580 lines
14 KiB
C
580 lines
14 KiB
C
/*
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* Handle caching attributes in page tables (PAT)
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*
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* Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
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* Suresh B Siddha <suresh.b.siddha@intel.com>
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*
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* Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen.
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*/
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#include <linux/mm.h>
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#include <linux/kernel.h>
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#include <linux/gfp.h>
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#include <linux/fs.h>
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#include <linux/bootmem.h>
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#include <asm/msr.h>
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#include <asm/tlbflush.h>
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#include <asm/processor.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include <asm/pat.h>
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#include <asm/e820.h>
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#include <asm/cacheflush.h>
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#include <asm/fcntl.h>
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#include <asm/mtrr.h>
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#include <asm/io.h>
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#ifdef CONFIG_X86_PAT
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int __read_mostly pat_enabled = 1;
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void __cpuinit pat_disable(char *reason)
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{
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pat_enabled = 0;
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printk(KERN_INFO "%s\n", reason);
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}
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static int __init nopat(char *str)
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{
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pat_disable("PAT support disabled.");
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return 0;
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}
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early_param("nopat", nopat);
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#endif
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static int debug_enable;
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static int __init pat_debug_setup(char *str)
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{
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debug_enable = 1;
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return 0;
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}
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__setup("debugpat", pat_debug_setup);
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#define dprintk(fmt, arg...) \
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do { if (debug_enable) printk(KERN_INFO fmt, ##arg); } while (0)
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static u64 __read_mostly boot_pat_state;
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enum {
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PAT_UC = 0, /* uncached */
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PAT_WC = 1, /* Write combining */
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PAT_WT = 4, /* Write Through */
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PAT_WP = 5, /* Write Protected */
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PAT_WB = 6, /* Write Back (default) */
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PAT_UC_MINUS = 7, /* UC, but can be overriden by MTRR */
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};
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#define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))
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void pat_init(void)
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{
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u64 pat;
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if (!pat_enabled)
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return;
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/* Paranoia check. */
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if (!cpu_has_pat && boot_pat_state) {
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/*
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* If this happens we are on a secondary CPU, but
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* switched to PAT on the boot CPU. We have no way to
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* undo PAT.
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*/
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printk(KERN_ERR "PAT enabled, "
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"but not supported by secondary CPU\n");
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BUG();
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}
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/* Set PWT to Write-Combining. All other bits stay the same */
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/*
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* PTE encoding used in Linux:
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* PAT
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* |PCD
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* ||PWT
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* |||
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* 000 WB _PAGE_CACHE_WB
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* 001 WC _PAGE_CACHE_WC
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* 010 UC- _PAGE_CACHE_UC_MINUS
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* 011 UC _PAGE_CACHE_UC
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* PAT bit unused
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*/
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pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |
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PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
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/* Boot CPU check */
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if (!boot_pat_state)
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rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
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wrmsrl(MSR_IA32_CR_PAT, pat);
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printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n",
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smp_processor_id(), boot_pat_state, pat);
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}
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#undef PAT
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static char *cattr_name(unsigned long flags)
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{
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switch (flags & _PAGE_CACHE_MASK) {
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case _PAGE_CACHE_UC: return "uncached";
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case _PAGE_CACHE_UC_MINUS: return "uncached-minus";
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case _PAGE_CACHE_WB: return "write-back";
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case _PAGE_CACHE_WC: return "write-combining";
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default: return "broken";
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}
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}
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/*
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* The global memtype list keeps track of memory type for specific
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* physical memory areas. Conflicting memory types in different
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* mappings can cause CPU cache corruption. To avoid this we keep track.
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*
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* The list is sorted based on starting address and can contain multiple
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* entries for each address (this allows reference counting for overlapping
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* areas). All the aliases have the same cache attributes of course.
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* Zero attributes are represented as holes.
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*
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* Currently the data structure is a list because the number of mappings
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* are expected to be relatively small. If this should be a problem
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* it could be changed to a rbtree or similar.
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*
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* memtype_lock protects the whole list.
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*/
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struct memtype {
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u64 start;
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u64 end;
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unsigned long type;
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struct list_head nd;
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};
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static LIST_HEAD(memtype_list);
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static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */
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/*
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* Does intersection of PAT memory type and MTRR memory type and returns
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* the resulting memory type as PAT understands it.
