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Merge branch 'cmpxchg_user_key' into features
Signed-off-by: Heiko Carstens <[email protected]>
2 parents 20e6ce4 + b33d59f commit 740d63b

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4 files changed

+285
-45
lines changed

4 files changed

+285
-45
lines changed

‎arch/s390/include/asm/asm-extable.h‎

Lines changed: 4 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -12,6 +12,7 @@
1212
#define EX_TYPE_UA_STORE 3
1313
#define EX_TYPE_UA_LOAD_MEM 4
1414
#define EX_TYPE_UA_LOAD_REG 5
15+
#define EX_TYPE_UA_LOAD_REGPAIR 6
1516

1617
#define EX_DATA_REG_ERR_SHIFT 0
1718
#define EX_DATA_REG_ERR GENMASK(3, 0)
@@ -85,4 +86,7 @@
8586
#define EX_TABLE_UA_LOAD_REG(_fault, _target, _regerr, _regzero) \
8687
__EX_TABLE_UA(__ex_table, _fault, _target, EX_TYPE_UA_LOAD_REG, _regerr, _regzero, 0)
8788

89+
#define EX_TABLE_UA_LOAD_REGPAIR(_fault, _target, _regerr, _regzero) \
90+
__EX_TABLE_UA(__ex_table, _fault, _target, EX_TYPE_UA_LOAD_REGPAIR, _regerr, _regzero, 0)
91+
8892
#endif /* __ASM_EXTABLE_H */

‎arch/s390/include/asm/cmpxchg.h‎

Lines changed: 66 additions & 43 deletions
Original file line numberDiff line numberDiff line change
@@ -88,67 +88,90 @@ static __always_inline unsigned long __cmpxchg(unsigned long address,
8888
unsigned long old,
8989
unsigned long new, int size)
9090
{
91-
unsigned long prev, tmp;
92-
int shift;
93-
9491
switch (size) {
95-
case 1:
92+
case 1: {
93+
unsigned int prev, shift, mask;
94+
9695
shift = (3 ^ (address & 3)) << 3;
9796
address ^= address & 3;
97+
old = (old & 0xff) << shift;
98+
new = (new & 0xff) << shift;
99+
mask = ~(0xff << shift);
98100
asm volatile(
99-
" l %0,%2\n"
100-
"0: nr %0,%5\n"
101-
" lr %1,%0\n"
102-
" or %0,%3\n"
103-
" or %1,%4\n"
104-
" cs %0,%1,%2\n"
105-
" jnl 1f\n"
106-
" xr %1,%0\n"
107-
" nr %1,%5\n"
108-
" jnz 0b\n"
101+
" l %[prev],%[address]\n"
102+
" nr %[prev],%[mask]\n"
103+
" xilf %[mask],0xffffffff\n"
104+
" or %[new],%[prev]\n"
105+
" or %[prev],%[tmp]\n"
106+
"0: lr %[tmp],%[prev]\n"
107+
" cs %[prev],%[new],%[address]\n"
108+
" jnl 1f\n"
109+
" xr %[tmp],%[prev]\n"
110+
" xr %[new],%[tmp]\n"
111+
" nr %[tmp],%[mask]\n"
112+
" jz 0b\n"
109113
"1:"
110-
: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
111-
: "d" ((old & 0xff) << shift),
112-
"d" ((new & 0xff) << shift),
113-
"d" (~(0xff << shift))
114-
: "memory", "cc");
114+
: [prev] "=&d" (prev),
115+
[address] "+Q" (*(int *)address),
116+
[tmp] "+&d" (old),
117+
[new] "+&d" (new),
118+
[mask] "+&d" (mask)
119+
:: "memory", "cc");
115120
return prev >> shift;
116-
case 2:
121+
}
122+
case 2: {
123+
unsigned int prev, shift, mask;
124+
117125
shift = (2 ^ (address & 2)) << 3;
118126
address ^= address & 2;
127+
old = (old & 0xffff) << shift;
128+
new = (new & 0xffff) << shift;
129+
mask = ~(0xffff << shift);
119130
asm volatile(
120-
" l %0,%2\n"
121-
"0: nr %0,%5\n"
122-
" lr %1,%0\n"
123-
" or %0,%3\n"
124-
" or %1,%4\n"
125-
" cs %0,%1,%2\n"
126-
" jnl 1f\n"
127-
" xr %1,%0\n"
128-
" nr %1,%5\n"
129-
" jnz 0b\n"
131+
" l %[prev],%[address]\n"
132+
" nr %[prev],%[mask]\n"
133+
" xilf %[mask],0xffffffff\n"
134+
" or %[new],%[prev]\n"
135+
" or %[prev],%[tmp]\n"
136+
"0: lr %[tmp],%[prev]\n"
137+
" cs %[prev],%[new],%[address]\n"
138+
" jnl 1f\n"
139+
" xr %[tmp],%[prev]\n"
140+
" xr %[new],%[tmp]\n"
141+
" nr %[tmp],%[mask]\n"
142+
" jz 0b\n"
130143
"1:"
131-
: "=&d" (prev), "=&d" (tmp), "+Q" (*(int *) address)
132-
: "d" ((old & 0xffff) << shift),
133-
"d" ((new & 0xffff) << shift),
134-
"d" (~(0xffff << shift))
135-
: "memory", "cc");
144+
: [prev] "=&d" (prev),
145+
[address] "+Q" (*(int *)address),
146+
[tmp] "+&d" (old),
147+
[new] "+&d" (new),
148+
[mask] "+&d" (mask)
149+
:: "memory", "cc");
136150
return prev >> shift;
137-
case 4:
151+
}
152+
case 4: {
153+
unsigned int prev = old;
154+
138155
asm volatile(
139-
" cs %0,%3,%1\n"
140-
: "=&d" (prev), "+Q" (*(int *) address)
141-
: "0" (old), "d" (new)
156+
" cs %[prev],%[new],%[address]\n"
157+
: [prev] "+&d" (prev),
158+
[address] "+Q" (*(int *)address)
159+
: [new] "d" (new)
142160
: "memory", "cc");
143161
return prev;
144-
case 8:
162+
}
163+
case 8: {
164+
unsigned long prev = old;
165+
145166
asm volatile(
146-
" csg %0,%3,%1\n"
147-
: "=&d" (prev), "+QS" (*(long *) address)
148-
: "0" (old), "d" (new)
167+
" csg %[prev],%[new],%[address]\n"
168+
: [prev] "+&d" (prev),
169+
[address] "+QS" (*(long *)address)
170+
: [new] "d" (new)
149171
: "memory", "cc");
150172
return prev;
151173
}
174+
}
152175
__cmpxchg_called_with_bad_pointer();
153176
return old;
154177
}

