Commit Graph

982685 Commits

Author SHA1 Message Date
Thomas Gleixner
cd1a41ceba softirq: Move __ARCH_HAS_DO_SOFTIRQ to Kconfig
To prepare for inlining do_softirq_own_stack() replace
__ARCH_HAS_DO_SOFTIRQ with a Kconfig switch and select it in the affected
architectures.

This allows in the next step to move the function prototype and the inline
stub into a seperate asm-generic header file which is required to avoid
include recursion.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.181713427@linutronix.de
2021-02-10 23:34:16 +01:00
Thomas Gleixner
624db9eabc x86: Select CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK
Now that all invocations of irq_exit_rcu() happen on the irq stack, turn on
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK which causes the core code to invoke
__do_softirq() directly without going through do_softirq_own_stack().

That means do_softirq_own_stack() is only invoked from task context which
means it can't be on the irq stack. Remove the conditional from
run_softirq_on_irqstack_cond() and rename the function accordingly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002513.068033456@linutronix.de
2021-02-10 23:34:16 +01:00
Thomas Gleixner
52d743f3b7 x86/softirq: Remove indirection in do_softirq_own_stack()
Use the new inline stack switching and remove the old ASM indirect call
implementation.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.972714001@linutronix.de
2021-02-10 23:34:15 +01:00
Thomas Gleixner
359f01d181 x86/entry: Use run_sysvec_on_irqstack_cond() for XEN upcall
To avoid yet another macro implementation reuse the existing
run_sysvec_on_irqstack_cond() and move the set_irq_regs() handling into the
called function. Makes the code even simpler.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.869753106@linutronix.de
2021-02-10 23:34:15 +01:00
Thomas Gleixner
5b51e1db9b x86/entry: Convert device interrupts to inline stack switching
Convert device interrupts to inline stack switching by replacing the
existing macro implementation with the new inline version. Tweak the
function signature of the actual handler function to have the vector
argument as u32. That allows the inline macro to avoid extra intermediates
and lets the compiler be smarter about the whole thing.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.769728139@linutronix.de
2021-02-10 23:34:15 +01:00
Thomas Gleixner
569dd8b4eb x86/entry: Convert system vectors to irq stack macro
To inline the stack switching and to prepare for enabling
CONFIG_HAVE_IRQ_EXIT_ON_IRQ_STACK provide a macro template for system
vectors and device interrupts and convert the system vectors over to it.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.676197354@linutronix.de
2021-02-10 23:34:15 +01:00
Thomas Gleixner
a0cfc74d0b x86/irq: Provide macro for inlining irq stack switching
The effort to make the ASM entry code slim and unified moved the irq stack
switching out of the low level ASM code so that the whole return from
interrupt work and state handling can be done in C and the ASM code just
handles the low level details of entry and exit.

This ended up being a suboptimal implementation for various reasons
(including tooling). The main pain points are:

 - The indirect call which is expensive thanks to retpoline

 - The inability to stay on the irq stack for softirq processing on return
   from interrupt

 - The fact that the stack switching code ends up being an easy to target
   exploit gadget.

Prepare for inlining the stack switching logic into the C entry points by
providing a ASM macro which contains the guts of the switching mechanism:

  1) Store RSP at the top of the irq stack
  2) Switch RSP to the irq stack
  3) Invoke code
  4) Pop the original RSP back

Document the unholy asm() logic while at it to reduce the amount of head
scratching required a half year from now.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.578371068@linutronix.de
2021-02-10 23:34:14 +01:00
Thomas Gleixner
3c5e0267ec x86/apic: Split out spurious handling code
sysvec_spurious_apic_interrupt() calls into the handling body of
__spurious_interrupt() which is not obvious as that function is declared
inside the DEFINE_IDTENTRY_IRQ(spurious_interrupt) macro.

As __spurious_interrupt() is currently always inlined this ends up with two
copies of the same code for no reason.

Split the handling function out and invoke it from both entry points.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.469379641@linutronix.de
2021-02-10 23:34:14 +01:00
Thomas Gleixner
951c2a51ae x86/irq/64: Adjust the per CPU irq stack pointer by 8
The per CPU hardirq_stack_ptr contains the pointer to the irq stack in the
form that it is ready to be assigned to [ER]SP so that the first push ends
up on the top entry of the stack.

