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2020-05-20efi/libstub: Add UTF-8 decoding to efi_putsArvind Sankar1-5/+62
In order to be able to use the UTF-16 support added to vsprintf in the previous commit, enhance efi_puts to decode UTF-8 into UTF-16. Invalid UTF-8 encodings are passed through unchanged. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-22-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-20efi/printf: Add support for wchar_t (UTF-16)Arvind Sankar1-5/+106
Support %lc and %ls to output UTF-16 strings (converted to UTF-8). Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-21-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-20efi/gop: Add an option to list out the available GOP modesArvind Sankar3-1/+133
Add video=efifb:list option to list the modes that are available. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-20-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-20efi/libstub: Add definitions for console input and eventsArvind Sankar1-5/+72
Add the required typedefs etc for using con_in's simple text input protocol, and for using the boottime event services. Also add the prototype for the "stall" boot service. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-19-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-20efi/libstub: Implement printk-style loggingArvind Sankar2-8/+35
Use the efi_printk function in efi_info/efi_err, and add efi_debug. This allows formatted output at different log levels. Add the notion of a loglevel instead of just quiet/not-quiet, and parse the efi=debug kernel parameter in addition to quiet. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200520170223.GA3333632@rani.riverdale.lan/ Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Turn vsprintf into vsnprintfArvind Sankar2-18/+30
Implement vsnprintf instead of vsprintf to avoid the possibility of a buffer overflow. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-17-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Abort on invalid formatArvind Sankar1-6/+8
If we get an invalid conversion specifier, bail out instead of trying to fix it up. The format string likely has a typo or assumed we support something that we don't, in either case the remaining arguments won't match up with the remaining format string. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-16-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Refactor code to consolidate padding and outputArvind Sankar1-126/+148
Consolidate the actual output of the formatted text into one place. Fix a couple of edge cases: 1. If 0 is printed with a precision of 0, the printf specification says that nothing should be output, with one exception (2b). 2. The specification for octal alternate format (%#o) adds the leading zero not as a prefix as the 0x for hexadecimal is, but by increasing the precision if necessary to add the zero. This means that a. %#.2o turns 8 into "010", but 1 into "01" rather than "001". b. %#.o prints 0 as "0" rather than "", unlike the situation for decimal, hexadecimal and regular octal format, which all output an empty string. Reduce the space allocated for printing a number to the maximum actually required (22 bytes for a 64-bit number in octal), instead of the 66 bytes previously allocated. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-15-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Handle null string inputArvind Sankar1-0/+5
Print "(null)" for 's' if the input is a NULL pointer. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-14-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Factor out integer argument retrievalArvind Sankar1-33/+33
Factor out the code to get the correct type of numeric argument into a helper function. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-13-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Factor out width/precision parsingArvind Sankar1-21/+40
Factor out the width/precision parsing into a helper function. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-12-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Merge 'p' with the integer formatsArvind Sankar1-14/+8
Treat 'p' as a hexadecimal integer with precision equal to the number of digits in void *. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-11-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Fix minor bug in precision handlingArvind Sankar1-2/+4
A negative precision should be ignored completely, and the presence of a valid precision should turn off the 0 flag. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-10-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Factor out flags parsing and handle '%' earlierArvind Sankar1-25/+31
Move flags parsing code out into a helper function. The '%%' case can be handled up front: it is not allowed to have flags, width etc. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-9-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Add 64-bit and 8-bit integer supportArvind Sankar1-27/+143
Support 'll' qualifier for long long by copying the decimal printing code from lib/vsprintf.c. For simplicity, the 32-bit code is used on 64-bit architectures as well. Support 'hh' qualifier for signed/unsigned char type integers. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-8-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/printf: Drop %n format and L qualifierArvind Sankar1-12/+2
