kernel/linux.git/arch/x86/include/asm/setup.h, branch v6.6.142

x86/boot/32: De-uglify the 2/3 level paging difference in mk_early_pgtbl_32()

2025-03-09T08:55:03+00:00

commit a62f4ca106fd250e9247decd100f3905131fc1fe upstream Move the ifdeffery out of the function and use proper typedefs to make it work for both 2 and 3 level paging. No functional change. [ bp: Move mk_early_pgtbl_32() declaration into a header. ] Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20231017211722.111059491@linutronix.de Signed-off-by: Greg Kroah-Hartman

x86/head: Mark *_start_kernel() __noreturn

2023-04-14T15:31:24+00:00

Now that start_kernel() is __noreturn, mark its chain of callers __noreturn. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/c2525f96b88be98ee027ee0291d58003036d4120.1681342859.git.jpoimboe@kernel.org

x86/xen: Use clear_bss() for Xen PV guests

2022-07-01T08:57:52+00:00

Instead of clearing the bss area in assembly code, use the clear_bss() function. This requires to pass the start_info address as parameter to xen_start_kernel() in order to avoid the xen_start_info being zeroed again. Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov Reviewed-by: Jan Beulich Reviewed-by: Boris Ostrovsky Link: https://lore.kernel.org/r/20220630071441.28576-2-jgross@suse.com

x86/mm: Fix RESERVE_BRK() for older binutils

2022-06-13T08:15:04+00:00

With binutils 2.26, RESERVE_BRK() causes a build failure: /tmp/ccnGOKZ5.s: Assembler messages: /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: missing ')' /tmp/ccnGOKZ5.s:98: Error: junk at end of line, first unrecognized character is `U' The problem is this line: RESERVE_BRK(early_pgt_alloc, INIT_PGT_BUF_SIZE) Specifically, the INIT_PGT_BUF_SIZE macro which (via PAGE_SIZE's use _AC()) has a "1UL", which makes older versions of the assembler unhappy. Unfortunately the _AC() macro doesn't work for inline asm. Inline asm was only needed here to convince the toolchain to add the STT_NOBITS flag. However, if a C variable is placed in a section whose name is prefixed with ".bss", GCC and Clang automatically set STT_NOBITS. In fact, ".bss..page_aligned" already relies on this trick. So fix the build failure (and simplify the macro) by allocating the variable in C. Also, add NOLOAD to the ".brk" output section clause in the linker script. This is a failsafe in case the ".bss" prefix magic trick ever stops working somehow. If there's a section type mismatch, the GNU linker will force the ".brk" output section to be STT_NOBITS. The LLVM linker will fail with a "section type mismatch" error. Note this also changes the name of the variable from .brk.##name to __brk_##name. The variable names aren't actually used anywhere, so it's harmless. Fixes: a1e2c031ec39 ("x86/mm: Simplify RESERVE_BRK()") Reported-by: Joe Damato Reported-by: Byungchul Park Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Tested-by: Joe Damato Link: https://lore.kernel.org/r/22d07a44c80d8e8e1e82b9a806ddc8c6bbb2606e.1654759036.git.jpoimboe@kernel.org

Merge tag 'x86_asm_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2022-05-24T01:08:46+00:00

Pull x86 asm updates from Borislav Petkov: - A bunch of changes towards streamlining low level asm helpers' calling conventions so that former can be converted to C eventually - Simplify PUSH_AND_CLEAR_REGS so that it can be used at the system call entry paths instead of having opencoded, slightly different variants of it everywhere - Misc other fixes * tag 'x86_asm_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry: Fix register corruption in compat syscall objtool: Fix STACK_FRAME_NON_STANDARD reloc type linkage: Fix issue with missing symbol size x86/entry: Remove skip_r11rcx x86/entry: Use PUSH_AND_CLEAR_REGS for compat x86/entry: Simplify entry_INT80_compat() x86/mm: Simplify RESERVE_BRK() x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS x86/entry: Don't call error_entry() for XENPV x86/entry: Move CLD to the start of the idtentry macro x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() x86/entry: Switch the stack after error_entry() returns x86/traps: Use pt_regs directly in fixup_bad_iret()

x86/mm: Simplify RESERVE_BRK()

