x86, relocs: Move ELF relocation handling to C (a0215061) · Commits · 戴 / test

arch/x86/Kconfig

+6 −2

Original line number	Diff line number	Diff line
		@@ -1716,9 +1716,10 @@ config X86_NEED_RELOCS
		depends on X86_32 && RELOCATABLE

		config PHYSICAL_ALIGN
		hex "Alignment value to which kernel should be aligned" if X86_32
		hex "Alignment value to which kernel should be aligned"
		default "0x1000000"
		range 0x2000 0x1000000
		range 0x2000 0x1000000 if X86_32
		range 0x200000 0x1000000 if X86_64
		---help---
		This value puts the alignment restrictions on physical address
		where kernel is loaded and run from. Kernel is compiled for an
		@@ -1736,6 +1737,9 @@ config PHYSICAL_ALIGN
		end result is that kernel runs from a physical address meeting
		above alignment restrictions.

		On 32-bit this value must be a multiple of 0x2000. On 64-bit
		this value must be a multiple of 0x200000.

		Don't change this unless you know what you are doing.

		config HOTPLUG_CPU

arch/x86/Makefile

+4 −4

Original line number	Diff line number	Diff line
		@@ -16,6 +16,10 @@ endif
		# e.g.: obj-y += foo_$(BITS).o
		export BITS

		ifdef CONFIG_X86_NEED_RELOCS
		LDFLAGS_vmlinux := --emit-relocs
		endif

		ifeq ($(CONFIG_X86_32),y)
		BITS := 32
		UTS_MACHINE := i386
		@@ -25,10 +29,6 @@ ifeq ($(CONFIG_X86_32),y)
		KBUILD_AFLAGS += $(biarch)
		KBUILD_CFLAGS += $(biarch)

		ifdef CONFIG_RELOCATABLE
		LDFLAGS_vmlinux := --emit-relocs
		endif

		KBUILD_CFLAGS += -msoft-float -mregparm=3 -freg-struct-return

		# Never want PIC in a 32-bit kernel, prevent breakage with GCC built

arch/x86/boot/compressed/head_32.S

+3 −28

Original line number	Diff line number	Diff line
		@@ -181,8 +181,9 @@ relocated:
		/*
		* Do the decompression, and jump to the new kernel..
		*/
		leal z_extract_offset_negative(%ebx), %ebp
		/* push arguments for decompress_kernel: */
		pushl $z_output_len /* decompressed length */
		leal z_extract_offset_negative(%ebx), %ebp
		pushl %ebp /* output address */
		pushl $z_input_len /* input_len */
		leal input_data(%ebx), %eax
		@@ -191,33 +192,7 @@ relocated:
		pushl %eax /* heap area */
		pushl %esi /* real mode pointer */
		call decompress_kernel
		addl $20, %esp

		#if CONFIG_RELOCATABLE
		/*
		* Find the address of the relocations.
		*/
		leal z_output_len(%ebp), %edi

		/*
		* Calculate the delta between where vmlinux was compiled to run
		* and where it was actually loaded.
		*/
		movl %ebp, %ebx
		subl $LOAD_PHYSICAL_ADDR, %ebx
		jz 2f /* Nothing to be done if loaded at compiled addr. */
		/*
		* Process relocations.
		*/

		1: subl $4, %edi
		movl (%edi), %ecx
		testl %ecx, %ecx
		jz 2f
		addl %ebx, -__PAGE_OFFSET(%ebx, %ecx)
		jmp 1b
		2:
		#endif
		addl $24, %esp

		/*
		* Jump to the decompressed kernel.

arch/x86/boot/compressed/head_64.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -338,6 +338,7 @@ relocated:
		leaq input_data(%rip), %rdx /* input_data */
		movl $z_input_len, %ecx /* input_len */
		movq %rbp, %r8 /* output target address */
		movq $z_output_len, %r9 /* decompressed length */
		call decompress_kernel
		popq %rsi

arch/x86/boot/compressed/misc.c

+76 −1

Original line number	Diff line number	Diff line
		@@ -271,6 +271,79 @@ static void error(char *x)
		asm("hlt");
		}

		#if CONFIG_X86_NEED_RELOCS
		static void handle_relocations(void *output, unsigned long output_len)
		{
		int *reloc;
		unsigned long delta, map, ptr;
		unsigned long min_addr = (unsigned long)output;
		unsigned long max_addr = min_addr + output_len;

		/*
		* Calculate the delta between where vmlinux was linked to load
		* and where it was actually loaded.
		*/
		delta = min_addr - LOAD_PHYSICAL_ADDR;
		if (!delta) {
		debug_putstr("No relocation needed... ");
		return;
		}
		debug_putstr("Performing relocations... ");

		/*
		* The kernel contains a table of relocation addresses. Those
		* addresses have the final load address of the kernel in virtual
		* memory. We are currently working in the self map. So we need to
		* create an adjustment for kernel memory addresses to the self map.
		* This will involve subtracting out the base address of the kernel.
		*/
		map = delta - __START_KERNEL_map;

		/*
		* Process relocations: 32 bit relocations first then 64 bit after.
		* Two sets of binary relocations are added to the end of the kernel
		* before compression. Each relocation table entry is the kernel
		* address of the location which needs to be updated stored as a
		* 32-bit value which is sign extended to 64 bits.
		*
		* Format is:
		*
		* kernel bits...
		* 0 - zero terminator for 64 bit relocations
		* 64 bit relocation repeated
		* 0 - zero terminator for 32 bit relocations
		* 32 bit relocation repeated
		*
		* So we work backwards from the end of the decompressed image.
		*/
		for (reloc = output + output_len - sizeof(reloc); reloc; reloc--) {
		int extended = *reloc;
		extended += map;

		ptr = (unsigned long)extended;
		if (ptr < min_addr \|\| ptr > max_addr)
		error("32-bit relocation outside of kernel!\n");

		(uint32_t )ptr += delta;
		}
		#ifdef CONFIG_X86_64
		for (reloc--; *reloc; reloc--) {
		long extended = *reloc;
		extended += map;

		ptr = (unsigned long)extended;
		if (ptr < min_addr \|\| ptr > max_addr)
		error("64-bit relocation outside of kernel!\n");

		(uint64_t )ptr += delta;
		}
		#endif
		}
		#else
		static inline void handle_relocations(void *output, unsigned long output_len)
		{ }
		#endif

		static void parse_elf(void *output)
		{
		#ifdef CONFIG_X86_64
		@@ -325,7 +398,8 @@ static void parse_elf(void *output)
		asmlinkage void decompress_kernel(void *rmode, memptr heap,
		unsigned char *input_data,
		unsigned long input_len,
		unsigned char *output)
		unsigned char *output,
		unsigned long output_len)
		{
		real_mode = rmode;

		@@ -365,6 +439,7 @@ asmlinkage void decompress_kernel(void *rmode, memptr heap,
		debug_putstr("\nDecompressing Linux... ");
		decompress(input_data, input_len, NULL, NULL, output, NULL, error);
		parse_elf(output);
		handle_relocations(output, output_len);
		debug_putstr("done.\nBooting the kernel.\n");
		return;
		}

Admin message