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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 | /* SPDX-License-Identifier: GPL-2.0-only */ /* * sigreturn_codes.S - code sinpets for sigreturn syscalls * * Created by: Victor Kamensky, 2013-08-13 * Copyright: (C) 2013 Linaro Limited */ #include <asm/assembler.h> #include <asm/asm-offsets.h> #include <asm/unistd.h> /* * For ARM syscalls, we encode the syscall number into the instruction. * With EABI, the syscall number has to be loaded into r7. As result * ARM syscall sequence snippet will have move and svc in .arm encoding * * For Thumb syscalls, we pass the syscall number via r7. We therefore * need two 16-bit instructions in .thumb encoding * * Please note sigreturn_codes code are not executed in place. Instead * they just copied by kernel into appropriate places. Code inside of * arch/arm/kernel/signal.c is very sensitive to layout of these code * snippets. */ /* * In CPU_THUMBONLY case kernel arm opcodes are not allowed. * Note in this case codes skips those instructions but it uses .org * directive to keep correct layout of sigreturn_codes array. */ #ifndef CONFIG_CPU_THUMBONLY #define ARM_OK(code...) code #else #define ARM_OK(code...) #endif .macro arm_slot n .org sigreturn_codes + 12 * (\n) ARM_OK( .arm ) .endm .macro thumb_slot n .org sigreturn_codes + 12 * (\n) + 8 .thumb .endm .macro arm_fdpic_slot n .org sigreturn_codes + 24 + 20 * (\n) ARM_OK( .arm ) .endm .macro thumb_fdpic_slot n .org sigreturn_codes + 24 + 20 * (\n) + 12 .thumb .endm #if __LINUX_ARM_ARCH__ <= 4 /* * Note we manually set minimally required arch that supports * required thumb opcodes for early arch versions. It is OK * for this file to be used in combination with other * lower arch variants, since these code snippets are only * used as input data. */ .arch armv4t #endif .section .rodata .global sigreturn_codes .type sigreturn_codes, #object .align sigreturn_codes: /* ARM sigreturn syscall code snippet */ arm_slot 0 ARM_OK( mov r7, #(__NR_sigreturn - __NR_SYSCALL_BASE) ) ARM_OK( swi #(__NR_sigreturn)|(__NR_OABI_SYSCALL_BASE) ) /* Thumb sigreturn syscall code snippet */ thumb_slot 0 movs r7, #(__NR_sigreturn - __NR_SYSCALL_BASE) swi #0 /* ARM sigreturn_rt syscall code snippet */ arm_slot 1 ARM_OK( mov r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE) ) ARM_OK( swi #(__NR_rt_sigreturn)|(__NR_OABI_SYSCALL_BASE) ) /* Thumb sigreturn_rt syscall code snippet */ thumb_slot 1 movs r7, #(__NR_rt_sigreturn - __NR_SYSCALL_BASE) swi #0 /* ARM sigreturn restorer FDPIC bounce code snippet */ arm_fdpic_slot 0 ARM_OK( ldr r3, [sp, #SIGFRAME_RC3_OFFSET] ) ARM_OK( ldmia r3, {r3, r9} ) #ifdef CONFIG_ARM_THUMB ARM_OK( bx r3 ) #else ARM_OK( ret r3 ) #endif /* Thumb sigreturn restorer FDPIC bounce code snippet */ thumb_fdpic_slot 0 ldr r3, [sp, #SIGFRAME_RC3_OFFSET] ldmia r3, {r2, r3} mov r9, r3 bx r2 /* ARM sigreturn_rt restorer FDPIC bounce code snippet */ arm_fdpic_slot 1 ARM_OK( ldr r3, [sp, #RT_SIGFRAME_RC3_OFFSET] ) ARM_OK( ldmia r3, {r3, r9} ) #ifdef CONFIG_ARM_THUMB ARM_OK( bx r3 ) #else ARM_OK( ret r3 ) #endif /* Thumb sigreturn_rt restorer FDPIC bounce code snippet */ thumb_fdpic_slot 1 ldr r3, [sp, #RT_SIGFRAME_RC3_OFFSET] ldmia r3, {r2, r3} mov r9, r3 bx r2 /* * Note on additional space: setup_return in signal.c * always copies the same number of words regardless whether * it is thumb case or not, so we need one additional padding * word after the last entry. */ .space 4 .size sigreturn_codes, . - sigreturn_codes |