‎arch/s390/include/asm/uaccess.h‎

Lines changed: 208 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -390,4 +390,212 @@ do { \
390390
goto err_label; \
391391
} while (0)
392392

393+
void __cmpxchg_user_key_called_with_bad_pointer(void);
394+
395+
#define CMPXCHG_USER_KEY_MAX_LOOPS 128
396+
397+
static __always_inline int __cmpxchg_user_key(unsigned long address, void *uval,
398+
__uint128_t old, __uint128_t new,
399+
unsigned long key, int size)
400+
{
401+
int rc = 0;
402+
403+
switch (size) {
404+
case 1: {
405+
unsigned int prev, shift, mask, _old, _new;
406+
unsigned long count;
407+
408+
shift = (3 ^ (address & 3)) << 3;
409+
address ^= address & 3;
410+
_old = ((unsigned int)old & 0xff) << shift;
411+
_new = ((unsigned int)new & 0xff) << shift;
412+
mask = ~(0xff << shift);
413+
asm volatile(
414+
" spka 0(%[key])\n"
415+
" sacf 256\n"
416+
" llill %[count],%[max_loops]\n"
417+
"0: l %[prev],%[address]\n"
418+
"1: nr %[prev],%[mask]\n"
419+
" xilf %[mask],0xffffffff\n"
420+
" or %[new],%[prev]\n"
421+
" or %[prev],%[tmp]\n"
422+
"2: lr %[tmp],%[prev]\n"
423+
"3: cs %[prev],%[new],%[address]\n"
424+
"4: jnl 5f\n"
425+
" xr %[tmp],%[prev]\n"
426+
" xr %[new],%[tmp]\n"
427+
" nr %[tmp],%[mask]\n"
428+
" jnz 5f\n"
429+
" brct %[count],2b\n"
430+
"5: sacf 768\n"
431+
" spka %[default_key]\n"
432+
EX_TABLE_UA_LOAD_REG(0b, 5b, %[rc], %[prev])
433+
EX_TABLE_UA_LOAD_REG(1b, 5b, %[rc], %[prev])
434+
EX_TABLE_UA_LOAD_REG(3b, 5b, %[rc], %[prev])
435+
EX_TABLE_UA_LOAD_REG(4b, 5b, %[rc], %[prev])
436+
: [rc] "+&d" (rc),
437+
[prev] "=&d" (prev),
438+
[address] "+Q" (*(int *)address),
439+
[tmp] "+&d" (_old),
440+
[new] "+&d" (_new),
441+
[mask] "+&d" (mask),
442+
[count] "=a" (count)
443+
: [key] "%[count]" (key << 4),
444+
[default_key] "J" (PAGE_DEFAULT_KEY),
445+
[max_loops] "J" (CMPXCHG_USER_KEY_MAX_LOOPS)
446+
: "memory", "cc");
447+
*(unsigned char *)uval = prev >> shift;
448+
if (!count)
449+
rc = -EAGAIN;
450+
return rc;
451+
}
452+
case 2: {
453+
unsigned int prev, shift, mask, _old, _new;
454+
unsigned long count;
455+
456+
shift = (2 ^ (address & 2)) << 3;
457+
address ^= address & 2;
458+
_old = ((unsigned int)old & 0xffff) << shift;
459+
_new = ((unsigned int)new & 0xffff) << shift;
460+
mask = ~(0xffff << shift);
461+
asm volatile(
462+
" spka 0(%[key])\n"
463+
" sacf 256\n"
464+
" llill %[count],%[max_loops]\n"
465+
"0: l %[prev],%[address]\n"
466+
"1: nr %[prev],%[mask]\n"
467+
" xilf %[mask],0xffffffff\n"
468+
" or %[new],%[prev]\n"
469+
" or %[prev],%[tmp]\n"
470+
"2: lr %[tmp],%[prev]\n"
471+
"3: cs %[prev],%[new],%[address]\n"
472+
"4: jnl 5f\n"
473+
" xr %[tmp],%[prev]\n"
474+
" xr %[new],%[tmp]\n"
475+
" nr %[tmp],%[mask]\n"
476+
" jnz 5f\n"
477+
" brct %[count],2b\n"
478+
"5: sacf 768\n"
479+
" spka %[default_key]\n"
480+
EX_TABLE_UA_LOAD_REG(0b, 5b, %[rc], %[prev])
481+
EX_TABLE_UA_LOAD_REG(1b, 5b, %[rc], %[prev])
482+
EX_TABLE_UA_LOAD_REG(3b, 5b, %[rc], %[prev])
483+
EX_TABLE_UA_LOAD_REG(4b, 5b, %[rc], %[prev])
484+
: [rc] "+&d" (rc),
485+
[prev] "=&d" (prev),
486+
[address] "+Q" (*(int *)address),
487+
[tmp] "+&d" (_old),
488+
[new] "+&d" (_new),
489+
[mask] "+&d" (mask),
490+
[count] "=a" (count)
491+
: [key] "%[count]" (key << 4),
492+
[default_key] "J" (PAGE_DEFAULT_KEY),
493+
[max_loops] "J" (CMPXCHG_USER_KEY_MAX_LOOPS)
494+
: "memory", "cc");
495+
*(unsigned short *)uval = prev >> shift;
496+
if (!count)
497+
rc = -EAGAIN;
498+
