linux-toradex.git/arch/x86/entry, branch v5.18

x86,objtool: Explicitly mark idtentry_body()s tail REACHABLE

2022-04-19T19:58:48+00:00

Objtool can figure out that some \cfunc()s are noreturn and then
complains about certain instances having unreachable tails:

  vmlinux.o: warning: objtool: asm_exc_xen_unknown_trap()+0x16: unreachable instruction

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220408094718.441854969@infradead.org

Merge tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2022-03-31T18:59:03+00:00

Pull Kbuild updates from Masahiro Yamada:

 - Add new environment variables, USERCFLAGS and USERLDFLAGS to allow
   additional flags to be passed to user-space programs.

 - Fix missing fflush() bugs in Kconfig and fixdep

 - Fix a minor bug in the comment format of the .config file

 - Make kallsyms ignore llvm's local labels, .L*

 - Fix UAPI compile-test for cross-compiling with Clang

 - Extend the LLVM= syntax to support LLVM= form for using a
   particular version of LLVm, and LLVM= form for using custom
   LLVM in a particular directory path.

 - Clean up Makefiles

* tag 'kbuild-v5.18-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: Make $(LLVM) more flexible
  kbuild: add --target to correctly cross-compile UAPI headers with Clang
  fixdep: use fflush() and ferror() to ensure successful write to files
  arch: syscalls: simplify uapi/kapi directory creation
  usr/include: replace extra-y with always-y
  certs: simplify empty certs creation in certs/Makefile
  certs: include certs/signing_key.x509 unconditionally
  kallsyms: ignore all local labels prefixed by '.L'
  kconfig: fix missing '# end of' for empty menu
  kconfig: add fflush() before ferror() check
  kbuild: replace $(if A,A,B) with $(or A,B)
  kbuild: Add environment variables for userprogs flags
  kbuild: unify cmd_copy and cmd_shipped

arch: syscalls: simplify uapi/kapi directory creation

2022-03-31T03:03:46+00:00

$(shell ...) expands to empty. There is no need to assign it to _dummy.

Signed-off-by: Masahiro Yamada 
Acked-by: Geert Uytterhoeven

x86: Remove toolchain check for X32 ABI capability

2022-03-15T09:32:48+00:00

Commit 0bf6276392e9 ("x32: Warn and disable rather than error if
binutils too old") added a small test in arch/x86/Makefile because
binutils 2.22 or newer is needed to properly support elf32-x86-64. This
check is no longer necessary, as the minimum supported version of
binutils is 2.23, which is enforced at configuration time with
scripts/min-tool-version.sh.

Remove this check and replace all uses of CONFIG_X86_X32 with
CONFIG_X86_X32_ABI, as two symbols are no longer necessary.

[nathan: Rebase, fix up a few places where CONFIG_X86_X32 was still
         used, and simplify commit message to satisfy -tip requirements]

Signed-off-by: Masahiro Yamada 
Signed-off-by: Nathan Chancellor 
Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lore.kernel.org/r/20220314194842.3452-2-nathan@kernel.org

x86: Annotate idtentry_df()

2022-03-15T09:32:45+00:00

Without CONFIG_X86_ESPFIX64 exc_double_fault() is noreturn and objtool
is clever enough to figure that out.

vmlinux.o: warning: objtool: asm_exc_double_fault()+0x22: unreachable instruction

0000000000001260 :
1260:       f3 0f 1e fa             endbr64
1264:       90                      nop
1265:       90                      nop
1266:       90                      nop
1267:       e8 84 03 00 00          call   15f0 
126c:       48 89 e7                mov    %rsp,%rdi
126f:       48 8b 74 24 78          mov    0x78(%rsp),%rsi
1274:       48 c7 44 24 78 ff ff ff ff      movq   $0xffffffffffffffff,0x78(%rsp)
127d:       e8 00 00 00 00          call   1282  127e: R_X86_64_PLT32    exc_double_fault-0x4
1282:       e9 09 04 00 00          jmp    1690 

Signed-off-by: Peter Zijlstra (Intel) 
Link: https://lkml.kernel.org/r/Yi9gOW9f1GGwwUD6@hirez.programming.kicks-ass.net

x86/ibt,sev: Annotations

2022-03-15T09:32:41+00:00

No IBT on AMD so far.. probably correct, who knows.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154318.995109889@infradead.org

x86/ibt: Annotate text references

2022-03-15T09:32:40+00:00

Annotate away some of the generic code references. This is things
where we take the address of a symbol for exception handling or return
addresses (eg. context switch).

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154318.877758523@infradead.org

x86/ibt,entry: Sprinkle ENDBR dust

2022-03-15T09:32:35+00:00

Kernel entry points should be having ENDBR on for IBT configs.

The SYSCALL entry points are found through taking their respective
address in order to program them in the MSRs, while the exception
entry points are found through UNWIND_HINT_IRET_REGS.

The rule is that any UNWIND_HINT_IRET_REGS at sym+0 should have an
ENDBR, see the later objtool ibt validation patch.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154317.933157479@infradead.org

x86/ibt,xen: Sprinkle the ENDBR

2022-03-15T09:32:35+00:00

Even though Xen currently doesn't advertise IBT, prepare for when it
will eventually do so and sprinkle the ENDBR dust accordingly.

Even though most of the entry points are IRET like, the CPL0
Hypervisor can set WAIT-FOR-ENDBR and demand ENDBR at these sites.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154317.873919996@infradead.org

x86/entry,xen: Early rewrite of restore_regs_and_return_to_kernel()

2022-03-15T09:32:34+00:00

By doing an early rewrite of 'jmp native_iret` in
restore_regs_and_return_to_kernel() we can get rid of the last
INTERRUPT_RETURN user and paravirt_iret.

Suggested-by: Andrew Cooper 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Josh Poimboeuf 
Link: https://lore.kernel.org/r/20220308154317.815039833@infradead.org