x86, vdso: Move the vvar area before the vdso text (e6577a7c) · Commits · 戴 / test

arch/x86/include/asm/vdso.h

+9 −9

Original line number	Diff line number	Diff line
		@@ -18,15 +18,15 @@ struct vdso_image {

		unsigned long alt, alt_len;

		unsigned long sym_end_mapping; /* Total size of the mapping */

		unsigned long sym_vvar_page;
		unsigned long sym_hpet_page;
		unsigned long sym_VDSO32_NOTE_MASK;
		unsigned long sym___kernel_sigreturn;
		unsigned long sym___kernel_rt_sigreturn;
		unsigned long sym___kernel_vsyscall;
		unsigned long sym_VDSO32_SYSENTER_RETURN;
		long sym_vvar_start; /* Negative offset to the vvar area */

		long sym_vvar_page;
		long sym_hpet_page;
		long sym_VDSO32_NOTE_MASK;
		long sym___kernel_sigreturn;
		long sym___kernel_rt_sigreturn;
		long sym___kernel_vsyscall;
		long sym_VDSO32_SYSENTER_RETURN;
		};

		#ifdef CONFIG_X86_64

arch/x86/vdso/vdso-layout.lds.S

+19 −25

Original line number	Diff line number	Diff line
		@@ -18,6 +18,25 @@

		SECTIONS
		{
		/*
		* User/kernel shared data is before the vDSO. This may be a little
		* uglier than putting it after the vDSO, but it avoids issues with
		* non-allocatable things that dangle past the end of the PT_LOAD
		* segment.
		*/

		vvar_start = . - 2 * PAGE_SIZE;
		vvar_page = vvar_start;

		/* Place all vvars at the offsets in asm/vvar.h. */
		#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
		#define __VVAR_KERNEL_LDS
		#include <asm/vvar.h>
		#undef __VVAR_KERNEL_LDS
		#undef EMIT_VVAR

		hpet_page = vvar_start + PAGE_SIZE;

		. = SIZEOF_HEADERS;

		.hash : { *(.hash) } :text
		@@ -74,31 +93,6 @@ SECTIONS
		.altinstructions : { *(.altinstructions) } :text
		.altinstr_replacement : { *(.altinstr_replacement) } :text

		/*
		* The remainder of the vDSO consists of special pages that are
		* shared between the kernel and userspace. It needs to be at the
		* end so that it doesn't overlap the mapping of the actual
		* vDSO image.
		*/

		. = ALIGN(PAGE_SIZE);
		vvar_page = .;

		/* Place all vvars at the offsets in asm/vvar.h. */
		#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
		#define __VVAR_KERNEL_LDS
		#include <asm/vvar.h>
		#undef __VVAR_KERNEL_LDS
		#undef EMIT_VVAR

		. = vvar_page + PAGE_SIZE;

		hpet_page = .;
		. = . + PAGE_SIZE;

		. = ALIGN(PAGE_SIZE);
		end_mapping = .;

		/DISCARD/ : {
		*(.discard)
		(.discard.)

arch/x86/vdso/vdso2c.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -20,9 +20,9 @@ const char *outfilename;

		/* Symbols that we need in vdso2c. */
		enum {
		sym_vvar_start,
		sym_vvar_page,
		sym_hpet_page,
		sym_end_mapping,
		sym_VDSO_FAKE_SECTION_TABLE_START,
		sym_VDSO_FAKE_SECTION_TABLE_END,
		};
		@@ -38,9 +38,9 @@ struct vdso_sym {
		};

		struct vdso_sym required_syms[] = {
		[sym_vvar_start] = {"vvar_start", true},
		[sym_vvar_page] = {"vvar_page", true},
		[sym_hpet_page] = {"hpet_page", true},
		[sym_end_mapping] = {"end_mapping", true},
		[sym_VDSO_FAKE_SECTION_TABLE_START] = {
		"VDSO_FAKE_SECTION_TABLE_START", false
		},
		@@ -96,9 +96,11 @@ extern void bad_put_le(void);

		#define NSYMS (sizeof(required_syms) / sizeof(required_syms[0]))

		#define BITSFUNC3(name, bits) name##bits
		#define BITSFUNC2(name, bits) BITSFUNC3(name, bits)
		#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS)
		#define BITSFUNC3(name, bits, suffix) name##bits##suffix
		#define BITSFUNC2(name, bits, suffix) BITSFUNC3(name, bits, suffix)
		#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS, )

		#define INT_BITS BITSFUNC2(int, ELF_BITS, _t)