return rc;
499+
}
500+
case 4: {
501+
unsigned int prev = old;
502+
503+
asm volatile(
504+
" spka 0(%[key])\n"
505+
" sacf 256\n"
506+
"0: cs %[prev],%[new],%[address]\n"
507+
"1: sacf 768\n"
508+
" spka %[default_key]\n"
509+
EX_TABLE_UA_LOAD_REG(0b, 1b, %[rc], %[prev])
510+
EX_TABLE_UA_LOAD_REG(1b, 1b, %[rc], %[prev])
511+
: [rc] "+&d" (rc),
512+
[prev] "+&d" (prev),
513+
[address] "+Q" (*(int *)address)
514+
: [new] "d" ((unsigned int)new),
515+
[key] "a" (key << 4),
516+
[default_key] "J" (PAGE_DEFAULT_KEY)
517+
: "memory", "cc");
518+
*(unsigned int *)uval = prev;
519+
return rc;
520+
}
521+
case 8: {
522+
unsigned long prev = old;
523+
524+
asm volatile(
525+
" spka 0(%[key])\n"
526+
" sacf 256\n"
527+
"0: csg %[prev],%[new],%[address]\n"
528+
"1: sacf 768\n"
529+
" spka %[default_key]\n"
530+
EX_TABLE_UA_LOAD_REG(0b, 1b, %[rc], %[prev])
531+
EX_TABLE_UA_LOAD_REG(1b, 1b, %[rc], %[prev])
532+
: [rc] "+&d" (rc),
533+
[prev] "+&d" (prev),
534+
[address] "+QS" (*(long *)address)
535+
: [new] "d" ((unsigned long)new),
536+
[key] "a" (key << 4),
537+
[default_key] "J" (PAGE_DEFAULT_KEY)
538+
: "memory", "cc");
539+
*(unsigned long *)uval = prev;
540+
return rc;
541+
}
542+
case 16: {
543+
__uint128_t prev = old;
544+
545+
asm volatile(
546+
" spka 0(%[key])\n"
547+
" sacf 256\n"
548+
"0: cdsg %[prev],%[new],%[address]\n"
549+
"1: sacf 768\n"
550+
" spka %[default_key]\n"
551+
EX_TABLE_UA_LOAD_REGPAIR(0b, 1b, %[rc], %[prev])
552+
EX_TABLE_UA_LOAD_REGPAIR(1b, 1b, %[rc], %[prev])
553+
: [rc] "+&d" (rc),
554+
[prev] "+&d" (prev),
555+
[address] "+QS" (*(__int128_t *)address)
556+
: [new] "d" (new),
557+
[key] "a" (key << 4),
558+
[default_key] "J" (PAGE_DEFAULT_KEY)
559+
: "memory", "cc");
560+
*(__uint128_t *)uval = prev;
561+
return rc;
562+
}
563+
}
564+
__cmpxchg_user_key_called_with_bad_pointer();
565+
return rc;
566+
}
567+
568+
/**
569+
* cmpxchg_user_key() - cmpxchg with user space target, honoring storage keys
570+
* @ptr: User space address of value to compare to @old and exchange with
571+
* @new. Must be aligned to sizeof(*@ptr).
572+
* @uval: Address where the old value of *@ptr is written to.
573+
* @old: Old value. Compared to the content pointed to by @ptr in order to
574+
* determine if the exchange occurs. The old value read from *@ptr is
575+
* written to *@uval.
576+
* @new: New value to place at *@ptr.
577+
* @key: Access key to use for checking storage key protection.
578+
*
579+
* Perform a cmpxchg on a user space target, honoring storage key protection.
580+
* @key alone determines how key checking is performed, neither
581+
* storage-protection-override nor fetch-protection-override apply.
582+
* The caller must compare *@uval and @old to determine if values have been
583+
* exchanged. In case of an exception *@uval is set to zero.
584+
*
585+
* Return: 0: cmpxchg executed
586+
* -EFAULT: an exception happened when trying to access *@ptr
587+
* -EAGAIN: maxed out number of retries (byte and short only)
588+
*/
589+
#define cmpxchg_user_key(ptr, uval, old, new, key) \
590+
({ \
591+
__typeof__(ptr) __ptr = (ptr); \
592+
__typeof__(uval) __uval = (uval); \
593+
\
594+
BUILD_BUG_ON(sizeof(*(__ptr)) != sizeof(*(__uval))); \
595+
might_fault(); \
596+
__chk_user_ptr(__ptr); \
597+
__cmpxchg_user_key((unsigned long)(__ptr), (void *)(__uval), \
598+
(old), (new), (key), sizeof(*(__ptr))); \
599+
})
600+
393601
#endif /* __S390_UACCESS_H */

