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x86/asm: Remove CR4 read fault handler

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Remove the fault handler from native_read_cr4() since 486 support has
been removed.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20260905225519.1002976-1-brgerst@gmail.com
This commit is contained in:
Brian Gerst 2026-09-05 18:55:19 -04:00 committed by Borislav Petkov (AMD)
parent 2c6a75adb1
commit 27441d76b3
1 changed files with 0 additions and 13 deletions
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13
arch/x86/include/asm/special_insns.h
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@ -46,20 +46,7 @@ static __always_inline void native_write_cr3(unsigned long val)
static inline unsigned long native_read_cr4(void)
{
unsigned long val;
#ifdef CONFIG_X86_32
/*
* This could fault if CR4 does not exist. Non-existent CR4
* is functionally equivalent to CR4 == 0. Keep it simple and pretend
* that CR4 == 0 on CPUs that don't have CR4.
*/
asm volatile("1: mov %%cr4, %0\n"
"2:\n"
_ASM_EXTABLE(1b, 2b)
: "=r" (val) : "0" (0));
#else
/* CR4 always exists on x86_64. */
asm volatile("mov %%cr4,%0" : "=r" (val));
#endif
return val;
}