cpu/x86/64bit: Generate static page tables from an assembly file
This removes the need for a tool to generate simple identity pages.
Future patches will link this page table directly into the stages on
some platforms so having an assembly file makes a lot of sense.
This also optimizes the size of the page of each 4K page by placing
the PDPE_table below the PDE.
Change-Id: Ia1e31b701a2584268c85d327bf139953213899e3
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/63725
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
diff --git a/Documentation/arch/x86/index.md b/Documentation/arch/x86/index.md
index a30c5e2..c7115b4 100644
--- a/Documentation/arch/x86/index.md
+++ b/Documentation/arch/x86/index.md
@@ -26,9 +26,7 @@
* A stage can install new page tables in RAM
## Page tables
-Page tables are generated by a tool in `util/pgtblgen/pgtblgen`. It writes
-the page tables to a file which is then included into the CBFS as file called
-`pagetables`.
+A `pagetables` cbfs file is generated based on an assembly file.
To generate the static page tables it must know the physical address where to
place the file.
diff --git a/src/cpu/x86/64bit/Makefile.inc b/src/cpu/x86/64bit/Makefile.inc
index 721e620..1895498 100644
--- a/src/cpu/x86/64bit/Makefile.inc
+++ b/src/cpu/x86/64bit/Makefile.inc
@@ -5,3 +5,15 @@
romstage-y += mode_switch.S
postcar-y += mode_switch.S
ramstage-y += mode_switch.S
+
+# Add --defsym=_start=0 to suppress a linker warning.
+$(objcbfs)/pt: $(dir)/pt.S
+ $(CC_bootblock) $(CFLAGS_bootblock) $(CPPFLAGS_bootblock) -o $@.tmp $< -Wl,--section-start=.rodata=$(CONFIG_ARCH_X86_64_PGTBL_LOC),--defsym=_start=0
+ $(OBJCOPY_ramstage) -Obinary -j .rodata $@.tmp $@
+ rm $@.tmp
+
+cbfs-files-y += pagetables
+pagetables-file := $(objcbfs)/pt
+pagetables-type := raw
+pagetables-compression := none
+pagetables-COREBOOT-position := $(CONFIG_ARCH_X86_64_PGTBL_LOC)
diff --git a/src/cpu/x86/64bit/pt.S b/src/cpu/x86/64bit/pt.S
new file mode 100644
index 0000000..b105528
--- /dev/null
+++ b/src/cpu/x86/64bit/pt.S
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * For reference see "AMD64 Architecture Programmer's Manual Volume 2",
+ * Document 24593-Rev. 3.31-July 2019 Chapter 5.3.4
+ *
+ * Page table attributes: WB, User+Supervisor, Present, Writeable, Accessed, Dirty
+ */
+
+.section .rodata
+#define _PRES (1ULL << 0)
+#define _RW (1ULL << 1)
+#define _US (1ULL << 2)
+#define _A (1ULL << 5)
+#define _D (1ULL << 6)
+#define _PS (1ULL << 7)
+#define _GEN_DIR(a) (_PRES + _RW + _US + _A + (a))
+#define _GEN_PAGE(a) (_PRES + _RW + _US + _PS + _A + _D + (a))
+
+.global PM4LE
+.align 32
+PM4LE:
+.quad _GEN_DIR(PDPE_table)
+
+.align 4096
+PDE_tables: /* identity map 2MiB pages */
+.rept 2048
+.quad _GEN_PAGE(0x200000 * ((. - PDE_tables) >> 3))
+.endr
+
+.align 4096
+PDPE_table: /* Point to PDE */
+.rept 4
+.quad _GEN_DIR(PDE_tables + 4096 * ((. - PDPE_table) >> 3))
+.endr
diff --git a/util/pgtblgen/Makefile.inc b/util/pgtblgen/Makefile.inc
deleted file mode 100644
index 08fb620..0000000
--- a/util/pgtblgen/Makefile.inc
+++ /dev/null
@@ -1,19 +0,0 @@
-ifeq ($(CONFIG_ARCH_BOOTBLOCK_X86_64),y)
-
-PGTBLGEN:= $(obj)/pgtblgen
-
-cbfs-files-y += pagetables
-pagetables-file := $(obj)/mainboard/$(MAINBOARDDIR)/pagetables
-pagetables-type := raw
-pagetables-compression := none
-pagetables-COREBOOT-position := $(CONFIG_ARCH_X86_64_PGTBL_LOC)
-
-$(obj)/mainboard/$(MAINBOARDDIR)/pagetables: $(PGTBLGEN) $(obj)/config.h
- printf " TOOL Creating page tables\n"
- $(PGTBLGEN) -b $(CONFIG_ARCH_X86_64_PGTBL_LOC) -a x86_64 -o $@
-
-$(PGTBLGEN): util/pgtblgen/pgtblgen.c
- printf " MAKE Creating PGTBLGEN tool\n"
- $(HOSTCC) -std=c99 $< -I$(obj) -o $@
-
-endif
diff --git a/util/pgtblgen/description.md b/util/pgtblgen/description.md
deleted file mode 100644
index f2e4763..0000000
