[PATCH 3/5] bsps/x86_64: Add paging support with 1GiB super pages
Amaan Cheval
amaan.cheval at gmail.com
Mon Aug 13 11:27:22 UTC 2018
Updates #2898.
---
bsps/x86_64/amd64/start/bspstart.c | 2 +
bsps/x86_64/amd64/start/page.c | 172 ++++++++++++++++++
bsps/x86_64/headers.am | 5 +
bsps/x86_64/include/libcpu/page.h | 68 +++++++
c/src/lib/libbsp/x86_64/amd64/Makefile.am | 1 +
.../cpu/x86_64/include/rtems/score/cpu_asm.h | 13 ++
6 files changed, 261 insertions(+)
create mode 100644 bsps/x86_64/amd64/start/page.c
create mode 100644 bsps/x86_64/headers.am
create mode 100644 bsps/x86_64/include/libcpu/page.h
diff --git a/bsps/x86_64/amd64/start/bspstart.c b/bsps/x86_64/amd64/start/bspstart.c
index 784748ce3f..5a5b46bcec 100644
--- a/bsps/x86_64/amd64/start/bspstart.c
+++ b/bsps/x86_64/amd64/start/bspstart.c
@@ -26,7 +26,9 @@
#include <bsp.h>
#include <bsp/bootcard.h>
+#include <libcpu/page.h>
void bsp_start(void)
{
+ paging_init();
}
diff --git a/bsps/x86_64/amd64/start/page.c b/bsps/x86_64/amd64/start/page.c
new file mode 100644
index 0000000000..64bdf21707
--- /dev/null
+++ b/bsps/x86_64/amd64/start/page.c
@@ -0,0 +1,172 @@
+/*
+ * This file sets up page sizes to 1GiB (i.e. huge pages, using only the PML4
+ * and PDPT, skipping the PDT, and PT).
+ * We set up identity-page mapping for the 512 GiBs addressable by using static
+ * PML4 and PDPT tables.
+ *
+ * Section 4.5 "4-Level Paging" of Volume 3 of the Intel Software Developer
+ * Manual guides a lot of the code used in this file.
+ */
+
+/*
+ * Copyright (c) 2018.
+ * Amaan Cheval <amaan.cheval at gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdio.h>
+#include <assert.h>
+#include <bsp.h>
+#include <rtems.h>
+#include <libcpu/page.h>
+#include <rtems/score/cpu.h>
+
+uint64_t amd64_pml4[NUM_PAGE_TABLE_ENTRIES] RTEMS_ALIGNED(4096);
+uint64_t amd64_pdpt[NUM_PAGE_TABLE_ENTRIES] RTEMS_ALIGNED(4096);
+
+bool paging_1gib_pages_supported(void)
+{
+ /*
+ * If CPUID.80000001H:EDX.Page1GB [bit 26] = 1, 1-GByte pages are supported
+ * with 4-level paging.
+ */
+ uint32_t a, b, c, d;
+ cpuid(0x80000001, &a, &b, &c, &d);
+ return (d >> 26) & 1;
+}
+
+uint8_t get_maxphysaddr(void)
+{
+ /*
+ * CPUID.80000008H:EAX[15:8] reports the linear-address width supported by the
+ * processor. Generally, this value is 48 if CPUID.80000001H:EDX.LM [bit 29] =
+ * 1 and 32 otherwise.
+ */
+ uint32_t a, b, c, d;
+ cpuid(0x80000008, &a, &b, &c, &d);
+
+ uint8_t maxphysaddr = (a >> 8) & 0xff;
+ /* This width is referred to as MAXPHYADDR. MAXPHYADDR is at most 52. */
+ assert(maxphysaddr <= 52);
+
+ return maxphysaddr;
+}
+
+uint64_t get_mask_for_bits(uint8_t start, uint8_t end)
+{
+ /*
+ * Create a mask that lets you select bits start:end when logically ANDed with
+ * a value. For eg.
