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The stfle() function writes into lowcore memory when stfl_fac_list is initialized with "S390_lowcore.stfl_fac_list = 0". For older compilers this triggers a lowcore exception. With newer compilers and "-OXX" compile option the bug does not show up because the "S390_lowcore.stfl_fac_list" initialization is removed by the compiler. The reason for thatis the incorrect "=m" (S390_lowcore.stfl_fac_list) constraint in the stfl inline assembly. The following shows the disassembly of the stfle() optimized code that is inlined in the lgr_info_get() function: 000000000011325c <lgr_info_get>: 11325c: eb 9f f0 60 00 24 stmg %r9,%r15,96(%r15) 113262: c0 d0 00 29 0e 47 larl %r13,634ef0 <servi..> 113268: a7 f1 3f c0 tml %r15,16320 11326c: b9 04 00 ef lgr %r14,%r15 113270: a7 84 00 01 je 113272 <lgr_info_g..> 113274: a7 fb ff c0 aghi %r15,-64 113278: b9 04 00 c2 lgr %r12,%r2 11327c: a7 29 00 01 lghi %r2,1 113280: e3 e0 f0 98 00 24 stg %r14,152(%r15) 113286: d7 97 c0 00 c0 00 xc 0(152,%r12),0(%r12) 11328c: c0 e5 00 28 db 4c brasl %r14,62e924 <add_e..> 113292: b2 b1 00 00 stfl 0 To fix the problem we now clear the S390_lowcore.stfl_fac_list at startup in "head.S" for all machine types before lowcore protection is enabled. In addition to that the "=m" constraint is replaced by "+m". Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
62 lines
1.6 KiB
C
62 lines
1.6 KiB
C
/*
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* Copyright IBM Corp. 1999, 2009
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*
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* Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
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*/
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#ifndef __ASM_FACILITY_H
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#define __ASM_FACILITY_H
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#include <linux/string.h>
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#include <linux/preempt.h>
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#include <asm/lowcore.h>
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#define MAX_FACILITY_BIT (256*8) /* stfle_fac_list has 256 bytes */
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/*
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* The test_facility function uses the bit odering where the MSB is bit 0.
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* That makes it easier to query facility bits with the bit number as
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* documented in the Principles of Operation.
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*/
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static inline int test_facility(unsigned long nr)
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{
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unsigned char *ptr;
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if (nr >= MAX_FACILITY_BIT)
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return 0;
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ptr = (unsigned char *) &S390_lowcore.stfle_fac_list + (nr >> 3);
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return (*ptr & (0x80 >> (nr & 7))) != 0;
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}
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/**
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* stfle - Store facility list extended
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* @stfle_fac_list: array where facility list can be stored
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* @size: size of passed in array in double words
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*/
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static inline void stfle(u64 *stfle_fac_list, int size)
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{
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unsigned long nr;
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preempt_disable();
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asm volatile(
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" .insn s,0xb2b10000,0(0)\n" /* stfl */
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"0:\n"
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EX_TABLE(0b, 0b)
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: "+m" (S390_lowcore.stfl_fac_list));
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nr = 4; /* bytes stored by stfl */
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memcpy(stfle_fac_list, &S390_lowcore.stfl_fac_list, 4);
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if (S390_lowcore.stfl_fac_list & 0x01000000) {
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/* More facility bits available with stfle */
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register unsigned long reg0 asm("0") = size - 1;
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asm volatile(".insn s,0xb2b00000,0(%1)" /* stfle */
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: "+d" (reg0)
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: "a" (stfle_fac_list)
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: "memory", "cc");
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nr = (reg0 + 1) * 8; /* # bytes stored by stfle */
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}
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memset((char *) stfle_fac_list + nr, 0, size * 8 - nr);
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preempt_enable();
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}
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#endif /* __ASM_FACILITY_H */
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