Commit 7f6c5b04 authored by Andi Kleen's avatar Andi Kleen Committed by Linus Torvalds
Browse files

[PATCH] x86_64: Support alternative() in vsyscalls 



The real vsyscall .text addresses are not mapped when the alternative()
replacement runs early, so use some black magic to access them using
the direct mapping.

Signed-off-by: default avatarAndi Kleen <ak@suse.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 6e54d95f

arch/x86_64/kernel/setup.c

+10 −2
Original line number Diff line number Diff line
@@ -478,6 +478,8 @@ static unsigned char *k8_nops[ASM_NOP_MAX+1] = { 
     k8nops + 1 + 2 + 3 + 4 + 5 + 6 + 7,

}; 



extern char __vsyscall_0;



/* Replace instructions with better alternatives for this CPU type.



   This runs before SMP is initialized to avoid SMP problems with
@@ -489,11 +491,17 @@ void apply_alternatives(void *start, void *end) 
	struct alt_instr *a; 

	int diff, i, k;

	for (a = start; (void *)a < end; a++) { 

		u8 *instr;



		if (!boot_cpu_has(a->cpuid))

			continue;



		BUG_ON(a->replacementlen > a->instrlen); 

		__inline_memcpy(a->instr, a->replacement, a->replacementlen); 

		instr = a->instr;

		/* vsyscall code is not mapped yet. resolve it manually. */

		if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END)

			instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));

		__inline_memcpy(instr, a->replacement, a->replacementlen);

		diff = a->instrlen - a->replacementlen; 



		/* Pad the rest with nops */
@@ -501,7 +509,7 @@ void apply_alternatives(void *start, void *end) 
			k = diff;

			if (k > ASM_NOP_MAX)

				k = ASM_NOP_MAX;

			__inline_memcpy(a->instr + i, k8_nops[k], k); 

			__inline_memcpy(instr + i, k8_nops[k], k);

		} 

	}

}