But the stack switching on 64 bit has the following rules:

    1) Store the current stack pointer (RSP) in the top most stack entry
       to allow the unwinder to link back to the previous stack

    2) Set RSP to the top most stack entry

    3) Invoke functions on the irq stack

    4) Pop RSP from the top most stack entry (stored in #1) so it's back
       to the original stack.

That requires all stack switching code to decrement the stored pointer by 8
in order to be able to store the current RSP and then set RSP to that
location. That's a pointless exercise.

Do the -8 adjustment right when storing the pointer and make the data type
a void pointer to avoid confusion vs. the struct irq_stack data type which
is on 64bit only used to declare the backing store. Move the definition
next to the inuse flag so they likely end up in the same cache
line. Sticking them into a struct to enforce it is a seperate change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.354260928@linutronix.de
2021-02-10 23:34:14 +01:00
Thomas Gleixner
e7f8900179 x86/irq: Sanitize irq stack tracking
The recursion protection for hard interrupt stacks is an unsigned int per
CPU variable initialized to -1 named __irq_count. 

The irq stack switching is only done when the variable is -1, which creates
worse code than just checking for 0. When the stack switching happens it
uses this_cpu_add/sub(1), but there is no reason to do so. It simply can
use straight writes. This is a historical leftover from the low level ASM
code which used inc and jz to make a decision.

Rename it to hardirq_stack_inuse, make it a bool and use plain stores.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210210002512.228830141@linutronix.de
2021-02-10 23:34:13 +01:00
Thomas Gleixner
15f720aabe x86/entry: Fix instrumentation annotation
Embracing a callout into instrumentation_begin() / instrumentation_begin()
does not really make sense. Make the latter instrumentation_end().

Fixes: 2f6474e463 ("x86/entry: Switch XEN/PV hypercall entry to IDTENTRY")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20210210002512.106502464@linutronix.de
2021-02-10 23:34:13 +01:00
Thomas Gleixner
4dc1d28ce2 Merge branch 'objtool/core' into x86/entry
to base the irq stack modifications on.
2021-02-10 21:16:44 +01:00
Peter Zijlstra
aafeb14e9d objtool: Support stack-swizzle
Natively support the stack swizzle pattern:

	mov %rsp, (%[tos])
	mov %[tos], %rsp
	...
	pop %rsp

It uses the vals[] array to link the first two stack-ops, and detect
the SP to SP_INDIRECT swizzle.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:52 +01:00
Peter Zijlstra
2a51282984 objtool,x86: Additionally decode: mov %rsp, (%reg)
Where we already decode: mov %rsp, %reg, also decode mov %rsp, (%reg).

Nothing should match for this new stack-op.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:52 +01:00
Peter Zijlstra
87ccc826bf x86/unwind/orc: Change REG_SP_INDIRECT
Currently REG_SP_INDIRECT is unused but means (%rsp + offset),
change it to mean (%rsp) + offset.

The reason is that we're going to swizzle stack in the middle of a C
function with non-trivial stack footprint. This means that when the
unwinder finds the ToS, it needs to dereference it (%rsp) and then add
the offset to the next frame, resulting in: (%rsp) + offset

This is somewhat unfortunate, since REG_BP_INDIRECT is used (by DRAP)
and thus needs to retain the current (%rbp + offset).

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-02-10 20:53:51 +01:00
Josh Poimboeuf
9077c016a3 x86/power: Support objtool validation in hibernate_asm_64.S
The OBJECT_FILES_NON_STANDARD annotation is used to tell objtool to
ignore a file.  File-level ignores won't work when validating vmlinux.o.

Instead, convert restore_image() and core_restore_code() to be ELF
functions.  Their code is conventional enough for objtool to be able to
understand them.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/974f8ceb5385e470f72e93974c70ab5c894bb0dc.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:04 -06:00
Josh Poimboeuf
125f0b7d24 x86/power: Move restore_registers() to top of the file
Because restore_registers() is page-aligned, the assembler inexplicably
adds an unreachable jump from after the end of the previous function to
the beginning of restore_registers().

