Commit 3c6cbc57 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Jialin Zhang
Browse files

x86/alternative: Make custom return thunk unconditional 

stable inclusion
from stable-v5.10.192
commit bd3d12e6fda0a7911a0f56f223924bb075b92d1e
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7RQ67

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bd3d12e6fda0a7911a0f56f223924bb075b92d1e



--------------------------------

commit 095b8303 upstream.

There is infrastructure to rewrite return thunks to point to any
random thunk one desires, unwrap that from CALL_THUNKS, which up to
now was the sole user of that.

  [ bp: Make the thunks visible on 32-bit and add ifdeffery for the
    32-bit builds. ]

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230814121148.775293785@infradead.org


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJialin Zhang <zhangjialin11@huawei.com>
parent cda9fda6

arch/x86/include/asm/nospec-branch.h

+5 −0
Original line number Diff line number Diff line
@@ -195,7 +195,12 @@ 
	_ASM_PTR " 999b\n\t"					\

	".popsection\n\t"



#ifdef CONFIG_RETHUNK

extern void __x86_return_thunk(void);

#else

static inline void __x86_return_thunk(void) {}

#endif



extern void zen_untrain_ret(void);

extern void srso_untrain_ret(void);

extern void srso_untrain_ret_alias(void);

arch/x86/kernel/cpu/bugs.c

+2 −0
Original line number Diff line number Diff line
@@ -64,6 +64,8 @@ EXPORT_SYMBOL_GPL(x86_pred_cmd); 


static DEFINE_MUTEX(spec_ctrl_mutex);



void (*x86_return_thunk)(void) __ro_after_init = &__x86_return_thunk;



/* Update SPEC_CTRL MSR and its cached copy unconditionally */

static void update_spec_ctrl(u64 val)

{