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* (Type in pat and mtrr will not have same value)
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* The intersection is based on "Effective Memory Type" tables in IA-32
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* SDM vol 3a
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*/
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static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)
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{
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u8 mtrr_type;
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/*
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* We return the PAT request directly for types where PAT takes
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* precedence with respect to MTRR and for UC_MINUS.
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* Consistency checks with other PAT requests is done later
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* while going through memtype list.
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*/
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if (req_type == _PAGE_CACHE_WC ||
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req_type == _PAGE_CACHE_UC_MINUS ||
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req_type == _PAGE_CACHE_UC)
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return req_type;
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/*
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* Look for MTRR hint to get the effective type in case where PAT
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* request is for WB.
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*/
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mtrr_type = mtrr_type_lookup(start, end);
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if (mtrr_type == MTRR_TYPE_UNCACHABLE)
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return _PAGE_CACHE_UC;
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if (mtrr_type == MTRR_TYPE_WRCOMB)
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return _PAGE_CACHE_WC;
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return _PAGE_CACHE_WB;
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}
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/*
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* req_type typically has one of the:
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* - _PAGE_CACHE_WB
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* - _PAGE_CACHE_WC
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* - _PAGE_CACHE_UC_MINUS
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* - _PAGE_CACHE_UC
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*
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* req_type will have a special case value '-1', when requester want to inherit
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* the memory type from mtrr (if WB), existing PAT, defaulting to UC_MINUS.
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*
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* If ret_type is NULL, function will return an error if it cannot reserve the
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* region with req_type. If ret_type is non-null, function will return
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* available type in ret_type in case of no error. In case of any error
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* it will return a negative return value.
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*/
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int reserve_memtype(u64 start, u64 end, unsigned long req_type,
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unsigned long *ret_type)
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{
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struct memtype *new_entry = NULL;
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struct memtype *parse;
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unsigned long actual_type;
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int err = 0;
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/* Only track when pat_enabled */
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if (!pat_enabled) {
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/* This is identical to page table setting without PAT */
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if (ret_type) {
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if (req_type == -1) {
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*ret_type = _PAGE_CACHE_WB;
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} else {
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*ret_type = req_type & _PAGE_CACHE_MASK;
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}
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}
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return 0;
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}
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/* Low ISA region is always mapped WB in page table. No need to track */
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if (start >= ISA_START_ADDRESS && (end - 1) <= ISA_END_ADDRESS) {
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if (ret_type)
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*ret_type = _PAGE_CACHE_WB;
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return 0;
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}
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if (req_type == -1) {
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/*
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* Call mtrr_lookup to get the type hint. This is an
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* optimization for /dev/mem mmap'ers into WB memory (BIOS
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* tools and ACPI tools). Use WB request for WB memory and use
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* UC_MINUS otherwise.
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*/
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u8 mtrr_type = mtrr_type_lookup(start, end);
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if (mtrr_type == MTRR_TYPE_WRBACK) {
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req_type = _PAGE_CACHE_WB;
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actual_type = _PAGE_CACHE_WB;
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} else {
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req_type = _PAGE_CACHE_UC_MINUS;
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actual_type = _PAGE_CACHE_UC_MINUS;
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}
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} else {
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req_type &= _PAGE_CACHE_MASK;
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actual_type = pat_x_mtrr_type(start, end, req_type);
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}
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new_entry = kmalloc(sizeof(struct memtype), GFP_KERNEL);
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if (!new_entry)
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return -ENOMEM;
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new_entry->start = start;
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new_entry->end = end;
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new_entry->type = actual_type;
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if (ret_type)
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*ret_type = actual_type;
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spin_lock(&memtype_lock);
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/* Search for existing mapping that overlaps the current range */
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list_for_each_entry(parse, &memtype_list, nd) {
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struct memtype *saved_ptr;
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if (parse->start >= end) {
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dprintk("New Entry\n");
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list_add(&new_entry->nd, parse->nd.prev);
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new_entry = NULL;
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break;
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}
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if (start <= parse->start && end >= parse->start) {
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if (actual_type != parse->type && ret_type) {
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actual_type = parse->type;
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*ret_type = actual_type;
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new_entry->type = actual_type;
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}
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if (actual_type != parse->type) {
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printk(
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KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
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current->comm, current->pid,
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start, end,
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cattr_name(actual_type),
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cattr_name(parse->type));
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err = -EBUSY;
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break;
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}
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saved_ptr = parse;
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/*
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* Check to see whether the request overlaps more
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* than one entry in the list
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*/
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list_for_each_entry_continue(parse, &memtype_list, nd) {
