include/asm/uaccess-asm.h

0001 /* SPDX-License-Identifier: GPL-2.0-only */
0002
0003 #ifndef __ASM_UACCESS_ASM_H__
0004 #define __ASM_UACCESS_ASM_H__
0005
0006 #include <asm/asm-offsets.h>
0007 #include <asm/domain.h>
0008 #include <asm/memory.h>
0009 #include <asm/thread_info.h>
0010
0011     .macro  csdb
0012 #ifdef CONFIG_THUMB2_KERNEL
0013     .inst.w 0xf3af8014
0014 #else
0015     .inst   0xe320f014
0016 #endif
0017     .endm
0018
0019     .macro check_uaccess, addr:req, size:req, limit:req, tmp:req, bad:req
0020 #ifndef CONFIG_CPU_USE_DOMAINS
0021     adds    \tmp, \addr, #\size - 1
0022     sbcscc  \tmp, \tmp, \limit
0023     bcs \bad
0024 #ifdef CONFIG_CPU_SPECTRE
0025     movcs   \addr, #0
0026     csdb
0027 #endif
0028 #endif
0029     .endm
0030
0031     .macro uaccess_mask_range_ptr, addr:req, size:req, limit:req, tmp:req
0032 #ifdef CONFIG_CPU_SPECTRE
0033     sub \tmp, \limit, #1
0034     subs    \tmp, \tmp, \addr   @ tmp = limit - 1 - addr
0035     addhs   \tmp, \tmp, #1      @ if (tmp >= 0) {
0036     subshs  \tmp, \tmp, \size   @ tmp = limit - (addr + size) }
0037     movlo   \addr, #0       @ if (tmp < 0) addr = NULL
0038     csdb
0039 #endif
0040     .endm
0041
0042     .macro  uaccess_disable, tmp, isb=1
0043 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
0044     /*
0045      * Whenever we re-enter userspace, the domains should always be
0046      * set appropriately.
0047      */
0048     mov \tmp, #DACR_UACCESS_DISABLE
0049     mcr p15, 0, \tmp, c3, c0, 0     @ Set domain register
0050     .if \isb
0051     instr_sync
0052     .endif
0053 #endif
0054     .endm
0055
0056     .macro  uaccess_enable, tmp, isb=1
0057 #ifdef CONFIG_CPU_SW_DOMAIN_PAN
0058     /*
0059      * Whenever we re-enter userspace, the domains should always be
0060      * set appropriately.
0061      */
0062     mov \tmp, #DACR_UACCESS_ENABLE
0063     mcr p15, 0, \tmp, c3, c0, 0
0064     .if \isb
0065     instr_sync
0066     .endif
0067 #endif
0068     .endm
0069
0070 #if defined(CONFIG_CPU_SW_DOMAIN_PAN) || defined(CONFIG_CPU_USE_DOMAINS)
0071 #define DACR(x...)  x
0072 #else
0073 #define DACR(x...)
0074 #endif
0075
0076     /*
0077      * Save the address limit on entry to a privileged exception.
0078      *
0079      * If we are using the DACR for kernel access by the user accessors
0080      * (CONFIG_CPU_USE_DOMAINS=y), always reset the DACR kernel domain
0081      * back to client mode, whether or not \disable is set.
0082      *
0083      * If we are using SW PAN, set the DACR user domain to no access
0084      * if \disable is set.
0085      */
0086     .macro  uaccess_entry, tsk, tmp0, tmp1, tmp2, disable
0087  DACR(  mrc p15, 0, \tmp0, c3, c0, 0)
0088  DACR(  str \tmp0, [sp, #SVC_DACR])
0089     .if \disable && IS_ENABLED(CONFIG_CPU_SW_DOMAIN_PAN)
0090     /* kernel=client, user=no access */
0091     mov \tmp2, #DACR_UACCESS_DISABLE
0092     mcr p15, 0, \tmp2, c3, c0, 0
0093     instr_sync
0094     .elseif IS_ENABLED(CONFIG_CPU_USE_DOMAINS)
0095     /* kernel=client */
0096     bic \tmp2, \tmp0, #domain_mask(DOMAIN_KERNEL)
0097     orr \tmp2, \tmp2, #domain_val(DOMAIN_KERNEL, DOMAIN_CLIENT)
0098     mcr p15, 0, \tmp2, c3, c0, 0
0099     instr_sync
0100     .endif
0101     .endm
0102
0103     /* Restore the user access state previously saved by uaccess_entry */
0104     .macro  uaccess_exit, tsk, tmp0, tmp1
0105  DACR(  ldr \tmp0, [sp, #SVC_DACR])
0106  DACR(  mcr p15, 0, \tmp0, c3, c0, 0)
0107     .endm
0108
0109 #undef DACR
0110
0111 #endif /* __ASM_UACCESS_ASM_H__ */