%n is unused and deprecated. The L qualifer is parsed but not actually implemented. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-7-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/libstub: Optimize for size instead of speedArvind Sankar1-2/+2
Reclaim the bloat from the addition of printf by optimizing the stub for size. With gcc 9, the text size of the stub is: ARCH before +printf -Os arm 35197 37889 34638 arm64 34883 38159 34479 i386 18571 21657 17025 x86_64 25677 29328 22144 Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-6-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/libstub: Add a basic printf implementationArvind Sankar4-1/+320
Copy vsprintf from arch/x86/boot/printf.c to get a simple printf implementation. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-5-nivedita@alum.mit.edu [ardb: add some missing braces in if...else clauses] Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/libstub: Buffer output of efi_putsArvind Sankar1-6/+13
Use a buffer to convert the string to UTF-16. This will reduce the number of firmware calls required to print the string from one per character to one per string in most cases. Cast the input char to unsigned char before converting to efi_char16_t to avoid sign-extension in case there are any non-ASCII characters in the input. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-4-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/libstub: Rename efi_[char16_]printk to efi_[char16_]putsArvind Sankar3-16/+16
These functions do not support formatting, unlike printk. Rename them to puts to make that clear. Move the implementations of these two functions next to each other. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-3-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-19efi/libstub: Include dependencies of efistub.hArvind Sankar1-0/+5
Add #include directives for include files that efistub.h depends on, instead of relying on them having been included by the C source files prior to efistub.h. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200518190716.751506-2-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-06efi/libstub: Correct comment typosJoe Perches2-2/+2
Fix a couple typos in comments. Signed-off-by: Joe Perches <joe@perches.com> Link: https://lore.kernel.org/r/ec53e67b3ac928922807db3cb1585e911971dadc.1588273612.git.joe@perches.com Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-05efi/libstub: Make efi_printk() input argument const char*Ard Biesheuvel2-13/+8
To help the compiler figure out that efi_printk() will not modify the string it is given, make the input argument type const char*. While at it, simplify the implementation as well. Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-05efi/libstub/x86: Work around LLVM ELF quirk build regressionArd Biesheuvel1-0/+1
When building the x86 EFI stub with Clang, the libstub Makefile rules that manipulate the ELF object files may throw an error like: STUBCPY drivers/firmware/efi/libstub/efi-stub-helper.stub.o strip: drivers/firmware/efi/libstub/efi-stub-helper.stub.o: Failed to find link section for section 10 objcopy: drivers/firmware/efi/libstub/efi-stub-helper.stub.o: Failed to find link section for section 10 This is the result of a LLVM feature [0] where symbol references are stored in a LLVM specific .llvm_addrsig section in a non-transparent way, causing generic ELF tools such as strip or objcopy to choke on them. So force the compiler not to emit these sections, by passing the appropriate command line option. [0] https://sourceware.org/bugzilla/show_bug.cgi?id=23817 Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Sami Tolvanen <samitolvanen@google.com> Reported-by: Arnd Bergmann <arnd@arndb.de> Suggested-by: Fangrui Song <maskray@google.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-05efi/libstub: Fix mixed mode boot issue after macro refactorArvind Sankar1-10/+4
Commit 22090f84bc3f ("efi/libstub: unify EFI call wrappers for non-x86") refactored the macros that are used to provide wrappers for mixed-mode calls on x86, allowing us to boot a 64-bit kernel on 32-bit firmware. Unfortunately, this broke mixed mode boot due to the fact that efi_is_native() is not a macro on x86. All of these macros should go together, so rather than testing each one to see if it is defined, condition the generic macro definitions on a new ARCH_HAS_EFISTUB_WRAPPERS, and remove the wrapper definitions on x86 as well if CONFIG_EFI_MIXED is not enabled. Fixes: 22090f84bc3f ("efi/libstub: unify EFI call wrappers for non-x86") Reported-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200504150248.62482-1-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/libstub: Check return value of efi_parse_optionsArvind Sankar2-8/+27
efi_parse_options can fail if it is unable to allocate space for a copy of the command line. Check the return value to make sure it succeeded. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-12-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/x86: Support builtin command lineArvind Sankar1-4/+8
Add support for the x86 CMDLINE_BOOL and CMDLINE_OVERRIDE configuration options. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-11-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/libstub: Unify initrd loading across architecturesArvind Sankar4-40/+52