--- a/util/pgtblgen/description.md
+++ /dev/null
@@ -1 +0,0 @@
-Generates page tables based on fixed physical address. `C`
diff --git a/util/pgtblgen/pgtblgen.c b/util/pgtblgen/pgtblgen.c
deleted file mode 100644
index 7ed98b2..0000000
--- a/util/pgtblgen/pgtblgen.c
+++ /dev/null
@@ -1,158 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <errno.h>
-#include <inttypes.h>
-#include <getopt.h>
-
-static void usage(char *argv[])
-{
- printf("usage: %s -b <addr> -a <arch> -o <file>\n", argv[0]);
- printf(" -a\t architecture. Supported: x86_64\n");
- printf(" -b\t base address\n");
- printf(" -o\t the file to write to\n");
- printf(" -h\t show this help text\n");
-}
-
-/*
- * For reference see "AMD64 ArchitectureProgrammer's Manual Volume 2",
- * Document 24593-Rev. 3.31-July 2019 Chapter 5.3.4
- *
- * Page table attributes: WB, User+Supervisor, Present, Writeable, Accessed, Dirty
- */
-#define _PRES (1ULL << 0)
-#define _RW (1ULL << 1)
-#define _US (1ULL << 2)
-#define _A (1ULL << 5)
-#define _D (1ULL << 6)
-#define _PS (1ULL << 7)
-#define _GEN_DIR(a) (_PRES | _RW | _US | _A | (a))
-#define _GEN_PAGE(a) (_PRES | _RW | _US | _PS | _A | _D | (a))
-
-/*
- * Generate x86_64 page tables.
- * The page tables needs to be placed at @base_address, and identity map
- * the first @size_gib GiB of physical memory.
- */
-static int gen_pgtbl_x86_64(const uint64_t base_address,
- const size_t size_gib,
- void **out_buf,
- size_t *out_size)
-{
- uint64_t *entry;
-
- if (!out_size || !out_buf)
- return 1;
-
- *out_size = (size_gib + 2) * 4096;
- *out_buf = malloc(*out_size);
- if (!*out_buf)
- return 1;
-
- memset(*out_buf, 0, *out_size);
- entry = (uint64_t *)*out_buf;
-
- /* Generate one PM4LE entry - point to PDPE */
- entry[0] = _GEN_DIR(base_address + 4096);
- entry += 512;
-
- /* PDPE table - point to PDE */
- for (size_t i = 0; i < size_gib; i++)
- entry[i] = _GEN_DIR(base_address + 4096 * (i + 2));
- entry += 512;
-
- /* PDE tables - identity map 2MiB pages */
- for (size_t g = 0; g < size_gib; g++) {
- for (size_t i = 0; i < 512; i++) {
- uint64_t addr = ((1ULL << (12 + 9)) * i) | ((1ULL << (12 + 9 + 9)) * g);
- entry[i] = _GEN_PAGE(addr);
- }
- entry += 512;
- }
-
- return 0;
-}
-
-int main(int argc, char *argv[])
-{
- int ret = 1;
- uint64_t base_address = 0;
- char *filename = NULL;
- char *arch = NULL;
- void *buf = NULL;
- size_t buf_size = 0;
- int c;
-
- while ((c = getopt(argc, argv, "ho:a:b:")) != -1)
- switch (c) {
- case '?': /* falltrough */
- case 'h':
- usage(argv);
- return 0;
- case 'o':
- filename = optarg;
- break;
- case 'a':
- arch = optarg;
- break;
- case 'b':
- base_address = strtoull(optarg, NULL, 0);
- break;
- default:
- break;
- }
-
- if (!filename) {
- fprintf(stderr, "E: Missing filename.\n");
- goto done;
- }
- if (!arch) {
- fprintf(stderr, "E: Missing architecture.\n");
- goto done;
- } else if (strcmp(arch, "x86_64") != 0) {
- fprintf(stderr, "E: Unsupported architecture.\n");
- goto done;
- }
- if (base_address & 4095) {
- fprintf(stderr, "E: Base address not 4 KiB aligned\n");
- goto done;
- }
-
- /* FIXME: Identity map 4GiB for now, increase if necessary */
- if (strcmp(arch, "x86_64") == 0)
- ret = gen_pgtbl_x86_64(base_address, 4, &buf, &buf_size);
-
- if (ret) {
- fprintf(stderr, "Failed to generate page tables\n");
- goto done;
- }
-
- // write the table
- FILE *fd = fopen(filename, "wb");
- if (!fd) {
- fprintf(stderr, "%s open failed: %s\n", filename, strerror(errno));
- goto done;
- }
-
- if (fwrite(buf, 1, buf_size, fd) != buf_size) {
- fprintf(stderr, "%s write failed: %s\n", filename, strerror(errno));
- fclose(fd);
- goto done;
- }
-
- if (fclose(fd)) {
- fprintf(stderr, "%s close failed: %s\n", filename, strerror(errno));
- goto done;
- }
-
- ret = 0;
-done:
- free(buf);
- return ret;
-}