That confuses objtool, understandably.  It also creates significant text
fragmentation.  As a result, most of the object file is wasted text
(nops).

Move restore_registers() to the beginning of the file to both prevent
the text fragmentation and avoid the dead jump instruction.

$ size /tmp/hibernate_asm_64.before.o /tmp/hibernate_asm_64.after.o
   text	   data	    bss	    dec	    hex	filename
   4415	      0	      0	   4415	   113f	/tmp/hibernate_asm_64.before.o
    524	      0	      0	    524	    20c	/tmp/hibernate_asm_64.after.o

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8c7f634201d26453d73fe55032cbbdc05d004387.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:04 -06:00
Josh Poimboeuf
b682369d47 x86/power: Annotate indirect branches as safe
These indirect jumps are harmless; annotate them to make objtool's
retpoline validation happy.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/ba7a141c98f2c09c255b19bf78ee4a5f45d4ecb6.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:04 -06:00
Josh Poimboeuf
aeb818fcc9 x86/acpi: Support objtool validation in wakeup_64.S
The OBJECT_FILES_NON_STANDARD annotation is used to tell objtool to
ignore a file.  File-level ignores won't work when validating vmlinux.o.

Instead, tell objtool to ignore do_suspend_lowlevel() directly with the
STACK_FRAME_NON_STANDARD annotation.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/269eda576c53bc9ecc8167c211989111013a67aa.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:03 -06:00
Josh Poimboeuf
f83d1a0190 x86/acpi: Annotate indirect branch as safe
This indirect jump is harmless; annotate it to keep objtool's retpoline
validation happy.

Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/a7288e7043265d95c1a5d64f9fd751ead4854bdc.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:03 -06:00
Josh Poimboeuf
7cae4b1cf1 x86/ftrace: Support objtool vmlinux.o validation in ftrace_64.S
With objtool vmlinux.o validation of return_to_handler(), now that
objtool has visibility inside the retpoline, jumping from EMPTY state to
a proper function state results in a stack state mismatch.

return_to_handler() is actually quite normal despite the underlying
magic.  Just annotate it as a normal function.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/14f48e623f61dbdcd84cf27a56ed8ccae73199ef.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:02 -06:00
Josh Poimboeuf
82694854ca x86/xen/pvh: Annotate indirect branch as safe
This indirect jump is harmless; annotate it to keep objtool's retpoline
validation happy.

Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/4797c72a258b26e06741c58ccd4a75c42db39c1d.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:02 -06:00
Josh Poimboeuf
f4b4bc10b0 x86/xen: Support objtool vmlinux.o validation in xen-head.S
The Xen hypercall page is filled with zeros, causing objtool to fall
through all the empty hypercall functions until it reaches a real
function, resulting in a stack state mismatch.

The build-time contents of the hypercall page don't matter because the
page gets rewritten by the hypervisor.  Make it more palatable to
objtool by making each hypervisor function a true empty function, with
nops and a return.

Cc: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0883bde1d7a1fb3b6a4c952bc0200e873752f609.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:02 -06:00
Josh Poimboeuf
cde07a4e44 x86/xen: Support objtool validation in xen-asm.S
The OBJECT_FILES_NON_STANDARD annotation is used to tell objtool to
ignore a file.  File-level ignores won't work when validating vmlinux.o.

Tweak the ELF metadata and unwind hints to allow objtool to follow the
code.

Cc: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8b042a09c69e8645f3b133ef6653ba28f896807d.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:33:01 -06:00
Josh Poimboeuf
c26acfbbfb objtool: Add xen_start_kernel() to noreturn list
xen_start_kernel() doesn't return.  Annotate it as such so objtool can
follow the code flow.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/930deafa89256c60b180442df59a1bbae48f30ab.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
b735bd3e68 objtool: Combine UNWIND_HINT_RET_OFFSET and UNWIND_HINT_FUNC
The ORC metadata generated for UNWIND_HINT_FUNC isn't actually very
func-like.  With certain usages it can cause stack state mismatches
because it doesn't set the return address (CFI_RA).

Also, users of UNWIND_HINT_RET_OFFSET no longer need to set a custom
return stack offset.  Instead they just need to specify a func-like
situation, so the current ret_offset code is hacky for no good reason.

