > + > +static int __init parse_kfence_early_init(char *arg) > +{ > + int val; > + > + if (get_option(&arg, &val)) > + kfence_early_init = !!val; > + return 0; > +} > +early_param("kfence.sample_interval", parse_kfence_early_init); > +#endif > + > #ifdef CONFIG_SPARSEMEM_VMEMMAP > /* > * Given an address within the vmemmap, determine the page that