+ * get_mask_for_bits(48, 64) = 0xffff000000000000
+ */
+ uint64_t mask = (((uint64_t) 1 << (end - start)) - 1) << start;
+ return mask;
+}
+
+RTEMS_INLINE_ROUTINE void assert_0s_from_bit(uint64_t entry, uint8_t bit_pos)
+{
+ /* Confirm that bit_pos:64 are all 0s */
+ assert((entry & get_mask_for_bits(bit_pos, 64)) == 0);
+}
+
+uint64_t create_cr3_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+)
+{
+ /* Confirm PML4 address is aligned on a 4KiB boundary */
+ assert((phys_addr & 0xfff) == 0);
+ uint64_t entry = (phys_addr & get_mask_for_bits(12, maxphysaddr)) | flags;
+
+ /* Confirm that bits maxphysaddr:64 are 0s */
+ assert_0s_from_bit(entry, maxphysaddr);
+ return entry;
+}
+
+uint64_t create_pml4_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+)
+{
+ /* Confirm address we're writing is aligned on a 4KiB boundary */
+ assert((phys_addr & 0xfff) == 0);
+ uint64_t entry = (phys_addr & get_mask_for_bits(12, maxphysaddr)) | flags;
+
+ /*
+ * Confirm that bits maxphysaddr:64 are 0s; there are other usable bits there
+ * such as PAGE_FLAGS_NO_EXECUTE, but we're asserting that those aren't set
+ * either.
+ */
+ assert_0s_from_bit(entry, maxphysaddr);
+ return entry;
+}
+
+uint64_t create_pdpt_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+)
+{
+ /* Confirm physical address is a 1GiB aligned page address */
+ assert((phys_addr & 0x3fffffff) == 0);
+ uint64_t entry = (phys_addr & get_mask_for_bits(30, maxphysaddr)) | flags;
+
+ /*
+ * Confirm that bits maxphysaddr:64 are 0s; there are other usable bits there
+ * such as the protection key and PAGE_FLAGS_NO_EXECUTE, but we're asserting
+ * that those aren't set either.
+ */
+ assert_0s_from_bit(entry, maxphysaddr);
+ return entry;
+}
+
+void paging_init(void)
+{
+ if ( !paging_1gib_pages_supported() ) {
+ printf("warning: 1 GiB pages aren't supported - trying anyway.\n");
+ }
+ const uint8_t maxphysaddr = get_maxphysaddr();
+ DBG_PRINTF("maxphysaddr = %d\n", maxphysaddr);
+
+ const uint64_t gib = (1 << 30);
+
+ for (uint32_t i = 0; i < NUM_PAGE_TABLE_ENTRIES; i++) {
+ amd64_pdpt[i] = create_pdpt_entry(
+ /* This is the i-th GiB for identity-mapping */
+ (uint64_t) i * gib,
+ maxphysaddr,
+ /* Setting huge page in the PDPTE gives us 1 GiB pages */
+ PAGE_FLAGS_DEFAULTS | PAGE_FLAGS_HUGE_PAGE
+ );
+
+ amd64_pml4[i] = create_pml4_entry(
+ (uint64_t) amd64_pdpt,
+ maxphysaddr,
+ PAGE_FLAGS_DEFAULTS
+ );
+ }
+
+ amd64_set_cr3(
+ create_cr3_entry(
+ (uint64_t) &amd64_pml4,
+ maxphysaddr,
+ PAGE_FLAGS_WRITE_THROUGH
+ )
+ );
+}
diff --git a/bsps/x86_64/headers.am b/bsps/x86_64/headers.am
new file mode 100644
index 0000000000..6f79bca7c0
--- /dev/null
+++ b/bsps/x86_64/headers.am
@@ -0,0 +1,5 @@
+## This file was generated by "./boostrap -H".
+
+include_libcpudir = $(includedir)/libcpu
+include_libcpu_HEADERS =
+include_libcpu_HEADERS += ../../../../../bsps/x86_64/include/libcpu/page.h
diff --git a/bsps/x86_64/include/libcpu/page.h b/bsps/x86_64/include/libcpu/page.h
new file mode 100644
index 0000000000..1903ae975e
--- /dev/null
+++ b/bsps/x86_64/include/libcpu/page.h
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2018.