Solve both problems by simplifying the RET_OFFSET handling and
converting it into a more useful UNWIND_HINT_FUNC.

If we end up needing the old 'ret_offset' functionality again in the
future, we should be able to support it pretty easily with the addition
of a custom 'sp_offset' in UNWIND_HINT_FUNC.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/db9d1f5d79dddfbb3725ef6d8ec3477ad199948d.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
081df94301 objtool: Add asm version of STACK_FRAME_NON_STANDARD
To be used for adding asm functions to the ignore list.  The "aw" is
needed to help the ELF section metadata match GCC-created sections.
Otherwise the linker creates duplicate sections instead of combining
them.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/8faa476f9a5ac89af27944ec184c89f95f3c6c49.1611263462.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
ecf11ba4d0 objtool: Assume only ELF functions do sibling calls
There's an inconsistency in how sibling calls are detected in
non-function asm code, depending on the scope of the object.  If the
target code is external to the object, objtool considers it a sibling
call.  If the target code is internal but not a function, objtool
*doesn't* consider it a sibling call.

This can cause some inconsistencies between per-object and vmlinux.o
validation.

Instead, assume only ELF functions can do sibling calls.  This generally
matches existing reality, and makes sibling call validation consistent
between vmlinux.o and per-object.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/0e9ab6f3628cc7bf3bde7aa6762d54d7df19ad78.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:12:00 -06:00
Josh Poimboeuf
18660698a3 x86/ftrace: Add UNWIND_HINT_FUNC annotation for ftrace_stub
Prevent an unreachable objtool warning after the sibling call detection
gets improved.  ftrace_stub() is basically a function, annotate it as
such.

Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/6845e1b2fb0723a95740c6674e548ba38c5ea489.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
31a7424bc5 objtool: Support retpoline jump detection for vmlinux.o
Objtool converts direct retpoline jumps to type INSN_JUMP_DYNAMIC, since
that's what they are semantically.

That conversion doesn't work in vmlinux.o validation because the
indirect thunk function is present in the object, so the intra-object
jump check succeeds before the retpoline jump check gets a chance.

Rearrange the checks: check for a retpoline jump before checking for an
intra-object jump.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/4302893513770dde68ddc22a9d6a2a04aca491dd.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
34ca59e109 objtool: Fix ".cold" section suffix check for newer versions of GCC
With my version of GCC 9.3.1 the ".cold" subfunctions no longer have a
numbered suffix, so the trailing period is no longer there.

Presumably this doesn't yet trigger a user-visible bug since most of the
subfunction detection logic is duplicated.   I only found it when
testing vmlinux.o validation.

Fixes: 54262aa283 ("objtool: Fix sibling call detection")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/ca0b5a57f08a2fbb48538dd915cc253b5edabb40.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
1f9a1b7494 objtool: Fix retpoline detection in asm code
The JMP_NOSPEC macro branches to __x86_retpoline_*() rather than the
__x86_indirect_thunk_*() wrappers used by C code.  Detect jumps to
__x86_retpoline_*() as retpoline dynamic jumps.

Presumably this doesn't trigger a user-visible bug.  I only found it
when testing vmlinux.o validation.

Fixes: 39b735332c ("objtool: Detect jumps to retpoline thunks")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/31f5833e2e4f01e3d755889ac77e3661e906c09f.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Josh Poimboeuf
6f567c9300 objtool: Fix error handling for STD/CLD warnings
Actually return an error (and display a backtrace, if requested) for
directional bit warnings.

Fixes: 2f0f9e9ad7 ("objtool: Add Direction Flag validation")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/dc70f2adbc72f09526f7cab5b6feb8bf7f6c5ad4.1611263461.git.jpoimboe@redhat.com
2021-01-26 11:11:59 -06:00
Borislav Petkov
0bab9cb2d9 x86/entry: Remove put_ret_addr_in_rdi THUNK macro argument
That logic is unused since

  320100a5ff ("x86/entry: Remove the TRACE_IRQS cruft")

Remove it.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/YAAszZJ2GcIYZmB5@hirez.programming.kicks-ass.net
2021-01-19 11:06:14 +01:00
Nick Desaulniers
5e6dca82bc x86/entry: Emit a symbol for register restoring thunk
Arnd found a randconfig that produces the warning:

  arch/x86/entry/thunk_64.o: warning: objtool: missing symbol for insn at
  offset 0x3e

when building with LLVM_IAS=1 (Clang's integrated assembler). Josh
notes:

  With the LLVM assembler not generating section symbols, objtool has no
  way to reference this code when it generates ORC unwinder entries,
  because this code is outside of any ELF function.

