1 files changed, 308 insertions, 0 deletions
diff --git a/arch/mips/vdso/genvdso.c b/arch/mips/vdso/genvdso.c
new file mode 100644
index 0000000000..09e30eb4be
--- /dev/null
+++ b/arch/mips/vdso/genvdso.c
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2015 Imagination Technologies
+ * Author: Alex Smith <alex.smith@imgtec.com>
+ */
+
+/*
+ * This tool is used to generate the real VDSO images from the raw image. It
+ * first patches up the MIPS ABI flags and GNU attributes sections defined in
+ * elf.S to have the correct name and type. It then generates a C source file
+ * to be compiled into the kernel containing the VDSO image data and a
+ * mips_vdso_image struct for it, including symbol offsets extracted from the
+ * image.
+ *
+ * We need to be passed both a stripped and unstripped VDSO image. The stripped
+ * image is compiled into the kernel, but we must also patch up the unstripped
+ * image's ABI flags sections so that it can be installed and used for
+ * debugging.
+ */
+
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include <byteswap.h>
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/* Define these in case the system elf.h is not new enough to have them. */
+#ifndef SHT_GNU_ATTRIBUTES
+# define SHT_GNU_ATTRIBUTES	0x6ffffff5
+#endif
+#ifndef SHT_MIPS_ABIFLAGS
+# define SHT_MIPS_ABIFLAGS	0x7000002a
+#endif
+
+enum {
+	ABI_O32 = (1 << 0),
+	ABI_N32 = (1 << 1),
+	ABI_N64 = (1 << 2),
+
+	ABI_ALL = ABI_O32 | ABI_N32 | ABI_N64,
+};
+
+/* Symbols the kernel requires offsets for. */
+static struct {
+	const char *name;
+	const char *offset_name;
+	unsigned int abis;
+} vdso_symbols[] = {
+	{ "__vdso_sigreturn", "off_sigreturn", ABI_O32 },
+	{ "__vdso_rt_sigreturn", "off_rt_sigreturn", ABI_ALL },
+	{}
+};
+
+static const char *program_name;
+static const char *vdso_name;
+static unsigned char elf_class;
+static unsigned int elf_abi;
+static bool need_swap;
+static FILE *out_file;
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+# define HOST_ORDER		ELFDATA2LSB
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+# define HOST_ORDER		ELFDATA2MSB
+#endif
+
+#define BUILD_SWAP(bits)						\
+	static uint##bits##_t swap_uint##bits(uint##bits##_t val)	\
+	{								\
+		return need_swap ? bswap_##bits(val) : val;		\
+	}
+
+BUILD_SWAP(16)
+BUILD_SWAP(32)
+BUILD_SWAP(64)
+
+#define __FUNC(name, bits) name##bits
+#define _FUNC(name, bits) __FUNC(name, bits)
+#define FUNC(name) _FUNC(name, ELF_BITS)
+
+#define __ELF(x, bits) Elf##bits##_##x
+#define _ELF(x, bits) __ELF(x, bits)
+#define ELF(x) _ELF(x, ELF_BITS)
+
+/*
+ * Include genvdso.h twice with ELF_BITS defined differently to get functions
+ * for both ELF32 and ELF64.
+ */
+
+#define ELF_BITS 64
+#include "genvdso.h"
+#undef ELF_BITS
+
+#define ELF_BITS 32
+#include "genvdso.h"
+#undef ELF_BITS
+
+static void *map_vdso(const char *path, size_t *_size)
+{
+	int fd;
+	struct stat stat;
+	void *addr;
+	const Elf32_Ehdr *ehdr;
+
+	fd = open(path, O_RDWR);
+	if (fd < 0) {
+		fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
+			path, strerror(errno));
+		return NULL;
+	}
+
+	if (fstat(fd, &stat) != 0) {
+		fprintf(stderr, "%s: Failed to stat '%s': %s\n", program_name,
+			path, strerror(errno));
+		close(fd);
+		return NULL;
+	}
+
+	addr = mmap(NULL, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd,
+		    0);
+	if (addr == MAP_FAILED) {
+		fprintf(stderr, "%s: Failed to map '%s': %s\n", program_name,
+			path, strerror(errno));
+		close(fd);
+		return NULL;
+	}
+
+	/* ELF32/64 header formats are the same for the bits we're checking. */
+	ehdr = addr;
+
+	if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) != 0) {
+		fprintf(stderr, "%s: '%s' is not an ELF file\n", program_name,
+			path);
+		close(fd);
+		return NULL;
+	}
+
+	elf_class = ehdr->e_ident[EI_CLASS];
+	switch (elf_class) {
+	case ELFCLASS32:
+	case ELFCLASS64:
+		break;
+	default:
+		fprintf(stderr, "%s: '%s' has invalid ELF class\n",
+			program_name, path);
+		close(fd);
+		return NULL;
+	}
+
+	switch (ehdr->e_ident[EI_DATA]) {
+	case ELFDATA2LSB:
+	case ELFDATA2MSB:
+		need_swap = ehdr->e_ident[EI_DATA] != HOST_ORDER;
+		break;
+	default:
+		fprintf(stderr, "%s: '%s' has invalid ELF data order\n",
+			program_name, path);
+		close(fd);
+		return NULL;
+	}
+
+	if (swap_uint16(ehdr->e_machine) != EM_MIPS) {
+		fprintf(stderr,
+			"%s: '%s' has invalid ELF machine (expected EM_MIPS)\n",
+			program_name, path);
+		close(fd);
+		return NULL;
+	} else if (swap_uint16(ehdr->e_type) != ET_DYN) {
+		fprintf(stderr,
+			"%s: '%s' has invalid ELF type (expected ET_DYN)\n",
+			program_name, path);
+		close(fd);
+		return NULL;
+	}
+
+	*_size = stat.st_size;
+	close(fd);
+	return addr;
+}
+
+static bool patch_vdso(const char *path, void *vdso)
+{
+	if (elf_class == ELFCLASS64)
+		return patch_vdso64(path, vdso);
+	else
+		return patch_vdso32(path, vdso);
+}
+
+static bool get_symbols(const char *path, void *vdso)
+{
+	if (elf_class == ELFCLASS64)
+		return get_symbols64(path, vdso);
+	else
+		return get_symbols32(path, vdso);
+}
+
+int main(int argc, char **argv)
+{
+	const char *dbg_vdso_path, *vdso_path, *out_path;
+	void *dbg_vdso, *vdso;
+	size_t dbg_vdso_size, vdso_size, i;
+
+	program_name = argv[0];
+
+	if (argc < 4 || argc > 5) {
+		fprintf(stderr,
+			"Usage: %s <debug VDSO> <stripped VDSO> <output file> [<name>]\n",
+			program_name);
+		return EXIT_FAILURE;
+	}
+
+	dbg_vdso_path = argv[1];
+	vdso_path = argv[2];
+	out_path = argv[3];
+	vdso_name = (argc > 4) ? argv[4] : "";
+
+	dbg_vdso = map_vdso(dbg_vdso_path, &dbg_vdso_size);
+	if (!dbg_vdso)
+		return EXIT_FAILURE;
+
+	vdso = map_vdso(vdso_path, &vdso_size);
+	if (!vdso)
+		return EXIT_FAILURE;
+
+	/* Patch both the VDSOs' ABI flags sections. */
+	if (!patch_vdso(dbg_vdso_path, dbg_vdso))
+		return EXIT_FAILURE;
+	if (!patch_vdso(vdso_path, vdso))
+		return EXIT_FAILURE;
+
+	if (msync(dbg_vdso, dbg_vdso_size, MS_SYNC) != 0) {
+		fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
+			dbg_vdso_path, strerror(errno));
+		return EXIT_FAILURE;
+	} else if (msync(vdso, vdso_size, MS_SYNC) != 0) {
+		fprintf(stderr, "%s: Failed to sync '%s': %s\n", program_name,
+			vdso_path, strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	out_file = fopen(out_path, "w");
+	if (!out_file) {
+		fprintf(stderr, "%s: Failed to open '%s': %s\n", program_name,
+			out_path, strerror(errno));
+		return EXIT_FAILURE;
+	}
+
+	fprintf(out_file, "/* Automatically generated - do not edit */\n");
+	fprintf(out_file, "#include <linux/linkage.h>\n");
+	fprintf(out_file, "#include <linux/mm.h>\n");
+	fprintf(out_file, "#include <asm/vdso.h>\n");
+	fprintf(out_file, "static int vdso_mremap(\n");
+	fprintf(out_file, "	const struct vm_special_mapping *sm,\n");
+	fprintf(out_file, "	struct vm_area_struct *new_vma)\n");
+	fprintf(out_file, "{\n");
+	fprintf(out_file, "	current->mm->context.vdso =\n");
+	fprintf(out_file, "	(void *)(new_vma->vm_start);\n");
+	fprintf(out_file, "	return 0;\n");
+	fprintf(out_file, "}\n");
+
+	/* Write out the stripped VDSO data. */
+	fprintf(out_file,
+		"static unsigned char vdso_data[PAGE_ALIGN(%zu)] __page_aligned_data = {\n\t",
+		vdso_size);
+	for (i = 0; i < vdso_size; i++) {
+		if (!(i % 10))
+			fprintf(out_file, "\n\t");
+		fprintf(out_file, "0x%02x, ", ((unsigned char *)vdso)[i]);
+	}
+	fprintf(out_file, "\n};\n");
+
+	/* Preallocate a page array. */
+	fprintf(out_file,
+		"static struct page *vdso_pages[PAGE_ALIGN(%zu) / PAGE_SIZE];\n",
+		vdso_size);
+
+	fprintf(out_file, "struct mips_vdso_image vdso_image%s%s = {\n",
+		(vdso_name[0]) ? "_" : "", vdso_name);
+	fprintf(out_file, "\t.data = vdso_data,\n");
+	fprintf(out_file, "\t.size = PAGE_ALIGN(%zu),\n", vdso_size);
+	fprintf(out_file, "\t.mapping = {\n");
+	fprintf(out_file, "\t\t.name = \"[vdso]\",\n");
+	fprintf(out_file, "\t\t.pages = vdso_pages,\n");
+	fprintf(out_file, "\t\t.mremap = vdso_mremap,\n");
+	fprintf(out_file, "\t},\n");
+
+	/* Calculate and write symbol offsets to <output file> */
+	if (!get_symbols(dbg_vdso_path, dbg_vdso)) {
+		unlink(out_path);
+		fclose(out_file);
+		return EXIT_FAILURE;
+	}
+
+	fprintf(out_file, "};\n");
+	fclose(out_file);
+
+	return EXIT_SUCCESS;
+}