x86/entry: Make IA32 syscalls' availability depend on ia32_enabled()

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Another major aspect of supporting running of 32bit processes is the
ability to access 32bit syscalls. Such syscalls can be invoked by
using the legacy int 0x80 handler and  sysenter/syscall instructions.

If IA32 emulation is disabled ensure that each of those 3 distinct
mechanisms are also disabled. For int 0x80 a #GP exception would be
generated since the respective descriptor is not going to be loaded at
all. Invoking sysenter will also result in a #GP since IA32_SYSENTER_CS
contains an invalid segment. Finally, syscall instruction cannot really
be disabled so it's configured to execute a minimal handler.

Signed-off-by: Nikolay Borisov <nik.borisov@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230623111409.3047467-6-nik.borisov@suse.com

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Nikolay Borisov 2023-06-23 14:14:08 +03:00 • committed by Thomas Gleixner

parent 5ae2702d7c

commit 61382281e9

3 changed files with 29 additions and 18 deletions

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3

arch/x86/include/asm/proto.h

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37

arch/x86/kernel/cpu/common.c

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7

arch/x86/kernel/idt.c

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