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Commit 63004afa authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull straggler x86 fixes from Peter Anvin:
 "Three groups of patches:

  - EFI boot stub documentation and the ability to print error messages;
  - Removal for PTRACE_ARCH_PRCTL for x32 (obsolete interface which
    should never have been ported, and the port is broken and
    potentially dangerous.)
  - ftrace stack corruption fixes.  I'm not super-happy about the
    technical implementation, but it is probably the least invasive in
    the short term.  In the future I would like a single method for
    nesting the debug stack, however."

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86, x32, ptrace: Remove PTRACE_ARCH_PRCTL for x32
  x86, efi: Add EFI boot stub documentation
  x86, efi; Add EFI boot stub console support
  x86, efi: Only close open files in error path
  ftrace/x86: Do not change stacks in DEBUG when calling lockdep
  x86: Allow nesting of the debug stack IDT setting
  x86: Reset the debug_stack update counter
  ftrace: Use breakpoint method to update ftrace caller
  ftrace: Synchronize variable setting with breakpoints
parents f309532b 40b46a7d

Documentation/x86/efi-stub.txt

0 → 100644
+65 −0
Original line number Diff line number Diff line 
			  The EFI Boot Stub

		     ---------------------------



On the x86 platform, a bzImage can masquerade as a PE/COFF image,

thereby convincing EFI firmware loaders to load it as an EFI

executable. The code that modifies the bzImage header, along with the

EFI-specific entry point that the firmware loader jumps to are

collectively known as the "EFI boot stub", and live in

arch/x86/boot/header.S and arch/x86/boot/compressed/eboot.c,

respectively.



By using the EFI boot stub it's possible to boot a Linux kernel

without the use of a conventional EFI boot loader, such as grub or

elilo. Since the EFI boot stub performs the jobs of a boot loader, in

a certain sense it *IS* the boot loader.



The EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.





**** How to install bzImage.efi



The bzImage located in arch/x86/boot/bzImage must be copied to the EFI

System Partiion (ESP) and renamed with the extension ".efi". Without

the extension the EFI firmware loader will refuse to execute it. It's

not possible to execute bzImage.efi from the usual Linux file systems

because EFI firmware doesn't have support for them.





**** Passing kernel parameters from the EFI shell



Arguments to the kernel can be passed after bzImage.efi, e.g.



	fs0:> bzImage.efi console=ttyS0 root=/dev/sda4





**** The "initrd=" option



Like most boot loaders, the EFI stub allows the user to specify

multiple initrd files using the "initrd=" option. This is the only EFI

stub-specific command line parameter, everything else is passed to the

kernel when it boots.



The path to the initrd file must be an absolute path from the

beginning of the ESP, relative path names do not work. Also, the path

is an EFI-style path and directory elements must be separated with

backslashes (\). For example, given the following directory layout,



fs0:>

	Kernels\

			bzImage.efi

			initrd-large.img



	Ramdisks\

			initrd-small.img

			initrd-medium.img



to boot with the initrd-large.img file if the current working

directory is fs0:\Kernels, the following command must be used,



	fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img



Notice how bzImage.efi can be specified with a relative path. That's

because the image we're executing is interpreted by the EFI shell,

which understands relative paths, whereas the rest of the command line

is passed to bzImage.efi.

arch/x86/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -1506,6 +1506,8 @@ config EFI_STUB 
          This kernel feature allows a bzImage to be loaded directly

	  by EFI firmware without the use of a bootloader.



	  See Documentation/x86/efi-stub.txt for more information.



config SECCOMP

	def_bool y

	prompt "Enable seccomp to safely compute untrusted bytecode"

arch/x86/boot/compressed/eboot.c

+70 −17
Original line number Diff line number Diff line
@@ -16,6 +16,26 @@ 


static efi_system_table_t *sys_table;



static void efi_printk(char *str)

{

	char *s8;



	for (s8 = str; *s8; s8++) {

		struct efi_simple_text_output_protocol *out;

		efi_char16_t ch[2] = { 0 };



		ch[0] = *s8;

		out = (struct efi_simple_text_output_protocol *)sys_table->con_out;



		if (*s8 == '\n') {

			efi_char16_t nl[2] = { '\r', 0 };

			efi_call_phys2(out->output_string, out, nl);

		}



		efi_call_phys2(out->output_string, out, ch);

	}

}



static efi_status_t __get_map(efi_memory_desc_t **map, unsigned long *map_size,

			      unsigned long *desc_size)

{
@@ -531,8 +551,10 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image, 
				EFI_LOADER_DATA,

				nr_initrds * sizeof(*initrds),

				&initrds);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to alloc mem for initrds\n");

		goto fail;

	}



	str = (char *)(unsigned long)hdr->cmd_line_ptr;

	for (i = 0; i < nr_initrds; i++) {
@@ -575,32 +597,42 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image, 


			status = efi_call_phys3(boottime->handle_protocol,

					image->device_handle, &fs_proto, &io);

			if (status != EFI_SUCCESS)

			if (status != EFI_SUCCESS) {

				efi_printk("Failed to handle fs_proto\n");

				goto free_initrds;

			}



			status = efi_call_phys2(io->open_volume, io, &fh);

			if (status != EFI_SUCCESS)

			if (status != EFI_SUCCESS) {

				efi_printk("Failed to open volume\n");

				goto free_initrds;

			}

		}



		status = efi_call_phys5(fh->open, fh, &h, filename_16,

					EFI_FILE_MODE_READ, (u64)0);

		if (status != EFI_SUCCESS)

		if (status != EFI_SUCCESS) {

			efi_printk("Failed to open initrd file\n");

			goto close_handles;