Factor out the initrd loading into a common function that can be called both from the generic efi-stub.c and the x86-specific x86-stub.c. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-10-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/x86: Move command-line initrd loading to efi_mainArvind Sankar1-39/+25
Consolidate the initrd loading in efi_main. The command line options now need to be parsed only once. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-9-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/libstub: Upgrade ignored dtb= argument message to errorArvind Sankar1-1/+1
Use efi_err if we ignore a command-line dtb= argument, so that it shows up even on a quiet boot. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-8-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/tpm: Use efi_err for error messagesArvind Sankar1-1/+1
Use efi_err instead of bare efi_printk for error messages. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-7-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/gop: Use efi_err for error messagesArvind Sankar1-5/+5
Use efi_err instead of bare efi_printk for error messages. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-6-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/x86: Use efi_err for error messagesArvind Sankar1-12/+12
Use efi_err instead of bare efi_printk for error messages. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-5-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/libstub: Move pr_efi/pr_efi_err into efi namespaceArvind Sankar9-52/+52
Rename pr_efi to efi_info and pr_efi_err to efi_err to make it more obvious that they are part of the EFI stub and not generic printk infra. Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-4-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/libstub: Add a helper function to split 64-bit valuesArvind Sankar3-22/+23
In several places 64-bit values need to be split up into two 32-bit fields, in order to be backward-compatible with the old 32-bit ABIs. Instead of open-coding this, add a helper function to set a 64-bit value as two 32-bit fields. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-3-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-05-01efi/x86: Use correct size for boot_paramsArvind Sankar1-3/+4
struct boot_params is only 4096 bytes, not 16384. Fix this by using sizeof(struct boot_params) instead of hardcoding the incorrect value. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200430182843.2510180-2-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-25efi/libstub: Re-enable command line initrd loading for x86Ard Biesheuvel1-2/+2
Commit: cf6b83664895a5 ("efi/libstub: Make initrd file loader configurable") inadvertently disabled support on x86 for loading an initrd passed via the initrd= option on the kernel command line. Add X86 to the newly introduced Kconfig option's title and depends declarations, so it gets enabled by default, as before. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Cc: linux-efi@vger.kernel.org
2020-04-24efi: Move arch_tables check to callerArd Biesheuvel1-10/+8
Instead of making match_config_table() test its table_types pointer for NULL-ness, omit the call entirely if no arch_tables pointer was provided to efi_config_parse_tables(). Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi: Clean up config table description arraysArd Biesheuvel2-16/+16
Increase legibility by adding whitespace to the efi_config_table_type_t arrays that describe which EFI config tables we look for when going over the firmware provided list. While at it, replace the 'name' char pointer with a char array, which is more space efficient on relocatable 64-bit kernels, as it avoids a 8 byte pointer and the associated relocation data (24 bytes when using RELA format) Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub/x86: Avoid getter function for efi_is64Ard Biesheuvel1-8/+0
We no longer need to take special care when using global variables in the EFI stub, so switch to a simple symbol reference for efi_is64. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub: Drop __pure getters for EFI stub optionsArd Biesheuvel7-39/+20
The practice of using __pure getter functions to access global variables in the EFI stub dates back to the time when we had to carefully prevent GOT entries from being emitted, because we could not rely on the toolchain to do this for us. Today, we use the hidden visibility pragma for all EFI stub source files, which now all live in the same subdirectory, and we apply a sanity check on the objects, so we can get rid of these getter functions and simply refer to global data objects directly. So switch over the remaining boolean variables carrying options set on the kernel command line. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub: Drop __pure getter for efi_system_tableArd Biesheuvel5-32/+22
The practice of using __pure getter functions to access global variables in the EFI stub dates back to the time when we had to carefully prevent GOT entries from being emitted, because we could not rely on the toolchain to do this for us. Today, we use the hidden visibility pragma for all EFI stub source files, which now all live in the same subdirectory, and we apply a sanity check on the objects, so we can get rid of these getter functions and simply refer to global data objects directly. Start with efi_system_table(), and convert it into a global variable. While at it, make it a pointer-to-const, because we can. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi: Kill __efistub_globalArvind Sankar5-14/+11