  The limitation now being imposed by objtool is that all code must be
  contained in an ELF symbol.  And .L symbols don't create such symbols.

  So basically, you can use an .L symbol *inside* a function or a code
  segment, you just can't use the .L symbol to contain the code using a
  SYM_*_START/END annotation pair.

Fangrui notes that this optimization is helpful for reducing image size
when compiling with -ffunction-sections and -fdata-sections. I have
observed on the order of tens of thousands of symbols for the kernel
images built with those flags.

A patch has been authored against GNU binutils to match this behavior
of not generating unused section symbols ([1]), so this will
also become a problem for users of GNU binutils once they upgrade to 2.36.

Omit the .L prefix on a label so that the assembler will emit an entry
into the symbol table for the label, with STB_LOCAL binding. This
enables objtool to generate proper unwind info here with LLVM_IAS=1 or
GNU binutils 2.36+.

 [ bp: Massage commit message. ]

Reported-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Suggested-by: Borislav Petkov <bp@alien8.de>
Suggested-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20210112194625.4181814-1-ndesaulniers@google.com
Link: https://github.com/ClangBuiltLinux/linux/issues/1209
Link: https://reviews.llvm.org/D93783
Link: https://sourceware.org/binutils/docs/as/Symbol-Names.html
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=d1bcae833b32f1408485ce69f844dcd7ded093a8 [1]
2021-01-14 17:18:25 +01:00
Josh Poimboeuf
c9c324dc22 objtool: Support stack layout changes in alternatives
The ORC unwinder showed a warning [1] which revealed the stack layout
didn't match what was expected.  The problem was that paravirt patching
had replaced "CALL *pv_ops.irq.save_fl" with "PUSHF;POP".  That changed
the stack layout between the PUSHF and the POP, so unwinding from an
interrupt which occurred between those two instructions would fail.

Part of the agreed upon solution was to rework the custom paravirt
patching code to use alternatives instead, since objtool already knows
how to read alternatives (and converging runtime patching infrastructure
is always a good thing anyway).  But the main problem still remains,
which is that runtime patching can change the stack layout.

Making stack layout changes in alternatives was disallowed with commit
7117f16bf4 ("objtool: Fix ORC vs alternatives"), but now that paravirt
is going to be doing it, it needs to be supported.

One way to do so would be to modify the ORC table when the code gets
patched.  But ORC is simple -- a good thing! -- and it's best to leave
it alone.

Instead, support stack layout changes by "flattening" all possible stack
states (CFI) from parallel alternative code streams into a single set of
linear states.  The only necessary limitation is that CFI conflicts are
disallowed at all possible instruction boundaries.

For example, this scenario is allowed:

          Alt1                    Alt2                    Alt3

   0x00   CALL *pv_ops.save_fl    CALL xen_save_fl        PUSHF
   0x01                                                   POP %RAX
   0x02                                                   NOP
   ...
   0x05                           NOP
   ...
   0x07   <insn>

The unwind information for offset-0x00 is identical for all 3
alternatives.  Similarly offset-0x05 and higher also are identical (and
the same as 0x00).  However offset-0x01 has deviating CFI, but that is
only relevant for Alt3, neither of the other alternative instruction
streams will ever hit that offset.

This scenario is NOT allowed:

          Alt1                    Alt2

   0x00   CALL *pv_ops.save_fl    PUSHF
   0x01                           NOP6
   ...
   0x07   NOP                     POP %RAX

The problem here is that offset-0x7, which is an instruction boundary in
both possible instruction patch streams, has two conflicting stack
layouts.

[ The above examples were stolen from Peter Zijlstra. ]

The new flattened CFI array is used both for the detection of conflicts
(like the second example above) and the generation of linear ORC
entries.