		}



		initrd->handle = h;



		info_sz = 0;

		status = efi_call_phys4(h->get_info, h, &info_guid,

					&info_sz, NULL);

		if (status != EFI_BUFFER_TOO_SMALL)

		if (status != EFI_BUFFER_TOO_SMALL) {

			efi_printk("Failed to get initrd info size\n");

			goto close_handles;

		}



grow:

		status = efi_call_phys3(sys_table->boottime->allocate_pool,

					EFI_LOADER_DATA, info_sz, &info);

		if (status != EFI_SUCCESS)

		if (status != EFI_SUCCESS) {

			efi_printk("Failed to alloc mem for initrd info\n");

			goto close_handles;

		}



		status = efi_call_phys4(h->get_info, h, &info_guid,

					&info_sz, info);
@@ -612,8 +644,10 @@ grow: 
		file_sz = info->file_size;

		efi_call_phys1(sys_table->boottime->free_pool, info);



		if (status != EFI_SUCCESS)

		if (status != EFI_SUCCESS) {

			efi_printk("Failed to get initrd info\n");

			goto close_handles;

		}



		initrd->size = file_sz;

		initrd_total += file_sz;
@@ -629,11 +663,14 @@ grow: 
		 */

		status = high_alloc(initrd_total, 0x1000,

				   &initrd_addr, hdr->initrd_addr_max);

		if (status != EFI_SUCCESS)

		if (status != EFI_SUCCESS) {

			efi_printk("Failed to alloc highmem for initrds\n");

			goto close_handles;

		}



		/* We've run out of free low memory. */

		if (initrd_addr > hdr->initrd_addr_max) {

			efi_printk("We've run out of free low memory\n");

			status = EFI_INVALID_PARAMETER;

			goto free_initrd_total;

		}
@@ -652,8 +689,10 @@ grow: 
				status = efi_call_phys3(fh->read,

							initrds[j].handle,

							&chunksize, addr);

				if (status != EFI_SUCCESS)

				if (status != EFI_SUCCESS) {

					efi_printk("Failed to read initrd\n");

					goto free_initrd_total;

				}

				addr += chunksize;

				size -= chunksize;

			}
@@ -674,7 +713,7 @@ free_initrd_total: 
	low_free(initrd_total, initrd_addr);



close_handles:

	for (k = j; k < nr_initrds; k++)

	for (k = j; k < i; k++)

		efi_call_phys1(fh->close, initrds[k].handle);

free_initrds:

	efi_call_phys1(sys_table->boottime->free_pool, initrds);
@@ -732,8 +771,10 @@ static efi_status_t make_boot_params(struct boot_params *boot_params, 
			options_size++;	/* NUL termination */



			status = low_alloc(options_size, 1, &cmdline);

			if (status != EFI_SUCCESS)

			if (status != EFI_SUCCESS) {

				efi_printk("Failed to alloc mem for cmdline\n");

				goto fail;

			}



			s1 = (u8 *)(unsigned long)cmdline;

			s2 = (u16 *)options;
@@ -895,12 +936,16 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table) 


	status = efi_call_phys3(sys_table->boottime->handle_protocol,

				handle, &proto, (void *)&image);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n");

		goto fail;

	}



	status = low_alloc(0x4000, 1, (unsigned long *)&boot_params);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to alloc lowmem for boot params\n");

		goto fail;

	}



	memset(boot_params, 0x0, 0x4000);
@@ -933,9 +978,11 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table) 
	if (status != EFI_SUCCESS) {

		status = low_alloc(hdr->init_size, hdr->kernel_alignment,

				   &start);

		if (status != EFI_SUCCESS)

		if (status != EFI_SUCCESS) {

			efi_printk("Failed to alloc mem for kernel\n");

			goto fail;

		}

	}



	hdr->code32_start = (__u32)start;

	hdr->pref_address = (__u64)(unsigned long)image->image_base;
@@ -945,19 +992,25 @@ struct boot_params *efi_main(void *handle, efi_system_table_t *_table) 
	status = efi_call_phys3(sys_table->boottime->allocate_pool,

				EFI_LOADER_DATA, sizeof(*gdt),

				(void **)&gdt);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to alloc mem for gdt structure\n");

		goto fail;

	}



	gdt->size = 0x800;

	status = low_alloc(gdt->size, 8, (unsigned long *)&gdt->address);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to alloc mem for gdt\n");

		goto fail;

	}



	status = efi_call_phys3(sys_table->boottime->allocate_pool,

				EFI_LOADER_DATA, sizeof(*idt),

				(void **)&idt);

	if (status != EFI_SUCCESS)

	if (status != EFI_SUCCESS) {

		efi_printk("Failed to alloc mem for idt structure\n");

		goto fail;

	}



	idt->size = 0;

	idt->address = 0;

arch/x86/boot/compressed/eboot.h

+6 −0
Original line number Diff line number Diff line
@@ -58,4 +58,10 @@ struct efi_uga_draw_protocol { 
	void *blt;

};



struct efi_simple_text_output_protocol {

	void *reset;

	void *output_string;

	void *test_string;

};



#endif /* BOOT_COMPRESSED_EBOOT_H */

arch/x86/include/asm/ftrace.h

+1 −1
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 


#ifndef __ASSEMBLY__

extern void mcount(void);

extern int modifying_ftrace_code;

extern atomic_t modifying_ftrace_code;



static inline unsigned long ftrace_call_adjust(unsigned long addr)

{