Re: [PATCH 6.6.y] x86/stackprotector: Work around strict Clang TLS symbol requirements

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Found matching upstream commit: 577c134d311b9b94598d7a0c86be1f431f823003

WARNING: Author mismatch between patch and found commit:
Backport author: Brian Gerst <brgerst@gmail.com>
Commit author: Ard Biesheuvel <ardb@kernel.org>


Status in newer kernel trees:
6.12.y | Present (exact SHA1)
6.11.y | Present (different SHA1: 43d5fb3ac23e)
6.6.y | Not found

Note: The patch differs from the upstream commit:
---
--- -	2024-11-21 11:32:21.903231818 -0500
+++ /tmp/tmp.Q0DbBn1V8Q	2024-11-21 11:32:21.894493156 -0500
@@ -38,40 +38,37 @@
 Cc: stable@vger.kernel.org
 Link: https://github.com/ClangBuiltLinux/linux/issues/1854
 Link: https://lore.kernel.org/r/20241105155801.1779119-2-brgerst@gmail.com
+(cherry picked from commit 577c134d311b9b94598d7a0c86be1f431f823003)
 ---
- arch/x86/Makefile                     |  5 +++--
- arch/x86/entry/entry.S                | 16 ++++++++++++++++
+ arch/x86/Makefile                     |  3 ++-
+ arch/x86/entry/entry.S                | 15 +++++++++++++++
  arch/x86/include/asm/asm-prototypes.h |  3 +++
  arch/x86/kernel/cpu/common.c          |  2 ++
  arch/x86/kernel/vmlinux.lds.S         |  3 +++
- 5 files changed, 27 insertions(+), 2 deletions(-)
+ 5 files changed, 25 insertions(+), 1 deletion(-)
 
 diff --git a/arch/x86/Makefile b/arch/x86/Makefile
-index cd75e78a06c10..5b773b34768d1 100644
+index 3ff53a2d4ff0..c83582b5a010 100644
 --- a/arch/x86/Makefile
 +++ b/arch/x86/Makefile
-@@ -142,9 +142,10 @@ ifeq ($(CONFIG_X86_32),y)
+@@ -113,7 +113,8 @@ ifeq ($(CONFIG_X86_32),y)
  
-     ifeq ($(CONFIG_STACKPROTECTOR),y)
-         ifeq ($(CONFIG_SMP),y)
+ 	ifeq ($(CONFIG_STACKPROTECTOR),y)
+ 		ifeq ($(CONFIG_SMP),y)
 -			KBUILD_CFLAGS += -mstack-protector-guard-reg=fs -mstack-protector-guard-symbol=__stack_chk_guard
-+            KBUILD_CFLAGS += -mstack-protector-guard-reg=fs \
-+                             -mstack-protector-guard-symbol=__ref_stack_chk_guard
-         else
--			KBUILD_CFLAGS += -mstack-protector-guard=global
-+            KBUILD_CFLAGS += -mstack-protector-guard=global
-         endif
-     endif
- else
++			KBUILD_CFLAGS += -mstack-protector-guard-reg=fs \
++					 -mstack-protector-guard-symbol=__ref_stack_chk_guard
+ 		else
+ 			KBUILD_CFLAGS += -mstack-protector-guard=global
+ 		endif
 diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
-index 324686bca3681..b7ea3e8e9eccd 100644
+index 34eca8015b64..2143358d0c4c 100644
 --- a/arch/x86/entry/entry.S
 +++ b/arch/x86/entry/entry.S
-@@ -51,3 +51,19 @@ EXPORT_SYMBOL_GPL(mds_verw_sel);
+@@ -48,3 +48,18 @@ EXPORT_SYMBOL_GPL(mds_verw_sel);
+ 
  .popsection
  
- THUNK warn_thunk_thunk, __warn_thunk
-+
 +#ifndef CONFIG_X86_64
 +/*
 + * Clang's implementation of TLS stack cookies requires the variable in
@@ -88,10 +85,10 @@
 +#endif
 +#endif
 diff --git a/arch/x86/include/asm/asm-prototypes.h b/arch/x86/include/asm/asm-prototypes.h
-index 25466c4d21348..3674006e39744 100644
+index 0e82074517f6..768076e68668 100644
 --- a/arch/x86/include/asm/asm-prototypes.h
 +++ b/arch/x86/include/asm/asm-prototypes.h
-@@ -20,3 +20,6 @@
+@@ -19,3 +19,6 @@
  extern void cmpxchg8b_emu(void);
  #endif
  
@@ -99,10 +96,10 @@
 +extern unsigned long __ref_stack_chk_guard;
 +#endif
 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
-index a5f221ea56888..f43bb974fc66d 100644
+index 7a1e58fb43a0..852cc2ab4df9 100644
 --- a/arch/x86/kernel/cpu/common.c
 +++ b/arch/x86/kernel/cpu/common.c
-@@ -2089,8 +2089,10 @@ void syscall_init(void)
+@@ -2159,8 +2159,10 @@ void syscall_init(void)
  
  #ifdef CONFIG_STACKPROTECTOR
  DEFINE_PER_CPU(unsigned long, __stack_chk_guard);
@@ -114,16 +111,21 @@
  #endif	/* CONFIG_X86_64 */
  
 diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
-index b8c5741d2fb48..feb8102a9ca78 100644
+index 54a5596adaa6..60eb8baa44d7 100644
 --- a/arch/x86/kernel/vmlinux.lds.S
 +++ b/arch/x86/kernel/vmlinux.lds.S
-@@ -491,6 +491,9 @@ SECTIONS
- . = ASSERT((_end - LOAD_OFFSET <= KERNEL_IMAGE_SIZE),
- 	   "kernel image bigger than KERNEL_IMAGE_SIZE");
+@@ -496,6 +496,9 @@ SECTIONS
+ 	ASSERT(SIZEOF(.rela.dyn) == 0, "Unexpected run-time relocations (.rela) detected!")
+ }
  
 +/* needed for Clang - see arch/x86/entry/entry.S */
 +PROVIDE(__ref_stack_chk_guard = __stack_chk_guard);
 +
- #ifdef CONFIG_X86_64
  /*
-  * Per-cpu symbols which need to be offset from __per_cpu_load
+  * The ASSERT() sink to . is intentional, for binutils 2.14 compatibility:
+  */
+
+base-commit: c1036e4f14d03aba549cdd9b186148d331013056
+-- 
+2.47.0
+
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.6.y        |  Success    |  Success   |