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if (end <= parse->start) {
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break;
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}
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if (actual_type != parse->type) {
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printk(
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KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
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current->comm, current->pid,
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start, end,
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cattr_name(actual_type),
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cattr_name(parse->type));
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err = -EBUSY;
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break;
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}
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}
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if (err) {
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break;
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}
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dprintk("Overlap at 0x%Lx-0x%Lx\n",
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saved_ptr->start, saved_ptr->end);
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/* No conflict. Go ahead and add this new entry */
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list_add(&new_entry->nd, saved_ptr->nd.prev);
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new_entry = NULL;
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break;
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}
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if (start < parse->end) {
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if (actual_type != parse->type && ret_type) {
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actual_type = parse->type;
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*ret_type = actual_type;
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new_entry->type = actual_type;
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}
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if (actual_type != parse->type) {
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printk(
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KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
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current->comm, current->pid,
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start, end,
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cattr_name(actual_type),
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cattr_name(parse->type));
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err = -EBUSY;
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break;
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}
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saved_ptr = parse;
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/*
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* Check to see whether the request overlaps more
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* than one entry in the list
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*/
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list_for_each_entry_continue(parse, &memtype_list, nd) {
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if (end <= parse->start) {
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break;
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}
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if (actual_type != parse->type) {
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printk(
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KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
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current->comm, current->pid,
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start, end,
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cattr_name(actual_type),
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cattr_name(parse->type));
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err = -EBUSY;
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break;
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}
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}
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if (err) {
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break;
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}
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dprintk("Overlap at 0x%Lx-0x%Lx\n",
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saved_ptr->start, saved_ptr->end);
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/* No conflict. Go ahead and add this new entry */
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list_add(&new_entry->nd, &saved_ptr->nd);
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new_entry = NULL;
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break;
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}
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}
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if (err) {
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printk(KERN_INFO
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"reserve_memtype failed 0x%Lx-0x%Lx, track %s, req %s\n",
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start, end, cattr_name(new_entry->type),
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cattr_name(req_type));
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kfree(new_entry);
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spin_unlock(&memtype_lock);
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return err;
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}
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if (new_entry) {
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/* No conflict. Not yet added to the list. Add to the tail */
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list_add_tail(&new_entry->nd, &memtype_list);
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dprintk("New Entry\n");
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}
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if (ret_type) {
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dprintk(
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"reserve_memtype added 0x%Lx-0x%Lx, track %s, req %s, ret %s\n",
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start, end, cattr_name(actual_type),
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cattr_name(req_type), cattr_name(*ret_type));
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} else {
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dprintk(
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"reserve_memtype added 0x%Lx-0x%Lx, track %s, req %s\n",
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start, end, cattr_name(actual_type),
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cattr_name(req_type));
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}
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spin_unlock(&memtype_lock);
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return err;
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}
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int free_memtype(u64 start, u64 end)
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{
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struct memtype *ml;
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int err = -EINVAL;
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/* Only track when pat_enabled */
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if (!pat_enabled) {
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return 0;
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}
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/* Low ISA region is always mapped WB. No need to track */
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if (start >= ISA_START_ADDRESS && end <= ISA_END_ADDRESS) {
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return 0;
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}
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spin_lock(&memtype_lock);
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list_for_each_entry(ml, &memtype_list, nd) {
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if (ml->start == start && ml->end == end) {
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list_del(&ml->nd);
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kfree(ml);
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err = 0;
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break;
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}
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}
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spin_unlock(&memtype_lock);
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if (err) {
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printk(KERN_INFO "%s:%d freeing invalid memtype %Lx-%Lx\n",
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current->comm, current->pid, start, end);
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}
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dprintk("free_memtype request 0x%Lx-0x%Lx\n", start, end);
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return err;
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}
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/*
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* /dev/mem mmap interface. The memtype used for mapping varies:
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* - Use UC for mappings with O_SYNC flag
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* - Without O_SYNC flag, if there is any conflict in reserve_memtype,
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* inherit the memtype from existing mapping.
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* - Else use UC_MINUS memtype (for backward compatibility with existing
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* X drivers.