Now that both arm and x86 are using the linker script to place the EFI stub's global variables in the correct section, remove __efistub_global. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20200416151227.3360778-4-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/x86: Remove __efistub_global and add relocation checkArvind Sankar2-15/+21
Instead of using __efistub_global to force variables into the .data section, leave them in the .bss but pull the EFI stub's .bss section into .data in the linker script for the compressed kernel. Add relocation checking for x86 as well to catch non-PC-relative relocations that require runtime processing, since the EFI stub does not do any runtime relocation processing. This will catch, for example, data relocations created by static initializers of pointers. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Link: https://lore.kernel.org/r/20200416151227.3360778-3-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/arm: Remove __efistub_global annotationArvind Sankar2-4/+5
Instead of using __efistub_global to force variables into the .data section, leave them in the .bss but pull the EFI stub's .bss section into .data in the linker script for the compressed kernel. Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> Reviewed-by: Ard Biesheuvel <ardb@kernel.org> Link: https://lore.kernel.org/r/20200416151227.3360778-2-nivedita@alum.mit.edu Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub: Move efi_relocate_kernel() into separate source fileArd Biesheuvel4-184/+175
Move efi_relocate_kernel() into a separate source file, so that it only gets pulled into builds for architectures that use it. Since efi_relocate_kernel() is the only user of efi_low_alloc(), let's move that over as well. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub/arm64: Switch to ordinary page allocator for kernel imageArd Biesheuvel1-2/+2
It is no longer necessary to locate the kernel as low as possible in physical memory, and so we can switch from efi_low_alloc() [which is a rather nasty concoction on top of GetMemoryMap()] to a new helper called efi_allocate_pages_aligned(), which simply rounds up the size to account for the alignment, and frees the misaligned pages again. So considering that the kernel can live anywhere in the physical address space, as long as its alignment requirements are met, let's switch to efi_allocate_pages_aligned() to allocate the pages. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-24efi/libstub: Add API function to allocate aligned memoryArd Biesheuvel4-17/+71
Break out the code to create an aligned page allocation from mem.c and move it into a function efi_allocate_pages_aligned() in alignedmem.c. Update efi_allocate_pages() to invoke it unless the minimum alignment equals the EFI page size (4 KB), in which case the ordinary page allocator is sufficient. This way, efi_allocate_pages_aligned() will only be pulled into the build if it is actually being used (which will be on arm64 only in the immediate future) Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-23efi/libstub/arm64: Simplify randomized loading of kernel imageArd Biesheuvel1-27/+5
The KASLR code path in the arm64 version of the EFI stub incorporates some overly complicated logic to randomly allocate a region of the right alignment: there is no need to randomize the placement of the kernel modulo 2 MiB separately from the placement of the 2 MiB aligned allocation itself - we can simply follow the same logic used by the non-randomized placement, which is to allocate at the correct alignment, and only take TEXT_OFFSET into account if it is not a round multiple of the alignment. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2020-04-23efi/libstub/arm64: Replace 'preferred' offset with alignment checkArd Biesheuvel1-37/+25
The notion of a 'preferred' load offset for the kernel dates back to the times when the kernel's primary mapping overlapped with the linear region, and memory below it could not be used at all. Today, the arm64 kernel does not really care where it is loaded in physical memory, as long as the alignment requirements are met, and so there is no point in unconditionally moving the kernel to a new location in memory at boot. Instead, we can - check for a KASLR seed, and randomly reallocate the kernel if one is provided - otherwise, check whether the alignment requirements are met for the current placement of the kernel, and just run it in place if they are - finally, do an ordinary page allocation and reallocate the kernel to a suitably aligned buffer anywhere in memory. By the same reasoning, there is no need to take TEXT_OFFSET into account if it is a round multiple of the minimum alignment, which is the usual case for relocatable kernels with TEXT_OFFSET randomization disabled. Otherwise, it suffices to use the relative misaligment of TEXT_OFFSET when reallocating the kernel. Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
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