Shorten X86_FEATURE_CLEAR_BHB_LOOP_ON_VMEXIT to
X86_FEATURE_CLEAR_BHB_VMEXIT to make the last column aligned
consistently in the whole file.
There's no need to explain in the name what the mitigation does.
No functional changes.
Suggested-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250415175410.2944032-3-xin@zytor.com
It is a special file with special formatting so remove one whitespace
damage and format newer defines like the rest.
No functional changes.
[ Xin: Do the same to tools/arch/x86/include/asm/cpufeatures.h. ]
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/20250415175410.2944032-2-xin@zytor.com
Whack this thing because:
- the "unknown" handling is done only for this vuln and not for the
others
- it doesn't do anything besides reporting things differently. It
doesn't apply any mitigations - it is simply causing unnecessary
complications to the code which don't bring anything besides
maintenance overhead to what is already a very nasty spaghetti pile
- all the currently unaffected CPUs can also be in "unknown" status so
there's no need for special handling here
so get rid of it.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: David Kaplan <david.kaplan@amd.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Link: https://lore.kernel.org/r/20250414150951.5345-1-bp@kernel.org
Turn thread.fpu into a pointer. Since most FPU code internals work by passing
around the FPU pointer already, the code generation impact is small.
This allows us to remove the old kludge of task_struct being variable size:
struct task_struct {
...
/*
* New fields for task_struct should be added above here, so that
* they are included in the randomized portion of task_struct.
*/
randomized_struct_fields_end
/* CPU-specific state of this task: */
struct thread_struct thread;
/*
* WARNING: on x86, 'thread_struct' contains a variable-sized
* structure. It *MUST* be at the end of 'task_struct'.
*
* Do not put anything below here!
*/
};
... which creates a number of problems, such as requiring thread_struct to be
the last member of the struct - not allowing it to be struct-randomized, etc.
But the primary motivation is to allow the decoupling of task_struct from
hardware details (<asm/processor.h> in particular), and to eventually allow
the per-task infrastructure:
DECLARE_PER_TASK(type, name);
...
per_task(current, name) = val;
... which requires task_struct to be a constant size struct.
The fpu_thread_struct_whitelist() quirk to hardened usercopy can be removed,
now that the FPU structure is not embedded in the task struct anymore, which
reduces text footprint a bit.
Fixed-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Chang S. Bae <chang.seok.bae@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250409211127.3544993-4-mingo@kernel.org
Since objtool's inception, frame pointer warnings have been manually
silenced for __arch_hweight*() to allow those functions' inline asm to
avoid using ASM_CALL_CONSTRAINT.
The potentially dubious reasoning for that decision over nine years ago
was that since !X86_FEATURE_POPCNT is exceedingly rare, it's not worth
hurting the code layout for a function call that will never happen on
the vast majority of systems.
However, those functions actually started using ASM_CALL_CONSTRAINT with
the following commit:
194a613088 ("x86/hweight: Use ASM_CALL_CONSTRAINT in inline asm()")
And rightfully so, as it makes the code correct. ASM_CALL_CONSTRAINT
will soon have no effect for non-FP configs anyway.
With ASM_CALL_CONSTRAINT in place, ANNOTATE_IGNORE_ALTERNATIVE no longer
has a purpose for the hweight functions. Remove it.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/e7070dba3278c90f1a836b16157dcd34ccd21e21.1744318586.git.jpoimboe@kernel.org
Refer __percpu_prefix to __force_percpu_prefix to avoid duplicate
definition. While there, slightly reorder definitions to a more
logical sequence, remove unneeded double quotes and move misplaced
comment to the right place.
No functional changes intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Link: https://lore.kernel.org/r/20250411093130.81389-1-ubizjak@gmail.com
RIP_REL_REF() is used in non-PIC C code that is called very early,
before the kernel virtual mapping is up, which is the mapping that the
linker expects. It is currently used in two different ways:
- to refer to the value of a global variable, including as an lvalue in
assignments;
- to take the address of a global variable via the mapping that the code
currently executes at.
The former case is only needed in non-PIC code, as PIC code will never
use absolute symbol references when the address of the symbol is not
being used. But taking the address of a variable in PIC code may still
require extra care, as a stack allocated struct assignment may be
emitted as a memcpy() from a statically allocated copy in .rodata.
For instance, this
void startup_64_setup_gdt_idt(void)
{
struct desc_ptr startup_gdt_descr = {
.address = (__force unsigned long)gdt_page.gdt,
.size = GDT_SIZE - 1,
};
may result in an absolute symbol reference in PIC code, even though the
struct is allocated on the stack and populated at runtime.
To address this case, make rip_rel_ptr() accessible in PIC code, and
update any existing uses where the address of a global variable is
taken using RIP_REL_REF.
Once all code of this nature has been moved into arch/x86/boot/startup
and built with -fPIC, RIP_REL_REF() can be retired, and only
rip_rel_ptr() will remain.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250410134117.3713574-14-ardb+git@google.com
This name is actively confusing as well, because the simple text_poke*()
APIs use MM-switching based code patching, while text_poke_queue()
is part of the INT3 based text_poke_int3_*() machinery that is an
additional layer of functionality on top of regular text_poke*() functionality.
Rename it to smp_text_poke_batch_add() to make it clear which layer
it belongs to.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250411054105.2341982-17-mingo@kernel.org
This name is actively confusing as well, because the simple text_poke*()
APIs use MM-switching based code patching, while text_poke_finish()
is part of the INT3 based text_poke_int3_*() machinery that is an
additional layer of functionality on top of regular text_poke*() functionality.
Rename it to smp_text_poke_batch_finish() to make it clear which layer
it belongs to.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250411054105.2341982-16-mingo@kernel.org
Pull misc x86 fixes from Ingo Molnar:
- Fix CPU topology related regression that limited Xen PV guests to a
single CPU
- Fix ancient e820__register_nosave_regions() bugs that were causing
problems with kexec's artificial memory maps
- Fix an S4 hibernation crash caused by two missing ENDBR's that were
mistakenly removed in a recent commit
- Fix a resctrl serialization bug
- Fix early_printk documentation and comments
- Fix RSB bugs, combined with preparatory updates to better match the
code to vendor recommendations.
- Add RSB mitigation document
- Fix/update documentation
- Fix the erratum_1386_microcode[] table to be NULL terminated
* tag 'x86-urgent-2025-04-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/ibt: Fix hibernate
x86/cpu: Avoid running off the end of an AMD erratum table
Documentation/x86: Zap the subsection letters
Documentation/x86: Update the naming of CPU features for /proc/cpuinfo
x86/bugs: Add RSB mitigation document
x86/bugs: Don't fill RSB on context switch with eIBRS
x86/bugs: Don't fill RSB on VMEXIT with eIBRS+retpoline
x86/bugs: Fix RSB clearing in indirect_branch_prediction_barrier()
x86/bugs: Use SBPB in write_ibpb() if applicable
x86/bugs: Rename entry_ibpb() to write_ibpb()
x86/early_printk: Use 'mmio32' for consistency, fix comments
x86/resctrl: Fix rdtgroup_mkdir()'s unlocked use of kernfs_node::name
x86/e820: Fix handling of subpage regions when calculating nosave ranges in e820__register_nosave_regions()
x86/acpi: Don't limit CPUs to 1 for Xen PV guests due to disabled ACPI
