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-rw-r--r--arch/x86/mm/pat.c596
1 files changed, 596 insertions, 0 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
new file mode 100644
index 00000000000..277446cd30b
--- /dev/null
+++ b/arch/x86/mm/pat.c
@@ -0,0 +1,596 @@
+/*
+ * Handle caching attributes in page tables (PAT)
+ *
+ * Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ * Suresh B Siddha <suresh.b.siddha@intel.com>
+ *
+ * Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen.
+ */
+
+#include <linux/mm.h>
+#include <linux/kernel.h>
+#include <linux/gfp.h>
+#include <linux/fs.h>
+#include <linux/bootmem.h>
+
+#include <asm/msr.h>
+#include <asm/tlbflush.h>
+#include <asm/processor.h>
+#include <asm/page.h>
+#include <asm/pgtable.h>
+#include <asm/pat.h>
+#include <asm/e820.h>
+#include <asm/cacheflush.h>
+#include <asm/fcntl.h>
+#include <asm/mtrr.h>
+#include <asm/io.h>
+
+int pat_wc_enabled = 1;
+
+static u64 __read_mostly boot_pat_state;
+
+static int nopat(char *str)
+{
+ pat_wc_enabled = 0;
+ printk(KERN_INFO "x86: PAT support disabled.\n");
+
+ return 0;
+}
+early_param("nopat", nopat);
+
+static int pat_known_cpu(void)
+{
+ if (!pat_wc_enabled)
+ return 0;
+
+ if (cpu_has_pat)
+ return 1;
+
+ pat_wc_enabled = 0;
+ printk(KERN_INFO "CPU and/or kernel does not support PAT.\n");
+ return 0;
+}
+
+enum {
+ PAT_UC = 0, /* uncached */
+ PAT_WC = 1, /* Write combining */
+ PAT_WT = 4, /* Write Through */
+ PAT_WP = 5, /* Write Protected */
+ PAT_WB = 6, /* Write Back (default) */
+ PAT_UC_MINUS = 7, /* UC, but can be overriden by MTRR */
+};
+
+#define PAT(x,y) ((u64)PAT_ ## y << ((x)*8))
+
+void pat_init(void)
+{
+ u64 pat;
+
+#ifndef CONFIG_X86_PAT
+ nopat(NULL);
+#endif
+
+ /* Boot CPU enables PAT based on CPU feature */
+ if (!smp_processor_id() && !pat_known_cpu())
+ return;
+
+ /* APs enable PAT iff boot CPU has enabled it before */
+ if (smp_processor_id() && !pat_wc_enabled)
+ return;
+
+ /* Set PWT to Write-Combining. All other bits stay the same */
+ /*
+ * PTE encoding used in Linux:
+ * PAT
+ * |PCD
+ * ||PWT
+ * |||
+ * 000 WB _PAGE_CACHE_WB
+ * 001 WC _PAGE_CACHE_WC
+ * 010 UC- _PAGE_CACHE_UC_MINUS
+ * 011 UC _PAGE_CACHE_UC
+ * PAT bit unused
+ */
+ pat = PAT(0,WB) | PAT(1,WC) | PAT(2,UC_MINUS) | PAT(3,UC) |
+ PAT(4,WB) | PAT(5,WC) | PAT(6,UC_MINUS) | PAT(7,UC);
+
+ /* Boot CPU check */
+ if (!smp_processor_id()) {
+ rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
+ }
+
+ wrmsrl(MSR_IA32_CR_PAT, pat);
+ printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n",
+ smp_processor_id(), boot_pat_state, pat);
+}
+
+#undef PAT
+
+static char *cattr_name(unsigned long flags)
+{
+ switch (flags & _PAGE_CACHE_MASK) {
+ case _PAGE_CACHE_UC: return "uncached";
+ case _PAGE_CACHE_UC_MINUS: return "uncached-minus";
+ case _PAGE_CACHE_WB: return "write-back";
+ case _PAGE_CACHE_WC: return "write-combining";
+ default: return "broken";
+ }
+}
+
+/*
+ * The global memtype list keeps track of memory type for specific
+ * physical memory areas. Conflicting memory types in different
+ * mappings can cause CPU cache corruption. To avoid this we keep track.
+ *
+ * The list is sorted based on starting address and can contain multiple
+ * entries for each address (this allows reference counting for overlapping
+ * areas). All the aliases have the same cache attributes of course.
+ * Zero attributes are represented as holes.
+ *
+ * Currently the data structure is a list because the number of mappings
+ * are expected to be relatively small. If this should be a problem
+ * it could be changed to a rbtree or similar.
+ *
+ * memtype_lock protects the whole list.
