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x86/entry: Rename ignore_sysret()

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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@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230623111409.3047467-3-nik.borisov@suse.com
This commit is contained in:
Nikolay Borisov 2023-06-23 14:14:05 +03:00 • committed by Thomas Gleixner
parent 1da5c9bc11
commit f71e1d2ff8
3 changed files with 4 additions and 4 deletions
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4
arch/x86/entry/entry_64.S
View file

@ -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"

2
arch/x86/include/asm/processor.h
View file

@ -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);

2
arch/x86/kernel/cpu/common.c
View file

@ -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);