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authorAaron Durbin <adurbin@chromium.org>2018-04-18 01:02:47 -0600
committerPatrick Georgi <pgeorgi@google.com>2018-04-26 06:55:59 +0000
commit696c642afa8558d7949a13b117066d0a732653fb (patch)
treef645e458a5447eeebc07a3a64a3e8ff0035db2c9
parentd127be102be3744b9b81036e5fa53acbddaae03b (diff)
downloadcoreboot-696c642afa8558d7949a13b117066d0a732653fb.tar.xz
cpu/x86: add limited runtime identity page mapping
When employing PAGING_IN_CACHE_AS_RAM more areas need to be mapped in at runtime. Therefore, paging_identity_map_addr() is added to support adding identity mappings. Because there are a fixed amount of pages in cache-as-ram paging only the existing paging structures can be used. As such that's a limitation on what regions and length one can map. Using util/x86/x86_page_tables.go to generate page tables will always populate all the page directory pages. Therefore, 2MiB mappings are easy to map in. BUG=b:72728953 Change-Id: Ibe33aa12972ff678d2e9b80874529380b4ce9fd7 Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/25718 Reviewed-by: Justin TerAvest <teravest@chromium.org> Reviewed-by: Furquan Shaikh <furquan@google.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
-rw-r--r--src/cpu/x86/pae/pgtbl.c214
-rw-r--r--src/include/cpu/x86/pae.h5
2 files changed, 219 insertions, 0 deletions
diff --git a/src/cpu/x86/pae/pgtbl.c b/src/cpu/x86/pae/pgtbl.c
index c272b2da1c..cf6bf16413 100644
--- a/src/cpu/x86/pae/pgtbl.c
+++ b/src/cpu/x86/pae/pgtbl.c
@@ -15,6 +15,7 @@
#include <cbfs.h>
#include <compiler.h>
+#include <commonlib/helpers.h>
#include <console/console.h>
#include <cpu/cpu.h>
#include <arch/cpu.h>
@@ -25,6 +26,45 @@
#include <string.h>
#include <symbols.h>
+#define PDPTE_PRES (1ULL << 0)
+#define PDPTE_ADDR_MASK (~((1ULL << 12) - 1))
+
+#define PDE_PRES (1ULL << 0)
+#define PDE_RW (1ULL << 1)
+#define PDE_US (1ULL << 2)
+#define PDE_PWT (1ULL << 3)
+#define PDE_PCD (1ULL << 4)
+#define PDE_A (1ULL << 5)
+#define PDE_D (1ULL << 6) // only valid with PS=1
+#define PDE_PS (1ULL << 7)
+#define PDE_G (1ULL << 8) // only valid with PS=1
+#define PDE_PAT (1ULL << 12) // only valid with PS=1
+#define PDE_XD (1ULL << 63)
+#define PDE_ADDR_MASK (~((1ULL << 12) - 1))
+
+#define PTE_PRES (1ULL << 0)
+#define PTE_RW (1ULL << 1)
+#define PTE_US (1ULL << 2)
+#define PTE_PWT (1ULL << 3)
+#define PTE_PCD (1ULL << 4)
+#define PTE_A (1ULL << 5)
+#define PTE_D (1ULL << 6)
+#define PTE_PAT (1ULL << 7)
+#define PTE_G (1ULL << 8)
+#define PTE_XD (1ULL << 63)
+
+#define PDPTE_IDX_SHIFT 30
+#define PDPTE_IDX_MASK 0x3
+
+#define PDE_IDX_SHIFT 21
+#define PDE_IDX_MASK 0x1ff
+
+#define PTE_IDX_SHIFT 12
+#define PTE_IDX_MASK 0x1ff
+
+static const size_t s2MiB = 2 * MiB;
+static const size_t s4KiB = 4 * KiB;
+
void paging_enable_pae_cr3(uintptr_t cr3)
{
/* Load the page table address */
@@ -216,3 +256,177 @@ int paging_enable_for_car(const char *pdpt_name, const char *pt_name)
return 0;
}
+
+static void *get_pdpt_addr(void)
+{
+ if (ENV_CACHE_AS_RAM)
+ return _pdpt;
+ return (void *)(uintptr_t)read_cr3();
+}
+
+static uint64_t pde_pat_flags(int pat)
+{
+ switch (pat) {
+ case PAT_UC:
+ return 0 | PDE_PCD | PDE_PWT;
+ case PAT_WC:
+ return 0 | 0 | PDE_PWT;
+ case PAT_WT:
+ return PDE_PAT | PDE_PCD | PDE_PWT;
+ case PAT_WP:
+ return PDE_PAT | 0 | PDE_PWT;
+ case PAT_WB:
+ return 0 | 0 | 0;
+ case PAT_UC_MINUS:
+ return 0 | PDE_PCD | 0;
+ default:
+ printk(BIOS_ERR, "PDE PAT defaulting to WB: %x\n", pat);
+ return pde_pat_flags(PAT_WB);
+ }
+}
+
+static uint64_t pde_page_flags(int pat)
+{
+ uint64_t flags = PDE_PS | PDE_PRES | PDE_RW | PDE_A | PDE_D;
+
+ return flags | pde_pat_flags(pat);
+}
+
+static uint64_t pte_pat_flags(int pat)
+{