+ */
+
+struct memtype {
+ u64 start;
+ u64 end;
+ unsigned long type;
+ struct list_head nd;
+};
+
+static LIST_HEAD(memtype_list);
+static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */
+
+/*
+ * Does intersection of PAT memory type and MTRR memory type and returns
+ * the resulting memory type as PAT understands it.
+ * (Type in pat and mtrr will not have same value)
+ * The intersection is based on "Effective Memory Type" tables in IA-32
+ * SDM vol 3a
+ */
+static int pat_x_mtrr_type(u64 start, u64 end, unsigned long prot,
+ unsigned long *ret_prot)
+{
+ unsigned long pat_type;
+ u8 mtrr_type;
+
+ mtrr_type = mtrr_type_lookup(start, end);
+ if (mtrr_type == 0xFF) { /* MTRR not enabled */
+ *ret_prot = prot;
+ return 0;
+ }
+ if (mtrr_type == 0xFE) { /* MTRR match error */
+ *ret_prot = _PAGE_CACHE_UC;
+ return -1;
+ }
+ if (mtrr_type != MTRR_TYPE_UNCACHABLE &&
+ mtrr_type != MTRR_TYPE_WRBACK &&
+ mtrr_type != MTRR_TYPE_WRCOMB) { /* MTRR type unhandled */
+ *ret_prot = _PAGE_CACHE_UC;
+ return -1;
+ }
+
+ pat_type = prot & _PAGE_CACHE_MASK;
+ prot &= (~_PAGE_CACHE_MASK);
+
+ /* Currently doing intersection by hand. Optimize it later. */
+ if (pat_type == _PAGE_CACHE_WC) {
+ *ret_prot = prot | _PAGE_CACHE_WC;
+ } else if (pat_type == _PAGE_CACHE_UC_MINUS) {
+ *ret_prot = prot | _PAGE_CACHE_UC_MINUS;
+ } else if (pat_type == _PAGE_CACHE_UC ||
+ mtrr_type == MTRR_TYPE_UNCACHABLE) {
+ *ret_prot = prot | _PAGE_CACHE_UC;
+ } else if (mtrr_type == MTRR_TYPE_WRCOMB) {
+ *ret_prot = prot | _PAGE_CACHE_WC;
+ } else {
+ *ret_prot = prot | _PAGE_CACHE_WB;
+ }
+
+ return 0;
+}
+
+/*
+ * req_type typically has one of the:
+ * - _PAGE_CACHE_WB
+ * - _PAGE_CACHE_WC
+ * - _PAGE_CACHE_UC_MINUS
+ * - _PAGE_CACHE_UC
+ *
+ * req_type will have a special case value '-1', when requester want to inherit
+ * the memory type from mtrr (if WB), existing PAT, defaulting to UC_MINUS.
+ *
+ * If ret_type is NULL, function will return an error if it cannot reserve the
+ * region with req_type. If ret_type is non-null, function will return
+ * available type in ret_type in case of no error. In case of any error
+ * it will return a negative return value.
+ */
+int reserve_memtype(u64 start, u64 end, unsigned long req_type,
+ unsigned long *ret_type)
+{
+ struct memtype *new_entry = NULL;
+ struct memtype *parse;
+ unsigned long actual_type;
+ int err = 0;
+
+ /* Only track when pat_wc_enabled */
+ if (!pat_wc_enabled) {
+ /* This is identical to page table setting without PAT */
+ if (ret_type) {
+ if (req_type == -1) {
+ *ret_type = _PAGE_CACHE_WB;
+ } else {
+ *ret_type = req_type;
+ }
+ }
+ return 0;
+ }
+
+ /* Low ISA region is always mapped WB in page table. No need to track */
+ if (start >= ISA_START_ADDRESS && (end - 1) <= ISA_END_ADDRESS) {
+ if (ret_type)
+ *ret_type = _PAGE_CACHE_WB;
+
+ return 0;
+ }
+
+ if (req_type == -1) {
+ /*
+ * Special case where caller wants to inherit from mtrr or
+ * existing pat mapping, defaulting to UC_MINUS in case of
+ * no match.
