aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/mm/pat.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/mm/pat.c')
-rw-r--r--arch/x86/mm/pat.c161
1 files changed, 96 insertions, 65 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index 7b61036427df..640339ee4fb2 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -11,6 +11,7 @@
#include <linux/bootmem.h>
#include <linux/debugfs.h>
#include <linux/kernel.h>
+#include <linux/module.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/fs.h>
@@ -30,7 +31,7 @@
#ifdef CONFIG_X86_PAT
int __read_mostly pat_enabled = 1;
-void __cpuinit pat_disable(char *reason)
+void __cpuinit pat_disable(const char *reason)
{
pat_enabled = 0;
printk(KERN_INFO "%s\n", reason);
@@ -42,6 +43,11 @@ static int __init nopat(char *str)
return 0;
}
early_param("nopat", nopat);
+#else
+static inline void pat_disable(const char *reason)
+{
+ (void)reason;
+}
#endif
@@ -78,16 +84,20 @@ void pat_init(void)
if (!pat_enabled)
return;
- /* Paranoia check. */
- if (!cpu_has_pat && boot_pat_state) {
- /*
- * If this happens we are on a secondary CPU, but
- * switched to PAT on the boot CPU. We have no way to
- * undo PAT.
- */
- printk(KERN_ERR "PAT enabled, "
- "but not supported by secondary CPU\n");
- BUG();
+ if (!cpu_has_pat) {
+ if (!boot_pat_state) {
+ pat_disable("PAT not supported by CPU.");
+ return;
+ } else {
+ /*
+ * If this happens we are on a secondary CPU, but
+ * switched to PAT on the boot CPU. We have no way to
+ * undo PAT.
+ */
+ printk(KERN_ERR "PAT enabled, "
+ "but not supported by secondary CPU\n");
+ BUG();
+ }
}
/* Set PWT to Write-Combining. All other bits stay the same */
@@ -211,6 +221,33 @@ chk_conflict(struct memtype *new, struct memtype *entry, unsigned long *type)
static struct memtype *cached_entry;
static u64 cached_start;
+static int pat_pagerange_is_ram(unsigned long start, unsigned long end)
+{
+ int ram_page = 0, not_rampage = 0;
+ unsigned long page_nr;
+
+ for (page_nr = (start >> PAGE_SHIFT); page_nr < (end >> PAGE_SHIFT);
+ ++page_nr) {
+ /*
+ * For legacy reasons, physical address range in the legacy ISA
+ * region is tracked as non-RAM. This will allow users of
+ * /dev/mem to map portions of legacy ISA region, even when
+ * some of those portions are listed(or not even listed) with
+ * different e820 types(RAM/reserved/..)
+ */
+ if (page_nr >= (ISA_END_ADDRESS >> PAGE_SHIFT) &&
+ page_is_ram(page_nr))
+ ram_page = 1;
+ else
+ not_rampage = 1;
+
+ if (ram_page == not_rampage)
+ return -1;
+ }
+
+ return ram_page;
+}
+
/*
* For RAM pages, mark the pages as non WB memory type using
* PageNonWB (PG_arch_1). We allow only one set_memory_uc() or
@@ -336,20 +373,12 @@ int reserve_memtype(u64 start, u64 end, unsigned long req_type,
if (new_type)
*new_type = actual_type;
- /*
- * For legacy reasons, some parts of the physical address range in the
- * legacy 1MB region is treated as non-RAM (even when listed as RAM in
- * the e820 tables). So we will track the memory attributes of this
- * legacy 1MB region using the linear memtype_list always.
- */
- if (end >= ISA_END_ADDRESS) {
- is_range_ram = pagerange_is_ram(start, end);
- if (is_range_ram == 1)
- return reserve_ram_pages_type(start, end, req_type,
- new_type);
- else if (is_range_ram < 0)
- return -EINVAL;
- }
+ is_range_ram = pat_pagerange_is_ram(start, end);
+ if (is_range_ram == 1)
+ return reserve_ram_pages_type(start, end, req_type,
+ new_type);
+ else if (is_range_ram < 0)
+ return -EINVAL;
new = kmalloc(sizeof(struct memtype), GFP_KERNEL);
if (!new)
@@ -446,19 +475,11 @@ int free_memtype(u64 start, u64 end)
if (is_ISA_range(start, end - 1))
return 0;
- /*
- * For legacy reasons, some parts of the physical address range in the
- * legacy 1MB region is treated as non-RAM (even when listed as RAM in
- * the e820 tables). So we will track the memory attributes of this
- * legacy 1MB region using the linear memtype_list always.