+ switch (pat) {
+ case PAT_UC:
+ return 0 | PTE_PCD | PTE_PWT;
+ case PAT_WC:
+ return 0 | 0 | PTE_PWT;
+ case PAT_WT:
+ return PTE_PAT | PTE_PCD | PTE_PWT;
+ case PAT_WP:
+ return PTE_PAT | 0 | PTE_PWT;
+ case PAT_WB:
+ return 0 | 0 | 0;
+ case PAT_UC_MINUS:
+ return 0 | PTE_PCD | 0;
+ default:
+ printk(BIOS_ERR, "PTE PAT defaulting to WB: %x\n", pat);
+ return pte_pat_flags(PAT_WB);
+ }
+}
+
+static uint64_t pte_page_flags(int pat)
+{
+ uint64_t flags = PTE_PRES | PTE_RW | PTE_A | PTE_D;
+ return flags | pte_pat_flags(pat);
+}
+
+/* Identity map an address. This function does not handle splitting or adding
+ * new pages to the page tables. It's assumed all the page tables are already
+ * seeded with the correct amount and topology. */
+static int identity_map_one_page(uintptr_t base, size_t size, int pat,
+ int commit)
+{
+ uint64_t (*pdpt)[4];
+ uint64_t pdpte;
+ uint64_t (*pd)[512];
+ uint64_t pde;
+
+ pdpt = get_pdpt_addr();
+
+ pdpte = (*pdpt)[(base >> PDPTE_IDX_SHIFT) & PDPTE_IDX_MASK];
+
+ /* No page table page allocation. */
+ if (!(pdpte & PDPTE_PRES))
+ return -1;
+
+ pd = (void *)(uintptr_t)(pdpte & PDPTE_ADDR_MASK);
+
+ /* Map in a 2MiB page. */
+ if (size == s2MiB) {
+ if (!commit)
+ return 0;
+ pde = base;
+ pde |= pde_page_flags(pat);
+ (*pd)[(base >> PDE_IDX_SHIFT) & PDE_IDX_MASK] = pde;
+ return 0;
+ }
+
+ if (size == s4KiB) {
+ uint64_t (*pt)[512];
+ uint64_t pte;
+
+ pde = (*pd)[(base >> PDE_IDX_SHIFT) & PDE_IDX_MASK];
+
+ /* No page table page allocation. */
+ if (!(pde & PDE_PRES)) {
+ printk(BIOS_ERR, "Cannot allocate page table for pde %p\n",
+ (void *)base);
+ return -1;
+ }
+
+ /* No splitting pages */
+ if (pde & PDE_PS) {
+ printk(BIOS_ERR, "Cannot split pde %p\n", (void *)base);
+ return -1;
+ }
+
+ if (!commit)
+ return 0;
+
+ pt = (void *)(uintptr_t)(pde & PDE_ADDR_MASK);
+ pte = base;
+ pte |= pte_page_flags(pat);
+ (*pt)[(base >> PTE_IDX_SHIFT) & PTE_IDX_MASK] = pte;
+
+ return 0;
+ }
+
+ return -1;
+}
+
+static int _paging_identity_map_addr(uintptr_t base, size_t size, int pat,
+ int commit)
+{
+ while (size != 0) {
+ size_t map_size;
+
+ map_size = IS_ALIGNED(base, s2MiB) ? s2MiB : s4KiB;
+ map_size = MIN(size, map_size);
+
+ if (identity_map_one_page(base, map_size, pat, commit) < 0)
+ return -1;
+
+ base += map_size;
+ size -= map_size;
+ }
+
+ return 0;
+}
+
+static int paging_is_enabled(void)
+{
+ return !!(read_cr0() & CR0_PG);
+}
+
+int paging_identity_map_addr(uintptr_t base, size_t size, int pat)
+{
+ if (!paging_is_enabled()) {
+ printk(BIOS_ERR, "Paging is not enabled.\n");
+ return -1;
+ }
+
+ if (!IS_ALIGNED(base, s2MiB) && !IS_ALIGNED(base, s4KiB)) {
+ printk(BIOS_ERR, "base %p is not aligned.\n", (void *)base);
+ return -1;
+ }
+
+ if (!IS_ALIGNED(size, s2MiB) && !IS_ALIGNED(size, s4KiB)) {
+ printk(BIOS_ERR, "size %zx is not aligned.\n", size);
+ return -1;
+ }
+
+ /* First try without committing. If success commit. */
+ if (_paging_identity_map_addr(base, size, pat, 0))
+ return -1;
+
+ return _paging_identity_map_addr(base, size, pat, 1);
+}
diff --git a/src/include/cpu/x86/pae.h b/src/include/cpu/x86/pae.h
index a8b5e893fc..51e47e1e85 100644
--- a/src/include/cpu/x86/pae.h
+++ b/src/include/cpu/x86/pae.h
@@ -32,6 +32,11 @@ void paging_set_default_pat(void);
* failure. */
int paging_enable_for_car(const char *pdpt_name, const char *pt_name);
+/* Identity map the region indicated by 'base' and 'size'. Both 'base' and
+ * 'size' need to be 4KiB or 2 MiB aligned. 'pat' should be one of the
+ * PAT defines above. 0 is returned on success, < 0 on failure. */
+int paging_identity_map_addr(uintptr_t base, size_t size, int pat);
+
#define MAPPING_ERROR ((void *)0xffffffffUL)
void *map_2M_page(unsigned long page);