linux/mm/early_ioremap.c
Tom Lendacky 8f716c9b5f x86/mm: Add support to access boot related data in the clear
Boot data (such as EFI related data) is not encrypted when the system is
booted because UEFI/BIOS does not run with SME active. In order to access
this data properly it needs to be mapped decrypted.

Update early_memremap() to provide an arch specific routine to modify the
pagetable protection attributes before they are applied to the new
mapping. This is used to remove the encryption mask for boot related data.

Update memremap() to provide an arch specific routine to determine if RAM
remapping is allowed.  RAM remapping will cause an encrypted mapping to be
generated. By preventing RAM remapping, ioremap_cache() will be used
instead, which will provide a decrypted mapping of the boot related data.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: kasan-dev@googlegroups.com
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: linux-efi@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/81fb6b4117a5df6b9f2eda342f81bbef4b23d2e5.1500319216.git.thomas.lendacky@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-18 11:38:02 +02:00

303 lines
6.7 KiB
C

/*
* Provide common bits of early_ioremap() support for architectures needing
* temporary mappings during boot before ioremap() is available.
*
* This is mostly a direct copy of the x86 early_ioremap implementation.
*
* (C) Copyright 1995 1996, 2014 Linus Torvalds
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <asm/fixmap.h>
#include <asm/early_ioremap.h>
#ifdef CONFIG_MMU
static int early_ioremap_debug __initdata;
static int __init early_ioremap_debug_setup(char *str)
{
early_ioremap_debug = 1;
return 0;
}
early_param("early_ioremap_debug", early_ioremap_debug_setup);
static int after_paging_init __initdata;
pgprot_t __init __weak early_memremap_pgprot_adjust(resource_size_t phys_addr,
unsigned long size,
pgprot_t prot)
{
return prot;
}
void __init __weak early_ioremap_shutdown(void)
{
}
void __init early_ioremap_reset(void)
{
early_ioremap_shutdown();
after_paging_init = 1;
}
/*
* Generally, ioremap() is available after paging_init() has been called.
* Architectures wanting to allow early_ioremap after paging_init() can
* define __late_set_fixmap and __late_clear_fixmap to do the right thing.
*/
#ifndef __late_set_fixmap
static inline void __init __late_set_fixmap(enum fixed_addresses idx,
phys_addr_t phys, pgprot_t prot)
{
BUG();
}
#endif
#ifndef __late_clear_fixmap
static inline void __init __late_clear_fixmap(enum fixed_addresses idx)
{
BUG();
}
#endif
static void __iomem *prev_map[FIX_BTMAPS_SLOTS] __initdata;
static unsigned long prev_size[FIX_BTMAPS_SLOTS] __initdata;
static unsigned long slot_virt[FIX_BTMAPS_SLOTS] __initdata;
void __init early_ioremap_setup(void)
{
int i;
for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
if (WARN_ON(prev_map[i]))
break;
for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
slot_virt[i] = __fix_to_virt(FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*i);
}
static int __init check_early_ioremap_leak(void)
{
int count = 0;
int i;
for (i = 0; i < FIX_BTMAPS_SLOTS; i++)
if (prev_map[i])
count++;
if (WARN(count, KERN_WARNING
"Debug warning: early ioremap leak of %d areas detected.\n"
"please boot with early_ioremap_debug and report the dmesg.\n",
count))
return 1;
return 0;
}
late_initcall(check_early_ioremap_leak);
static void __init __iomem *
__early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
{
unsigned long offset;
resource_size_t last_addr;
unsigned int nrpages;
enum fixed_addresses idx;
int i, slot;
WARN_ON(system_state != SYSTEM_BOOTING);
slot = -1;
for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
if (!prev_map[i]) {
slot = i;
break;
}
}
if (WARN(slot < 0, "%s(%08llx, %08lx) not found slot\n",
__func__, (u64)phys_addr, size))
return NULL;