- */
- if (end >= ISA_END_ADDRESS) {
- is_range_ram = pagerange_is_ram(start, end);
- if (is_range_ram == 1)
- return free_ram_pages_type(start, end);
- else if (is_range_ram < 0)
- return -EINVAL;
- }
+ is_range_ram = pat_pagerange_is_ram(start, end);
+ if (is_range_ram == 1)
+ return free_ram_pages_type(start, end);
+ else if (is_range_ram < 0)
+ return -EINVAL;
spin_lock(&memtype_lock);
list_for_each_entry(entry, &memtype_list, nd) {
@@ -614,6 +635,33 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
}
/*
+ * Change the memory type for the physial address range in kernel identity
+ * mapping space if that range is a part of identity map.
+ */
+int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
+{
+ unsigned long id_sz;
+
+ if (!pat_enabled || base >= __pa(high_memory))
+ return 0;
+
+ id_sz = (__pa(high_memory) < base + size) ?
+ __pa(high_memory) - base :
+ size;
+
+ if (ioremap_change_attr((unsigned long)__va(base), id_sz, flags) < 0) {
+ printk(KERN_INFO
+ "%s:%d ioremap_change_attr failed %s "
+ "for %Lx-%Lx\n",
+ current->comm, current->pid,
+ cattr_name(flags),
+ base, (unsigned long long)(base + size));
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/*
* Internal interface to reserve a range of physical memory with prot.
* Reserved non RAM regions only and after successful reserve_memtype,
* this func also keeps identity mapping (if any) in sync with this new prot.
@@ -622,21 +670,18 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
int strict_prot)
{
int is_ram = 0;
- int id_sz, ret;
+ int ret;
unsigned long flags;
unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
- is_ram = pagerange_is_ram(paddr, paddr + size);
+ is_ram = pat_pagerange_is_ram(paddr, paddr + size);
- if (is_ram != 0) {
- /*
- * For mapping RAM pages, drivers need to call
- * set_memory_[uc|wc|wb] directly, for reserve and free, before
- * setting up the PTE.
- */
- WARN_ON_ONCE(1);
+ /*
+ * reserve_pfn_range() doesn't support RAM pages. Maintain the current
+ * behavior with RAM pages by returning success.
+ */
+ if (is_ram != 0)
return 0;
- }
ret = reserve_memtype(paddr, paddr + size, want_flags, &flags);
if (ret)
@@ -663,23 +708,8 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
flags);
}
- /* Need to keep identity mapping in sync */
- if (paddr >= __pa(high_memory))
- return 0;
-
- id_sz = (__pa(high_memory) < paddr + size) ?
- __pa(high_memory) - paddr :
- size;
-
- if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) {
+ if (kernel_map_sync_memtype(paddr, size, flags) < 0) {
free_memtype(paddr, paddr + size);
- printk(KERN_ERR
- "%s:%d reserve_pfn_range ioremap_change_attr failed %s "
- "for %Lx-%Lx\n",
- current->comm, current->pid,
- cattr_name(flags),
- (unsigned long long)paddr,
- (unsigned long long)(paddr + size));
return -EINVAL;
}
return 0;
@@ -693,7 +723,7 @@ static void free_pfn_range(u64 paddr, unsigned long size)
{
int is_ram;
- is_ram = pagerange_is_ram(paddr, paddr + size);
+ is_ram = pat_pagerange_is_ram(paddr, paddr + size);
if (is_ram == 0)
free_memtype(paddr, paddr + size);
}
@@ -861,6 +891,7 @@ pgprot_t pgprot_writecombine(pgprot_t prot)
else
return pgprot_noncached(prot);
}
+EXPORT_SYMBOL_GPL(pgprot_writecombine);
#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.