+ */
+ u8 mtrr_type = mtrr_type_lookup(start, end);
+ if (mtrr_type == 0xFE) { /* MTRR match error */
+ err = -1;
+ }
+
+ if (mtrr_type == MTRR_TYPE_WRBACK) {
+ req_type = _PAGE_CACHE_WB;
+ actual_type = _PAGE_CACHE_WB;
+ } else {
+ req_type = _PAGE_CACHE_UC_MINUS;
+ actual_type = _PAGE_CACHE_UC_MINUS;
+ }
+ } else {
+ req_type &= _PAGE_CACHE_MASK;
+ err = pat_x_mtrr_type(start, end, req_type, &actual_type);
+ }
+
+ if (err) {
+ if (ret_type)
+ *ret_type = actual_type;
+
+ return -EINVAL;
+ }
+
+ new_entry = kmalloc(sizeof(struct memtype), GFP_KERNEL);
+ if (!new_entry)
+ return -ENOMEM;
+
+ new_entry->start = start;
+ new_entry->end = end;
+ new_entry->type = actual_type;
+
+ if (ret_type)
+ *ret_type = actual_type;
+
+ spin_lock(&memtype_lock);
+
+ /* Search for existing mapping that overlaps the current range */
+ list_for_each_entry(parse, &memtype_list, nd) {
+ struct memtype *saved_ptr;
+
+ if (parse->start >= end) {
+ pr_debug("New Entry\n");
+ list_add(&new_entry->nd, parse->nd.prev);
+ new_entry = NULL;
+ break;
+ }
+
+ if (start <= parse->start && end >= parse->start) {
+ if (actual_type != parse->type && ret_type) {
+ actual_type = parse->type;
+ *ret_type = actual_type;
+ new_entry->type = actual_type;
+ }
+
+ if (actual_type != parse->type) {
+ printk(
+ KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
+ current->comm, current->pid,
+ start, end,
+ cattr_name(actual_type),
+ cattr_name(parse->type));
+ err = -EBUSY;
+ break;
+ }
+
+ saved_ptr = parse;
+ /*
+ * Check to see whether the request overlaps more
+ * than one entry in the list
+ */
+ list_for_each_entry_continue(parse, &memtype_list, nd) {
+ if (end <= parse->start) {
+ break;
+ }
+
+ if (actual_type != parse->type) {
+ printk(
+ KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
+ current->comm, current->pid,
+ start, end,
+ cattr_name(actual_type),
+ cattr_name(parse->type));
+ err = -EBUSY;
+ break;
+ }
+ }
+
+ if (err) {
+ break;
+ }
+
+ pr_debug("Overlap at 0x%Lx-0x%Lx\n",
+ saved_ptr->start, saved_ptr->end);
+ /* No conflict. Go ahead and add this new entry */
+ list_add(&new_entry->nd, saved_ptr->nd.prev);
+ new_entry = NULL;
+ break;
+ }
+
+ if (start < parse->end) {
+ if (actual_type != parse->type && ret_type) {
+ actual_type = parse->type;
+ *ret_type = actual_type;
+ new_entry->type = actual_type;
+ }
+
+ if (actual_type != parse->type) {
+ printk(
+ KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
+ current->comm, current->pid,
+ start, end,
+ cattr_name(actual_type),
+ cattr_name(parse->type));
+ err = -EBUSY;
+ break;
+ }
+
+ saved_ptr = parse;
+ /*
+ * Check to see whether the request overlaps more
+ * than one entry in the list
+ */
+ list_for_each_entry_continue(parse, &memtype_list, nd) {
+ if (end <= parse->start) {
+ break;
+ }
+
+ if (actual_type != parse->type) {
+ printk(
+ KERN_INFO "%s:%d conflicting memory types %Lx-%Lx %s<->%s\n",
+ current->comm, current->pid,
+ start, end,
+ cattr_name(actual_type),
+ cattr_name(parse->type));
+ err = -EBUSY;
+ break;
+ }
+ }
+
+ if (err) {
+ break;
+ }
+
+ pr_debug(KERN_INFO "Overlap at 0x%Lx-0x%Lx\n",
+ saved_ptr->start, saved_ptr->end);
+ /* No conflict. Go ahead and add this new entry */
+ list_add(&new_entry->nd, &saved_ptr->nd);
+ new_entry = NULL;
+ break;
+ }
+ }
+
+ if (err) {
+ printk(KERN_INFO
+ "reserve_memtype failed 0x%Lx-0x%Lx, track %s, req %s\n",
+ start, end, cattr_name(new_entry->type),
+ cattr_name(req_type));
+ kfree(new_entry);
+ spin_unlock(&memtype_lock);
+ return err;
+ }
+
+ if (new_entry) {
+ /* No conflict. Not yet added to the list. Add to the tail */
+ list_add_tail(&new_entry->nd, &memtype_list);
+ pr_debug("New Entry\n");
+ }
+
+ if (ret_type) {
+ pr_debug(
+ "reserve_memtype added 0x%Lx-0x%Lx, track %s, req %s, ret %s\n",