+ * Amaan Cheval <amaan.cheval at gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _LIBCPU_AMD64_PAGE_H
+#define _LIBCPU_AMD64_PAGE_H
+
+#ifndef ASM
+
+#define NUM_PAGE_TABLE_ENTRIES 512
+
+extern uint64_t amd64_pml4[NUM_PAGE_TABLE_ENTRIES];
+extern uint64_t amd64_pdpt[NUM_PAGE_TABLE_ENTRIES];
+
+bool paging_1gib_pages_supported(void);
+uint8_t get_maxphysaddr(void);
+uint64_t get_mask_for_bits(uint8_t start, uint8_t end);
+uint64_t create_cr3_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+);
+uint64_t create_pml4_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+);
+uint64_t create_pdpt_entry(
+ uint64_t phys_addr, uint8_t maxphysaddr, uint64_t flags
+);
+
+void paging_init(void);
+
+#define PAGE_FLAGS_PRESENT (1 << 0)
+#define PAGE_FLAGS_WRITABLE (1 << 1)
+#define PAGE_FLAGS_USER_ACCESSIBLE (1 << 2)
+#define PAGE_FLAGS_WRITE_THROUGH (1 << 3)
+#define PAGE_FLAGS_NO_CACHE (1 << 4)
+#define PAGE_FLAGS_ACCESSED (1 << 5)
+#define PAGE_FLAGS_DIRTY (1 << 6)
+#define PAGE_FLAGS_HUGE_PAGE (1 << 7)
+#define PAGE_FLAGS_GLOBAL (1 << 8)
+#define PAGE_FLAGS_NO_EXECUTE (1 << 63)
+
+#define PAGE_FLAGS_DEFAULTS \
+ (PAGE_FLAGS_PRESENT | PAGE_FLAGS_WRITABLE | PAGE_FLAGS_USER_ACCESSIBLE \
+ | PAGE_FLAGS_WRITE_THROUGH | PAGE_FLAGS_NO_CACHE | PAGE_FLAGS_GLOBAL)
+
+#endif /* !ASM */
+#endif
diff --git a/c/src/lib/libbsp/x86_64/amd64/Makefile.am b/c/src/lib/libbsp/x86_64/amd64/Makefile.am
index aa40f6224f..93c4e90fbc 100644
--- a/c/src/lib/libbsp/x86_64/amd64/Makefile.am
+++ b/c/src/lib/libbsp/x86_64/amd64/Makefile.am
@@ -23,6 +23,7 @@ librtemsbsp_a_SOURCES += ../../../../../../bsps/shared/start/bspfatal-default.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/shared/start/bspgetworkarea-default.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/x86_64/amd64/start/bspstart.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/x86_64/amd64/start/start.c
+librtemsbsp_a_SOURCES += ../../../../../../bsps/x86_64/amd64/start/page.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/shared/start/sbrk.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/shared/dev/getentropy/getentropy-cpucounter.c
librtemsbsp_a_SOURCES += ../../../../../../bsps/shared/start/bspreset-empty.c
diff --git a/cpukit/score/cpu/x86_64/include/rtems/score/cpu_asm.h b/cpukit/score/cpu/x86_64/include/rtems/score/cpu_asm.h
index ac43a6366d..5d4b608eb8 100644
--- a/cpukit/score/cpu/x86_64/include/rtems/score/cpu_asm.h
+++ b/cpukit/score/cpu/x86_64/include/rtems/score/cpu_asm.h
@@ -45,6 +45,19 @@ RTEMS_INLINE_ROUTINE void outport_byte(uint16_t port, uint8_t val)
__asm__ volatile ( "outb %0, %1" : : "a" (val), "Nd" (port) );
}
+
+RTEMS_INLINE_ROUTINE void amd64_set_cr3(uint64_t segment)
+{
+ __asm__ volatile ( "movq %0, %%cr3" : "=r" (segment) : "0" (segment) );
+}
+
+RTEMS_INLINE_ROUTINE void cpuid(
+ uint32_t code, uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx
+) {
+ __asm__ volatile ( "cpuid"
+ : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx)
+ : "a" (code) );
+}
#endif /* !ASM */
#endif
--
2.18.0
More information about the devel
mailing list