		#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x
		#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)

arch/x86/vdso/vdso2c.h

+16 −9

Original line number	Diff line number	Diff line
		@@ -132,7 +132,7 @@ static void BITSFUNC(go)(void *addr, size_t len,
		*alt_sec = NULL;
		ELF(Dyn) dyn = 0, dyn_end = 0;
		const char *secstrings;
		uint64_t syms[NSYMS] = {};
		INT_BITS syms[NSYMS] = {};

		struct BITSFUNC(fake_sections) fake_sections = {};

		@@ -209,6 +209,13 @@ static void BITSFUNC(go)(void *addr, size_t len,
		fail("duplicate symbol %s\n",
		required_syms[k].name);
		}

		/*
		* Careful: we use negative addresses, but
		* st_value is unsigned, so we rely
		* on syms[k] being a signed type of the
		* correct width.
		*/
		syms[k] = GET_LE(&sym->st_value);
		}
		}
		@@ -263,15 +270,15 @@ static void BITSFUNC(go)(void *addr, size_t len,
		if (syms[i] % 4096)
		fail("%s must be a multiple of 4096\n",
		required_syms[i].name);
		if (syms[i] < data_size)
		fail("%s must be after the text mapping\n",
		if (syms[sym_vvar_start] > syms[i] + 4096)
		fail("%s underruns begin_vvar\n",
		required_syms[i].name);
		if (syms[sym_end_mapping] < syms[i] + 4096)
		fail("%s overruns end_mapping\n",
		if (syms[i] + 4096 > 0)
		fail("%s is on the wrong side of the vdso text\n",
		required_syms[i].name);
		}
		if (syms[sym_end_mapping] % 4096)
		fail("end_mapping must be a multiple of 4096\n");
		if (syms[sym_vvar_start] % 4096)
		fail("vvar_begin must be a multiple of 4096\n");

		if (!name) {
		fwrite(addr, load_size, 1, outfile);
		@@ -311,8 +318,8 @@ static void BITSFUNC(go)(void *addr, size_t len,
		}
		for (i = 0; i < NSYMS; i++) {
		if (required_syms[i].export && syms[i])
		fprintf(outfile, "\t.sym_%s = 0x%" PRIx64 ",\n",
		required_syms[i].name, syms[i]);
		fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n",
		required_syms[i].name, (int64_t)syms[i]);
		}
		fprintf(outfile, "};\n");
		}

arch/x86/vdso/vma.c

+11 −9

Original line number	Diff line number	Diff line
		@@ -93,7 +93,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
		{
		struct mm_struct *mm = current->mm;
		struct vm_area_struct *vma;
		unsigned long addr;
		unsigned long addr, text_start;
		int ret = 0;
		static struct page *no_pages[] = {NULL};
		static struct vm_special_mapping vvar_mapping = {
		@@ -103,26 +103,28 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)

		if (calculate_addr) {
		addr = vdso_addr(current->mm->start_stack,
		image->sym_end_mapping);
		image->size - image->sym_vvar_start);
		} else {
		addr = 0;
		}

		down_write(&mm->mmap_sem);

		addr = get_unmapped_area(NULL, addr, image->sym_end_mapping, 0, 0);
		addr = get_unmapped_area(NULL, addr,
		image->size - image->sym_vvar_start, 0, 0);
		if (IS_ERR_VALUE(addr)) {
		ret = addr;
		goto up_fail;
		}

		current->mm->context.vdso = (void __user *)addr;
		text_start = addr - image->sym_vvar_start;
		current->mm->context.vdso = (void __user *)text_start;

		/*
		* MAYWRITE to allow gdb to COW and set breakpoints
		*/
		vma = _install_special_mapping(mm,
		addr,
		text_start,
		image->size,
		VM_READ\|VM_EXEC\|
		VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC,
		@@ -134,8 +136,8 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
		}

		vma = _install_special_mapping(mm,
		addr + image->size,
		image->sym_end_mapping - image->size,
		addr,
		-image->sym_vvar_start,
		VM_READ,
		&vvar_mapping);

		@@ -146,7 +148,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)

		if (image->sym_vvar_page)
		ret = remap_pfn_range(vma,
		addr + image->sym_vvar_page,
		text_start + image->sym_vvar_page,
		__pa_symbol(&__vvar_page) >> PAGE_SHIFT,
		PAGE_SIZE,
		PAGE_READONLY);
		@@ -157,7 +159,7 @@ static int map_vdso(const struct vdso_image *image, bool calculate_addr)
		#ifdef CONFIG_HPET_TIMER
		if (hpet_address && image->sym_hpet_page) {
		ret = io_remap_pfn_range(vma,
		addr + image->sym_hpet_page,
		text_start + image->sym_hpet_page,
		hpet_address >> PAGE_SHIFT,
		PAGE_SIZE,
		pgprot_noncached(PAGE_READONLY));

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