+ start, end, cattr_name(actual_type),
+ cattr_name(req_type), cattr_name(*ret_type));
+ } else {
+ pr_debug(
+ "reserve_memtype added 0x%Lx-0x%Lx, track %s, req %s\n",
+ start, end, cattr_name(actual_type),
+ cattr_name(req_type));
+ }
+
+ spin_unlock(&memtype_lock);
+ return err;
+}
+
+int free_memtype(u64 start, u64 end)
+{
+ struct memtype *ml;
+ int err = -EINVAL;
+
+ /* Only track when pat_wc_enabled */
+ if (!pat_wc_enabled) {
+ return 0;
+ }
+
+ /* Low ISA region is always mapped WB. No need to track */
+ if (start >= ISA_START_ADDRESS && end <= ISA_END_ADDRESS) {
+ return 0;
+ }
+
+ spin_lock(&memtype_lock);
+ list_for_each_entry(ml, &memtype_list, nd) {
+ if (ml->start == start && ml->end == end) {
+ list_del(&ml->nd);
+ kfree(ml);
+ err = 0;
+ break;
+ }
+ }
+ spin_unlock(&memtype_lock);
+
+ if (err) {
+ printk(KERN_INFO "%s:%d freeing invalid memtype %Lx-%Lx\n",
+ current->comm, current->pid, start, end);
+ }
+
+ pr_debug("free_memtype request 0x%Lx-0x%Lx\n", start, end);
+ return err;
+}
+
+
+/*
+ * /dev/mem mmap interface. The memtype used for mapping varies:
+ * - Use UC for mappings with O_SYNC flag
+ * - Without O_SYNC flag, if there is any conflict in reserve_memtype,
+ * inherit the memtype from existing mapping.
+ * - Else use UC_MINUS memtype (for backward compatibility with existing
+ * X drivers.
+ */
+pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
+ unsigned long size, pgprot_t vma_prot)
+{
+ return vma_prot;
+}
+
+#ifdef CONFIG_NONPROMISC_DEVMEM
+/* This check is done in drivers/char/mem.c in case of NONPROMISC_DEVMEM*/
+static inline int range_is_allowed(unsigned long pfn, unsigned long size)
+{
+ return 1;
+}
+#else
+static inline int range_is_allowed(unsigned long pfn, unsigned long size)
+{
+ u64 from = ((u64)pfn) << PAGE_SHIFT;
+ u64 to = from + size;
+ u64 cursor = from;
+
+ while (cursor < to) {
+ if (!devmem_is_allowed(pfn)) {
+ printk(KERN_INFO
+ "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
+ current->comm, from, to);
+ return 0;
+ }
+ cursor += PAGE_SIZE;
+ pfn++;
+ }
+ return 1;
+}
+#endif /* CONFIG_NONPROMISC_DEVMEM */
+
+int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
+ unsigned long size, pgprot_t *vma_prot)
+{
+ u64 offset = ((u64) pfn) << PAGE_SHIFT;
+ unsigned long flags = _PAGE_CACHE_UC_MINUS;
+ int retval;
+
+ if (!range_is_allowed(pfn, size))
+ return 0;
+
+ if (file->f_flags & O_SYNC) {
+ flags = _PAGE_CACHE_UC;
+ }
+
+#ifdef CONFIG_X86_32
+ /*
+ * On the PPro and successors, the MTRRs are used to set
+ * memory types for physical addresses outside main memory,
+ * so blindly setting UC or PWT on those pages is wrong.
+ * For Pentiums and earlier, the surround logic should disable
+ * caching for the high addresses through the KEN pin, but
+ * we maintain the tradition of paranoia in this code.
+ */
+ if (!pat_wc_enabled &&
+ ! ( test_bit(X86_FEATURE_MTRR, boot_cpu_data.x86_capability) ||
+ test_bit(X86_FEATURE_K6_MTRR, boot_cpu_data.x86_capability) ||
+ test_bit(X86_FEATURE_CYRIX_ARR, boot_cpu_data.x86_capability) ||
+ test_bit(X86_FEATURE_CENTAUR_MCR, boot_cpu_data.x86_capability)) &&
+ (pfn << PAGE_SHIFT) >= __pa(high_memory)) {
+ flags = _PAGE_CACHE_UC;
+ }
+#endif
+
+ /*
+ * With O_SYNC, we can only take UC mapping. Fail if we cannot.
+ * Without O_SYNC, we want to get
+ * - WB for WB-able memory and no other conflicting mappings
+ * - UC_MINUS for non-WB-able memory with no other conflicting mappings
+ * - Inherit from confliting mappings otherwise
+ */
+ 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, 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, 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);
+}
+
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2024-12-26 01:16:57 +0000