This is a note to let you know that I've just added the patch titled
x86/entry: Rename ignore_sysret()
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-entry-rename-ignore_sysret.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 4e3e44c814f8b51231553e96ba2600f27c27b254
Author: Nikolay Borisov <nik.borisov@xxxxxxxx>
Date: Fri Jun 23 14:14:05 2023 +0300
x86/entry: Rename ignore_sysret()
[ Upstream commit f71e1d2ff8e6a183bd4004bc97c453ba527b7dc6 ]
The SYSCALL instruction cannot really be disabled in compatibility mode.
The best that can be done is to configure the CSTAR msr to point to a
minimal handler. Currently this handler has a rather misleading name -
ignore_sysret() as it's not really doing anything with sysret.
Give it a more descriptive name.
Signed-off-by: Nikolay Borisov <nik.borisov@xxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230623111409.3047467-3-nik.borisov@xxxxxxxx
Stable-dep-of: ac8b270b61d4 ("x86/bhi: Avoid warning in #DB handler due to BHI mitigation")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 5d96561c0d6ad..1edb8e1b9e018 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1527,13 +1527,13 @@ SYM_CODE_END(asm_exc_nmi)
* This handles SYSCALL from 32-bit code. There is no way to program
* MSRs to fully disable 32-bit SYSCALL.
*/
-SYM_CODE_START(ignore_sysret)
+SYM_CODE_START(entry_SYSCALL32_ignore)
UNWIND_HINT_END_OF_STACK
ENDBR
mov $-ENOSYS, %eax
CLEAR_CPU_BUFFERS
sysretl
-SYM_CODE_END(ignore_sysret)
+SYM_CODE_END(entry_SYSCALL32_ignore)
#endif
.pushsection .text, "ax"
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 6e19d0f226000..67ad64efa9263 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -399,7 +399,7 @@ static inline unsigned long cpu_kernelmode_gs_base(int cpu)
return (unsigned long)per_cpu(fixed_percpu_data.gs_base, cpu);
}
-extern asmlinkage void ignore_sysret(void);
+extern asmlinkage void entry_SYSCALL32_ignore(void);
/* Save actual FS/GS selectors and bases to current->thread */
void current_save_fsgs(void);
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 340dd6cc11af4..74d566263467e 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2134,7 +2134,7 @@ void syscall_init(void)
(unsigned long)(cpu_entry_stack(smp_processor_id()) + 1));
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
#else
- wrmsrl_cstar((unsigned long)ignore_sysret);
+ wrmsrl_cstar((unsigned long)entry_SYSCALL32_ignore);
wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)GDT_ENTRY_INVALID_SEG);
wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
wrmsrl_safe(MSR_IA32_SYSENTER_EIP, 0ULL);
