5.10-stable patches

added patches:
	x86-entry-emit-a-symbol-for-register-restoring-thunk.patch

diff --git a/queue-5.10/series b/queue-5.10/series
index ef5942c7b4c2d185d81814571791bd21b20a1089..4dd9a5de65a0db2a6aeb23067ccf2dbb6014db51 100644 (file)
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -29,3 +29,4 @@ net-usb-qmi_wwan-added-support-for-thales-cinterion-plsx3-modem-family.patch
 s390-uv-fix-sysfs-max-number-of-vcpus-reporting.patch
 s390-vfio-ap-no-need-to-disable-irq-after-queue-reset.patch
 pm-hibernate-flush-swap-writer-after-marking.patch
+x86-entry-emit-a-symbol-for-register-restoring-thunk.patch

diff --git a/queue-5.10/x86-entry-emit-a-symbol-for-register-restoring-thunk.patch b/queue-5.10/x86-entry-emit-a-symbol-for-register-restoring-thunk.patch
new file mode 100644 (file)
index 0000000..043d4a8
--- /dev/null
+++ b/queue-5.10/x86-entry-emit-a-symbol-for-register-restoring-thunk.patch
@@ -0,0 +1,123 @@
+From 5e6dca82bcaa49348f9e5fcb48df4881f6d6c4ae Mon Sep 17 00:00:00 2001
+From: Nick Desaulniers <ndesaulniers@google.com>
+Date: Tue, 12 Jan 2021 11:46:24 -0800
+Subject: x86/entry: Emit a symbol for register restoring thunk
+
+From: Nick Desaulniers <ndesaulniers@google.com>
+
+commit 5e6dca82bcaa49348f9e5fcb48df4881f6d6c4ae upstream.
+
+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]
+Cc: Chris Clayton <chris2553@googlemail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ Documentation/asm-annotations.rst |    5 +++++
+ arch/x86/entry/thunk_64.S         |    8 ++++----
+ include/linux/linkage.h           |    5 +++++
+ 3 files changed, 14 insertions(+), 4 deletions(-)
+
+--- a/Documentation/asm-annotations.rst
++++ b/Documentation/asm-annotations.rst
+@@ -100,6 +100,11 @@ Instruction Macros
+ ~~~~~~~~~~~~~~~~~~
+ This section covers ``SYM_FUNC_*`` and ``SYM_CODE_*`` enumerated above.
+ 
++``objtool`` requires that all code must be contained in an ELF symbol. Symbol
++names that have a ``.L`` prefix do not emit symbol table entries. ``.L``
++prefixed symbols can be used within a code region, but should be avoided for
++denoting a range of code via ``SYM_*_START/END`` annotations.
++
+ * ``SYM_FUNC_START`` and ``SYM_FUNC_START_LOCAL`` are supposed to be **the
+   most frequent markings**. They are used for functions with standard calling
+   conventions -- global and local. Like in C, they both align the functions to
+--- a/arch/x86/entry/thunk_64.S
++++ b/arch/x86/entry/thunk_64.S
+@@ -31,7 +31,7 @@ SYM_FUNC_START_NOALIGN(\name)
+       .endif
+ 
+       call \func
+-      jmp  .L_restore
++      jmp  __thunk_restore
+ SYM_FUNC_END(\name)
+       _ASM_NOKPROBE(\name)
+       .endm
+@@ -44,7 +44,7 @@ SYM_FUNC_END(\name)
+ #endif
+ 
+ #ifdef CONFIG_PREEMPTION
+-SYM_CODE_START_LOCAL_NOALIGN(.L_restore)
++SYM_CODE_START_LOCAL_NOALIGN(__thunk_restore)
+       popq %r11
+       popq %r10
+       popq %r9
+@@ -56,6 +56,6 @@ SYM_CODE_START_LOCAL_NOALIGN(.L_restore)
+       popq %rdi
+       popq %rbp
+       ret
+-      _ASM_NOKPROBE(.L_restore)
+-SYM_CODE_END(.L_restore)
++      _ASM_NOKPROBE(__thunk_restore)
++SYM_CODE_END(__thunk_restore)
+ #endif
+--- a/include/linux/linkage.h
++++ b/include/linux/linkage.h
+@@ -178,6 +178,11 @@
+  * Objtool generates debug info for both FUNC & CODE, but needs special
+  * annotations for each CODE's start (to describe the actual stack frame).
+  *
++ * Objtool requires that all code must be contained in an ELF symbol. Symbol
++ * names that have a  .L prefix do not emit symbol table entries. .L
++ * prefixed symbols can be used within a code region, but should be avoided for
++ * denoting a range of code via ``SYM_*_START/END`` annotations.
++ *
+  * ALIAS -- does not generate debug info -- the aliased function will
+  */
+