Commit 207ddb91 authored by Heiko Carstens's avatar Heiko Carstens Committed by Alexander Gordeev
Browse files

s390/alternatives: Convert runtime sanity check into compile time check 



__apply_alternatives() contains a runtime check which verifies that the
size of the to be patched code area is even. Convert this to a compile time
check using a similar ".org" trick, which is already used to verify that
old and new code areas have the same size.

Reviewed-by: default avatarSven Schnelle <svens@linux.ibm.com>
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Signed-off-by: default avatarAlexander Gordeev <agordeev@linux.ibm.com>
parent effb8357

arch/s390/include/asm/alternative-asm.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ 
	.long	\alt_start - .

	.word	\feature

	.byte	\orig_end - \orig_start

	.org	. - ( \orig_end - \orig_start ) & 1

	.org	. - ( \orig_end - \orig_start ) + ( \alt_end - \alt_start )

	.org	. - ( \alt_end - \alt_start ) + ( \orig_end - \orig_start )

.endm

arch/s390/include/asm/alternative.h

+1 −0
Original line number Diff line number Diff line
@@ -53,6 +53,7 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end); 
	"\t.long " b_altinstr(num)"b - .\n"	/* alt instruction */	\

	"\t.word " __stringify(facility) "\n"	/* facility bit    */	\

	"\t.byte " oldinstr_len "\n"		/* instruction len */	\

	"\t.org . - (" oldinstr_len ") & 1\n"				\

	"\t.org . - (" oldinstr_len ") + (" altinstr_len(num) ")\n"	\

	"\t.org . - (" altinstr_len(num) ") + (" oldinstr_len ")\n"

arch/s390/kernel/alternative.c

+0 −7
Original line number Diff line number Diff line
@@ -33,13 +33,6 @@ static void __init_or_module __apply_alternatives(struct alt_instr *start, 


		if (!__test_facility(a->facility, alt_stfle_fac_list))

			continue;



		if (unlikely(a->instrlen % 2)) {

			WARN_ONCE(1, "cpu alternatives instructions length is "

				     "odd, skipping patching\n");

			continue;

		}



		s390_kernel_write(instr, replacement, a->instrlen);

	}

}