‎arch/s390/mm/extable.c‎

Lines changed: 7 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -47,13 +47,16 @@ static bool ex_handler_ua_load_mem(const struct exception_table_entry *ex, struc
4747
return true;
4848
}
4949

50-
static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex, struct pt_regs *regs)
50+
static bool ex_handler_ua_load_reg(const struct exception_table_entry *ex,
51+
bool pair, struct pt_regs *regs)
5152
{
5253
unsigned int reg_zero = FIELD_GET(EX_DATA_REG_ADDR, ex->data);
5354
unsigned int reg_err = FIELD_GET(EX_DATA_REG_ERR, ex->data);
5455

5556
regs->gprs[reg_err] = -EFAULT;
5657
regs->gprs[reg_zero] = 0;
58+
if (pair)
59+
regs->gprs[reg_zero + 1] = 0;
5760
regs->psw.addr = extable_fixup(ex);
5861
return true;
5962
}
@@ -75,7 +78,9 @@ bool fixup_exception(struct pt_regs *regs)
7578
case EX_TYPE_UA_LOAD_MEM:
7679
return ex_handler_ua_load_mem(ex, regs);
7780
case EX_TYPE_UA_LOAD_REG:
78-
return ex_handler_ua_load_reg(ex, regs);
81+
return ex_handler_ua_load_reg(ex, false, regs);
82+
case EX_TYPE_UA_LOAD_REGPAIR:
83+
return ex_handler_ua_load_reg(ex, true, regs);
7984
}
8085
panic("invalid exception table entry");
8186
}

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