BTW, another benefit of these changes is that, thanks to some related
cleanups (new fake nops and alt_group struct) objtool can finally be rid
of fake jumps, which were a constant source of headaches.

[1] https://lkml.kernel.org/r/20201111170536.arx2zbn4ngvjoov7@treble

Cc: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:54 -06:00
Josh Poimboeuf
b23cc71c62 objtool: Add 'alt_group' struct
Create a new struct associated with each group of alternatives
instructions.  This will help with the removal of fake jumps, and more
importantly with adding support for stack layout changes in
alternatives.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:48 -06:00
Josh Poimboeuf
ab4e0744e9 objtool: Refactor ORC section generation
Decouple ORC entries from instructions.  This simplifies the
control/data flow, and is going to make it easier to support alternative
instructions which change the stack layout.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-14 09:53:42 -06:00
Vasily Gorbik
5ed934e57e x86/insn: Fix vector instruction decoding on big endian cross-compiles
Running instruction decoder posttest on an s390 host with an x86 target
with allyesconfig shows errors. Instructions used in a couple of kernel
objects could not be correctly decoded on big endian system.

  insn_decoder_test: warning: objdump says 6 bytes, but insn_get_length() says 5
  insn_decoder_test: warning: Found an x86 instruction decoder bug, please report this.
  insn_decoder_test: warning: ffffffff831eb4e1:    62 d1 fd 48 7f 04 24    vmovdqa64 %zmm0,(%r12)
  insn_decoder_test: warning: objdump says 7 bytes, but insn_get_length() says 6
  insn_decoder_test: warning: Found an x86 instruction decoder bug, please report this.
  insn_decoder_test: warning: ffffffff831eb4e8:    62 51 fd 48 7f 44 24 01         vmovdqa64 %zmm8,0x40(%r12)
  insn_decoder_test: warning: objdump says 8 bytes, but insn_get_length() says 6

This is because in a few places instruction field bytes are set directly
with further usage of "value". To address that introduce and use a
insn_set_byte() helper, which correctly updates "value" on big endian
systems.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:17 -06:00
Vasily Gorbik
7786032e52 objtool: Rework header include paths
Currently objtool headers are being included either by their base name
or included via ../ from a parent directory. In case of a base name usage:

 #include "warn.h"
 #include "arch_elf.h"

it does not make it apparent from which directory the file comes from.
To make it slightly better, and actually to avoid name clashes some arch
specific files have "arch_" suffix. And files from an arch folder have
to revert to including via ../ e.g:
 #include "../../elf.h"

With additional architectures support and the code base growth there is
a need for clearer headers naming scheme for multiple reasons:
1. to make it instantly obvious where these files come from (objtool
   itself / objtool arch|generic folders / some other external files),
2. to avoid name clashes of objtool arch specific headers, potential
   obtool arch generic headers and the system header files (there is
   /usr/include/elf.h already),
3. to avoid ../ includes and improve code readability.
4. to give a warm fuzzy feeling to developers who are mostly kernel
   developers and are accustomed to linux kernel headers arranging
   scheme.

Doesn't this make it instantly obvious where are these files come from?

 #include <objtool/warn.h>
 #include <arch/elf.h>

And doesn't it look nicer to avoid ugly ../ includes? Which also
guarantees this is elf.h from the objtool and not /usr/include/elf.h.

 #include <objtool/elf.h>

This patch defines and implements new objtool headers arranging
scheme. Which is:
- all generic headers go to include/objtool (similar to include/linux)
- all arch headers go to arch/$(SRCARCH)/include/arch (to get arch
  prefix). This is similar to linux arch specific "asm/*" headers but we
  are not abusing "asm" name and calling it what it is. This also helps
  to prevent name clashes (arch is not used in system headers or kernel
  exports).

To bring objtool to this state the following things are done:
1. current top level tools/objtool/ headers are moved into
   include/objtool/ subdirectory,
2. arch specific headers, currently only arch/x86/include/ are moved into
   arch/x86/include/arch/ and were stripped of "arch_" suffix,
3. new -I$(srctree)/tools/objtool/include include path to make
   includes like <objtool/warn.h> possible,
4. rewriting file includes,
5. make git not to ignore include/objtool/ subdirectory.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:14 -06:00
Vasily Gorbik
8bfe273238 objtool: Fix x86 orc generation on big endian cross-compiles
Correct objtool orc generation endianness problems to enable fully
functional x86 cross-compiles on big endian hardware.