/* Don't allow wraparound or zero size */
last_addr = phys_addr + size - 1;
if (WARN_ON(!size || last_addr < phys_addr))
return NULL;
prev_size[slot] = size;
/*
* Mappings have to be page-aligned
*/
offset = offset_in_page(phys_addr);
phys_addr &= PAGE_MASK;
size = PAGE_ALIGN(last_addr + 1) - phys_addr;
/*
* Mappings have to fit in the FIX_BTMAP area.
*/
nrpages = size >> PAGE_SHIFT;
if (WARN_ON(nrpages > NR_FIX_BTMAPS))
return NULL;
/*
* Ok, go for it..
*/
idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
while (nrpages > 0) {
if (after_paging_init)
__late_set_fixmap(idx, phys_addr, prot);
else
__early_set_fixmap(idx, phys_addr, prot);
phys_addr += PAGE_SIZE;
--idx;
--nrpages;
}
WARN(early_ioremap_debug, "%s(%08llx, %08lx) [%d] => %08lx + %08lx\n",
__func__, (u64)phys_addr, size, slot, offset, slot_virt[slot]);
prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
return prev_map[slot];
}
void __init early_iounmap(void __iomem *addr, unsigned long size)
{
unsigned long virt_addr;
unsigned long offset;
unsigned int nrpages;
enum fixed_addresses idx;
int i, slot;
slot = -1;
for (i = 0; i < FIX_BTMAPS_SLOTS; i++) {
if (prev_map[i] == addr) {
slot = i;
break;
}
}
if (WARN(slot < 0, "early_iounmap(%p, %08lx) not found slot\n",
addr, size))
return;
if (WARN(prev_size[slot] != size,
"early_iounmap(%p, %08lx) [%d] size not consistent %08lx\n",
addr, size, slot, prev_size[slot]))
return;
WARN(early_ioremap_debug, "early_iounmap(%p, %08lx) [%d]\n",
addr, size, slot);
virt_addr = (unsigned long)addr;
if (WARN_ON(virt_addr < fix_to_virt(FIX_BTMAP_BEGIN)))
return;
offset = offset_in_page(virt_addr);
nrpages = PAGE_ALIGN(offset + size) >> PAGE_SHIFT;
idx = FIX_BTMAP_BEGIN - NR_FIX_BTMAPS*slot;
while (nrpages > 0) {
if (after_paging_init)
__late_clear_fixmap(idx);
else
__early_set_fixmap(idx, 0, FIXMAP_PAGE_CLEAR);
--idx;
--nrpages;
}
prev_map[slot] = NULL;
}
/* Remap an IO device */
void __init __iomem *
early_ioremap(resource_size_t phys_addr, unsigned long size)
{
return __early_ioremap(phys_addr, size, FIXMAP_PAGE_IO);
}
/* Remap memory */
void __init *
early_memremap(resource_size_t phys_addr, unsigned long size)
{
pgprot_t prot = early_memremap_pgprot_adjust(phys_addr, size,
FIXMAP_PAGE_NORMAL);
return (__force void *)__early_ioremap(phys_addr, size, prot);
}
#ifdef FIXMAP_PAGE_RO
void __init *
early_memremap_ro(resource_size_t phys_addr, unsigned long size)
{
pgprot_t prot = early_memremap_pgprot_adjust(phys_addr, size,
FIXMAP_PAGE_RO);
return (__force void *)__early_ioremap(phys_addr, size, prot);
}
#endif
#ifdef CONFIG_ARCH_USE_MEMREMAP_PROT
void __init *
early_memremap_prot(resource_size_t phys_addr, unsigned long size,
unsigned long prot_val)
{
return (__force void *)__early_ioremap(phys_addr, size,
__pgprot(prot_val));
}
#endif
#define MAX_MAP_CHUNK (NR_FIX_BTMAPS << PAGE_SHIFT)
void __init copy_from_early_mem(void *dest, phys_addr_t src, unsigned long size)
{
unsigned long slop, clen;
char *p;
while (size) {
slop = offset_in_page(src);
clen = size;
if (clen > MAX_MAP_CHUNK - slop)
clen = MAX_MAP_CHUNK - slop;
p = early_memremap(src & PAGE_MASK, clen + slop);
memcpy(dest, p + slop, clen);
early_memunmap(p, clen + slop);
dest += clen;
src += clen;
size -= clen;
}
}
#else /* CONFIG_MMU */
void __init __iomem *
early_ioremap(resource_size_t phys_addr, unsigned long size)
{
return (__force void __iomem *)phys_addr;
}
/* Remap memory */
void __init *
early_memremap(resource_size_t phys_addr, unsigned long size)
{
return (void *)phys_addr;
}
void __init *
early_memremap_ro(resource_size_t phys_addr, unsigned long size)
{
return (void *)phys_addr;
}
void __init early_iounmap(void __iomem *addr, unsigned long size)
{
}
#endif /* CONFIG_MMU */
void __init early_memunmap(void *addr, unsigned long size)
{
early_iounmap((__force void __iomem *)addr, size);
}