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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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f61698e648
Sparc optimized memset (arch/sparc/lib/memset.S) does not fill last
byte of the memory area, if area size is less than 8 bytes and start
address is not word (4-bytes) aligned.
Here is code chunk where bug located:
/* %o0 - memory address, %o1 - size, %g3 - value */
8:
add %o0, 1, %o0
subcc %o1, 1, %o1
bne,a 8b
stb %g3, [%o0 - 1]
This code should write byte every loop iteration, but last time delay
instruction stb is not executed because branch instruction sets
"annul" bit.
Patch replaces bne,a by bne instruction.
Error can be reproduced by simple kernel module:
--------------------
#include <linux/module.h>
#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <string.h>
static void do_memset(void **p, int size)
{
memset(p, 0x00, size);
}
static int __init memset_test_init(void)
{
char fooc[8];
int *fooi;
memset(fooc, 0xba, sizeof(fooc));
do_memset((void**)(fooc + 3), 1);
fooi = (int*) fooc;
printk("%08X %08X\n", fooi[0], fooi[1]);
return -1;
}
static void __exit memset_test_cleanup(void)
{
return;
}
module_init(memset_test_init);
module_exit(memset_test_cleanup);
MODULE_LICENSE("GPL");
EXPORT_NO_SYMBOLS;
--------------------
Signed-off-by: Alexander Shmelev <ashmelev@task.sun.mcst.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>
204 lines
3.7 KiB
ArmAsm
204 lines
3.7 KiB
ArmAsm
/* linux/arch/sparc/lib/memset.S: Sparc optimized memset, bzero and clear_user code
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* Copyright (C) 1991,1996 Free Software Foundation
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* Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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* Copyright (C) 1996 David S. Miller (davem@caip.rutgers.edu)
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*
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* Returns 0, if ok, and number of bytes not yet set if exception
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* occurs and we were called as clear_user.
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*/
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#include <asm/ptrace.h>
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/* Work around cpp -rob */
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#define ALLOC #alloc
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#define EXECINSTR #execinstr
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#define EX(x,y,a,b) \
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98: x,y; \
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.section .fixup,ALLOC,EXECINSTR; \
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.align 4; \
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99: ba 30f; \
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a, b, %o0; \
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.section __ex_table,ALLOC; \
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.align 4; \
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.word 98b, 99b; \
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.text; \
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.align 4
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#define EXT(start,end,handler) \
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.section __ex_table,ALLOC; \
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.align 4; \
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.word start, 0, end, handler; \
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.text; \
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.align 4
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/* Please don't change these macros, unless you change the logic
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* in the .fixup section below as well.
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* Store 64 bytes at (BASE + OFFSET) using value SOURCE. */
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#define ZERO_BIG_BLOCK(base, offset, source) \
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std source, [base + offset + 0x00]; \
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std source, [base + offset + 0x08]; \
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std source, [base + offset + 0x10]; \
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std source, [base + offset + 0x18]; \
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std source, [base + offset + 0x20]; \
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std source, [base + offset + 0x28]; \
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std source, [base + offset + 0x30]; \
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std source, [base + offset + 0x38];
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#define ZERO_LAST_BLOCKS(base, offset, source) \
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std source, [base - offset - 0x38]; \
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std source, [base - offset - 0x30]; \
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std source, [base - offset - 0x28]; \
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std source, [base - offset - 0x20]; \
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std source, [base - offset - 0x18]; \
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std source, [base - offset - 0x10]; \
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std source, [base - offset - 0x08]; \
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std source, [base - offset - 0x00];
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.text
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.align 4
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.globl __bzero_begin
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__bzero_begin:
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.globl __bzero, __memset,
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.globl memset
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.globl __memset_start, __memset_end
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__memset_start:
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__memset:
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memset:
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and %o1, 0xff, %g3
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sll %g3, 8, %g2
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or %g3, %g2, %g3
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sll %g3, 16, %g2
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or %g3, %g2, %g3
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b 1f
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mov %o2, %o1
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3:
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cmp %o2, 3
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be 2f
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EX(stb %g3, [%o0], sub %o1, 0)
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cmp %o2, 2
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be 2f
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EX(stb %g3, [%o0 + 0x01], sub %o1, 1)
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EX(stb %g3, [%o0 + 0x02], sub %o1, 2)
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2:
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sub %o2, 4, %o2
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add %o1, %o2, %o1
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b 4f
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sub %o0, %o2, %o0
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__bzero:
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mov %g0, %g3
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1:
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cmp %o1, 7
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bleu 7f
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andcc %o0, 3, %o2
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bne 3b
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4:
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andcc %o0, 4, %g0
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be 2f
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mov %g3, %g2
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EX(st %g3, [%o0], sub %o1, 0)
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sub %o1, 4, %o1
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add %o0, 4, %o0
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2:
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andcc %o1, 0xffffff80, %o3 ! Now everything is 8 aligned and o1 is len to run
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be 9f
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andcc %o1, 0x78, %o2
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10:
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ZERO_BIG_BLOCK(%o0, 0x00, %g2)
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subcc %o3, 128, %o3
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ZERO_BIG_BLOCK(%o0, 0x40, %g2)
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11:
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EXT(10b, 11b, 20f)
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bne 10b
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add %o0, 128, %o0
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orcc %o2, %g0, %g0
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9:
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be 13f
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andcc %o1, 7, %o1
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srl %o2, 1, %o3
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set 13f, %o4
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sub %o4, %o3, %o4
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jmp %o4
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add %o0, %o2, %o0
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12:
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ZERO_LAST_BLOCKS(%o0, 0x48, %g2)
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ZERO_LAST_BLOCKS(%o0, 0x08, %g2)
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13:
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be 8f
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andcc %o1, 4, %g0
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be 1f
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andcc %o1, 2, %g0
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EX(st %g3, [%o0], and %o1, 7)
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add %o0, 4, %o0
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1:
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be 1f
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andcc %o1, 1, %g0
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EX(sth %g3, [%o0], and %o1, 3)
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add %o0, 2, %o0
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1:
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bne,a 8f
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EX(stb %g3, [%o0], and %o1, 1)
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8:
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retl
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clr %o0
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7:
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be 13b
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orcc %o1, 0, %g0
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be 0f
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8:
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add %o0, 1, %o0
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subcc %o1, 1, %o1
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bne 8b
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EX(stb %g3, [%o0 - 1], add %o1, 1)
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0:
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retl
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clr %o0
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__memset_end:
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.section .fixup,#alloc,#execinstr
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.align 4
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20:
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cmp %g2, 8
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bleu 1f
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and %o1, 0x7f, %o1
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sub %g2, 9, %g2
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add %o3, 64, %o3
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1:
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sll %g2, 3, %g2
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add %o3, %o1, %o0
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b 30f
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sub %o0, %g2, %o0
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21:
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mov 8, %o0
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and %o1, 7, %o1
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sub %o0, %g2, %o0
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sll %o0, 3, %o0
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b 30f
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add %o0, %o1, %o0
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30:
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/* %o4 is faulting address, %o5 is %pc where fault occurred */
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save %sp, -104, %sp
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mov %i5, %o0
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mov %i7, %o1
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call lookup_fault
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mov %i4, %o2
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ret
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restore
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.globl __bzero_end
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__bzero_end:
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