Introduce bswap_if_needed() macro, which does a byte swap if target
endianness doesn't match the host, i.e. cross-compilation for little
endian on big endian and vice versa.  The macro is used for conversion
of multi-byte values which are read from / about to be written to a
target native endianness ELF file.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:13 -06:00
Martin Schwidefsky
a1a664ece5 objtool: Fix reloc generation on big endian cross-compiles
Relocations generated in elf_rebuild_rel[a]_reloc_section() are broken
if objtool is built and run on a big endian system.

The following errors pop up during x86 cross-compilation:

  x86_64-9.1.0-ld: fs/efivarfs/inode.o: bad reloc symbol index (0x2000000 >= 0x22) for offset 0 in section `.orc_unwind_ip'
  x86_64-9.1.0-ld: final link failed: bad value

Convert those functions to use gelf_update_rel[a](), similar to what
elf_write_reloc() does.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:12 -06:00
Martin Schwidefsky
1d509f2a6e x86/insn: Support big endian cross-compiles
The x86 instruction decoder code is shared across the kernel source and
the tools. Currently objtool seems to be the only tool from build tools
needed which breaks x86 cross-compilation on big endian systems. Make
the x86 instruction decoder build host endianness agnostic to support
x86 cross-compilation and enable objtool to implement endianness
awareness for big endian architectures support.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:11 -06:00
Vasily Gorbik
c8d7b7e592 x86/tools: Use tools headers for instruction decoder selftests
Currently the x86 instruction decoder is used from:
- the kernel itself,
- from tools like objtool and perf,
- within x86 tools, i.e. instruction decoder selftests.

The first two cases are similar, because tools headers try to mimic
kernel headers.

Instruction decoder selftests include some of the kernel headers
directly, including uapi headers. This works until headers dependencies
are kept to a minimum and tools are not cross-compiled. Since the goal
of the x86 instruction decoder selftests is not to verify uapi headers,
move it to using tools headers, like is already done for vdso2c tool,
mkpiggy and other tools in arch/x86/boot/.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:11 -06:00
Julien Thierry
201ef5a974 objtool: Make SP memory operation match PUSH/POP semantics
Architectures without PUSH/POP instructions will always access the stack
though memory operations (SRC/DEST_INDIRECT). Make those operations have
the same effect on the CFA as PUSH/POP, with no stack pointer
modification.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:10 -06:00
Julien Thierry
468af56a7b objtool: Support addition to set CFA base
On arm64, the compiler can set the frame pointer either
with a move operation or with and add operation like:

    add (SP + constant), BP

For a simple move operation, the CFA base is changed from SP to BP.
Handle also changing the CFA base when the frame pointer is set with
an addition instruction.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:10 -06:00
Julien Thierry
fb084fde0c objtool: Fully validate the stack frame
A valid stack frame should contain both the return address and the
previous frame pointer value.

On x86, the return value is placed on the stack by the calling
instructions. On other architectures, the callee needs to explicitly
save the return address on the stack.

Add the necessary checks to verify a function properly sets up all the
elements of the stack frame.

Signed-off-by: Julien Thierry <jthierry@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
2021-01-13 18:13:09 -06:00
Linus Torvalds
7c53f6b671 Linux 5.11-rc3 2021-01-10 14:34:50 -08:00
Linus Torvalds
20210a9846 Kbuild fixes for v5.11
- Search for <ncurses.h> in the default header path of HOSTCC
 
