[tip: x86/entry] x86/entry: Rename ignore_sysret()

[tip-bot2 for Nikolay Borisov]

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     f71e1d2ff8e6a183bd4004bc97c453ba527b7dc6
Gitweb:        https://git.kernel.org/tip/f71e1d2ff8e6a183bd4004bc97c453ba527b7dc6
Author:        Nikolay Borisov <nik.borisov@xxxxxxxx>
AuthorDate:    Fri, 23 Jun 2023 14:14:05 +03:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 14 Sep 2023 13:19:53 +02:00

x86/entry: Rename ignore_sysret()

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

---
 arch/x86/entry/entry_64.S        | 4 ++--
 arch/x86/include/asm/processor.h | 2 +-
 arch/x86/kernel/cpu/common.c     | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 43606de..3be71ac 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1516,12 +1516,12 @@ 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
 	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 0086920..93cd28d 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 382d4e6..b3f8cba 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -2087,7 +2087,7 @@ 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);