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*/
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pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
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unsigned long size, pgprot_t vma_prot)
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{
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return vma_prot;
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}
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#ifdef CONFIG_NONPROMISC_DEVMEM
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/* This check is done in drivers/char/mem.c in case of NONPROMISC_DEVMEM*/
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static inline int range_is_allowed(unsigned long pfn, unsigned long size)
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{
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return 1;
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}
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#else
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static inline int range_is_allowed(unsigned long pfn, unsigned long size)
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{
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u64 from = ((u64)pfn) << PAGE_SHIFT;
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u64 to = from + size;
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u64 cursor = from;
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while (cursor < to) {
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if (!devmem_is_allowed(pfn)) {
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printk(KERN_INFO
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"Program %s tried to access /dev/mem between %Lx->%Lx.\n",
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current->comm, from, to);
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return 0;
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}
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cursor += PAGE_SIZE;
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pfn++;
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}
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return 1;
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}
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#endif /* CONFIG_NONPROMISC_DEVMEM */
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int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
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unsigned long size, pgprot_t *vma_prot)
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{
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u64 offset = ((u64) pfn) << PAGE_SHIFT;
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unsigned long flags = _PAGE_CACHE_UC_MINUS;
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int retval;
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if (!range_is_allowed(pfn, size))
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return 0;
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if (file->f_flags & O_SYNC) {
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flags = _PAGE_CACHE_UC;
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}
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#ifdef CONFIG_X86_32
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/*
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* On the PPro and successors, the MTRRs are used to set
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* memory types for physical addresses outside main memory,
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* so blindly setting UC or PWT on those pages is wrong.
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* For Pentiums and earlier, the surround logic should disable
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* caching for the high addresses through the KEN pin, but
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* we maintain the tradition of paranoia in this code.
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*/
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if (!pat_enabled &&
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!(boot_cpu_has(X86_FEATURE_MTRR) ||
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boot_cpu_has(X86_FEATURE_K6_MTRR) ||
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boot_cpu_has(X86_FEATURE_CYRIX_ARR) ||
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boot_cpu_has(X86_FEATURE_CENTAUR_MCR)) &&
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(pfn << PAGE_SHIFT) >= __pa(high_memory)) {
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flags = _PAGE_CACHE_UC;
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}
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#endif
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/*
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* With O_SYNC, we can only take UC mapping. Fail if we cannot.
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* Without O_SYNC, we want to get
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* - WB for WB-able memory and no other conflicting mappings
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* - UC_MINUS for non-WB-able memory with no other conflicting mappings
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* - Inherit from confliting mappings otherwise
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|
*/
|
|
if (flags != _PAGE_CACHE_UC_MINUS) {
|
|
retval = reserve_memtype(offset, offset + size, flags, NULL);
|
|
} else {
|
|
retval = reserve_memtype(offset, offset + size, -1, &flags);
|
|
}
|
|
|
|
if (retval < 0)
|
|
return 0;
|
|
|
|
if (pfn <= max_pfn_mapped &&
|
|
ioremap_change_attr((unsigned long)__va(offset), size, flags) < 0) {
|
|
free_memtype(offset, offset + size);
|
|
printk(KERN_INFO
|
|
"%s:%d /dev/mem ioremap_change_attr failed %s for %Lx-%Lx\n",
|
|
current->comm, current->pid,
|
|
cattr_name(flags),
|
|
offset, (unsigned long long)(offset + size));
|
|
return 0;
|
|
}
|
|
|
|
*vma_prot = __pgprot((pgprot_val(*vma_prot) & ~_PAGE_CACHE_MASK) |
|
|
flags);
|
|
return 1;
|
|
}
|
|
|
|
void map_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
|
|
{
|
|
u64 addr = (u64)pfn << PAGE_SHIFT;
|
|
unsigned long flags;
|
|
unsigned long want_flags = (pgprot_val(vma_prot) & _PAGE_CACHE_MASK);
|
|
|
|
reserve_memtype(addr, addr + size, want_flags, &flags);
|
|
if (flags != want_flags) {
|
|
printk(KERN_INFO
|
|
"%s:%d /dev/mem expected mapping type %s for %Lx-%Lx, got %s\n",
|
|
current->comm, current->pid,
|
|
cattr_name(want_flags),
|
|
addr, (unsigned long long)(addr + size),
|
|
cattr_name(flags));
|
|
}
|
|
}
|
|
|
|
void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
|
|
{
|
|
u64 addr = (u64)pfn << PAGE_SHIFT;
|
|
|
|
free_memtype(addr, addr + size);
|
|
}
|