  - Tweak the option order to be kind to old BSD awk
 
  - Remove 'kvmconfig' and 'xenconfig' shorthands
 
  - Fix documentation
 -----BEGIN PGP SIGNATURE-----
 
 iQJJBAABCgAzFiEEbmPs18K1szRHjPqEPYsBB53g2wYFAl/7YsgVHG1hc2FoaXJv
 eUBrZXJuZWwub3JnAAoJED2LAQed4NsGMywQAKXnzI0nOsJWCsRNhYaOvgR/xmEl
 Tu/E+fN6aL/BGtIfkrdJzYRCa5UWONYMQuACvDhXarR1/Stkag9XyWY+rRTHK6In
 rYGb2NmjKUsJ4mtZtpPY7lyMgizZJX63Ba8m+Np8U3dpHuCk2OncOJFszJAiPqoN
 RbJiUNTT8F0/W827kvDcbdWc8iiXN75mqblFZQBSG71kiv/l/3Jsz/FE5980pGfv
 XfZbokOKBGpEAnzHCt4wfodlTQxsezzbgkrzquVhosJYidXcl3VMnoJMfPFFJwIv
 pxgIyrdUxgyuM3iqwymiXxJtv+wVUC9lTEgYp4KgIy0kj2ACe59u6wAcjSDoHWEu
 pImhidGu0dZTrIltT4IE2WoqsFqtjkMCAM1DvLlgPS8GROL0IK0l9AnXAyCUoSYE
 RMhYO3K9G6z0PGvNGJcxPttih8na/hLjvUwbFWUGlltadmYqSLA16MO4c3NOgqMR
 RbLJ5K6c/tKe9ktW8f+FVJlcRnEebEbG9hzQLG5W/umEesxUQHFVe44nmCEJkyVB
 tQdCXCqiBOcSoJC+pYceuGG/vUhX+Nmm+zMyI5pTwAvBL7Yx4Ef4HOIMlbKCLT6z
 HsC/CtfIb1IEfNbKq+9nkHZRnO8lNAORJmyFzTwDYDQJWvNTKvDviJo5V7i9QfEm
 0WVOr9qCIlOWJvGe
 =T0vB
 -----END PGP SIGNATURE-----

Merge tag 'kbuild-fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Search for <ncurses.h> in the default header path of HOSTCC

 - Tweak the option order to be kind to old BSD awk

 - Remove 'kvmconfig' and 'xenconfig' shorthands

 - Fix documentation

* tag 'kbuild-fixes-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  Documentation: kbuild: Fix section reference
  kconfig: remove 'kvmconfig' and 'xenconfig' shorthands
  lib/raid6: Let $(UNROLL) rules work with macOS userland
  kconfig: Support building mconf with vendor sysroot ncurses
  kconfig: config script: add a little user help
  MAINTAINERS: adjust GCC PLUGINS after gcc-plugin.sh removal
2021-01-10 13:24:55 -08:00
Linus Torvalds
688daed2e5 SCSI fixes on 20210110
This is two driver fixes (megaraid_sas and hisi_sas).  The megaraid
 one is a revert of a previous revert of a cpu hotplug fix which
 exposed a bug in the block layer which has been fixed in this merge
 window and the hisi_sas performance enhancement comes from switching
 to interrupt managed completion queues, which depended on the addition
 of devm_platform_get_irqs_affinity() which is now upstream via the irq
 tree in the last merge window.
 
 Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
 -----BEGIN PGP SIGNATURE-----
 
 iJwEABMIAEQWIQTnYEDbdso9F2cI+arnQslM7pishQUCX/tF/SYcamFtZXMuYm90
 dG9tbGV5QGhhbnNlbnBhcnRuZXJzaGlwLmNvbQAKCRDnQslM7pishTYGAQDzi9Zi
 iJ0uut1ex6io0q/X+DU7vwYFSfx9wILi8k8jFwD8C9O4pPfdvZyfPqLx/ol90lxW
 fEIZK6p7MozgoSw7s9k=
 =jp38
 -----END PGP SIGNATURE-----

Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi

Pull SCSI fixes from James Bottomley:
 "This is two driver fixes (megaraid_sas and hisi_sas).

  The megaraid one is a revert of a previous revert of a cpu hotplug fix
  which exposed a bug in the block layer which has been fixed in this
  merge window.

  The hisi_sas performance enhancement comes from switching to interrupt
  managed completion queues, which depended on the addition of
  devm_platform_get_irqs_affinity() which is now upstream via the irq
  tree in the last merge window"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: hisi_sas: Expose HW queues for v2 hw
  Revert "Revert "scsi: megaraid_sas: Added support for shared host tagset for cpuhotplug""
2021-01-10 13:17:21 -08:00