2022-05-06T13:26:33+00:00

RESERVE_BRK() reserves data in the .brk_reservation section. The data is initialized to zero, like BSS, so the macro specifies 'nobits' to prevent the data from taking up space in the vmlinux binary. The only way to get the compiler to do that (without putting the variable in .bss proper) is to use inline asm. The macro also has a hack which encloses the inline asm in a discarded function, which allows the size to be passed (global inline asm doesn't allow inputs). Remove the need for the discarded function hack by just stringifying the size rather than supplying it as an input to the inline asm. Signed-off-by: Josh Poimboeuf Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Borislav Petkov Link: https://lore.kernel.org/r/20220506121631.133110232@infradead.org

x86/head/64: Re-enable stack protection

2022-04-06T15:06:55+00:00

Due to 103a4908ad4d ("x86/head/64: Disable stack protection for head$(BITS).o") kernel/head{32,64}.c are compiled with -fno-stack-protector to allow a call to set_bringup_idt_handler(), which would otherwise have stack protection enabled with CONFIG_STACKPROTECTOR_STRONG. While sufficient for that case, there may still be issues with calls to any external functions that were compiled with stack protection enabled that in-turn make stack-protected calls, or if the exception handlers set up by set_bringup_idt_handler() make calls to stack-protected functions. Subsequent patches for SEV-SNP CPUID validation support will introduce both such cases. Attempting to disable stack protection for everything in scope to address that is prohibitive since much of the code, like the SEV-ES #VC handler, is shared code that remains in use after boot and could benefit from having stack protection enabled. Attempting to inline calls is brittle and can quickly balloon out to library/helper code where that's not really an option. Instead, re-enable stack protection for head32.c/head64.c, and make the appropriate changes to ensure the segment used for the stack canary is initialized in advance of any stack-protected C calls. For head64.c: - The BSP will enter from startup_64() and call into C code (startup_64_setup_env()) shortly after setting up the stack, which may result in calls to stack-protected code. Set up %gs early to allow for this safely. - APs will enter from secondary_startup_64*(), and %gs will be set up soon after. There is one call to C code prior to %gs being setup (__startup_secondary_64()), but it is only to fetch 'sme_me_mask' global, so just load 'sme_me_mask' directly instead, and remove the now-unused __startup_secondary_64() function. For head32.c: - BSPs/APs will set %fs to __BOOT_DS prior to any C calls. In recent kernels, the compiler is configured to access the stack canary at %fs:__stack_chk_guard [1], which overlaps with the initial per-cpu '__stack_chk_guard' variable in the initial/"master" .data..percpu area. This is sufficient to allow access to the canary for use during initial startup, so no changes are needed there. [1] 3fb0fdb3bbe7 ("x86/stackprotector/32: Make the canary into a regular percpu variable") [ bp: Massage commit message. ] Suggested-by: Joerg Roedel #for 64-bit %gs set up Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220307213356.2797205-24-brijesh.singh@amd.com

x86/ibt: Dont generate ENDBR in .discard.text

2022-03-15T09:32:42+00:00

Having ENDBR in discarded sections can easily lead to relocations into discarded sections which the linkers aren't really fond of. Objtool also shouldn't generate them, but why tempt fate. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220308154319.054842742@infradead.org

x86/setup: Remove unused RESERVE_BRK_ARRAY()

2021-03-11T10:47:37+00:00

Since a13f2ef168cb ("x86/xen: remove 32-bit Xen PV guest support"), RESERVE_BRK_ARRAY() has no user anymore so drop it. Update related comments too. Signed-off-by: Cao jin Signed-off-by: Borislav Petkov Link: https://lkml.kernel.org/r/20210311083919.27530-1-jojing64@gmail.com

treewide: Convert macro and uses of section(foo) to section("foo")

2020-10-25T21:51:49+00:00

Use a more generic form for __section that requires quotes to avoid complications with clang and gcc differences. Remove the quote operator # from compiler_attributes.h __section macro. Convert all unquoted __section(foo) uses to quoted __section("foo"). Also convert __attribute__((section("foo"))) uses to __section("foo") even if the __attribute__ has multiple list entry forms. Conversion done using the script at: https://lore.kernel.org/lkml/75393e5ddc272dc7403de74d645e6c6e0f4e70eb.camel@perches.com/2-convert_section.pl Signed-off-by: Joe Perches Reviewed-by: Nick Desaulniers Reviewed-by: Miguel Ojeda Signed-off-by: Linus Torvalds