From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/arm64/kernel/compat_alignment.c | 383 +++++++++++++++++++++++++++++++++++ 1 file changed, 383 insertions(+) create mode 100644 arch/arm64/kernel/compat_alignment.c (limited to 'arch/arm64/kernel/compat_alignment.c') diff --git a/arch/arm64/kernel/compat_alignment.c b/arch/arm64/kernel/compat_alignment.c new file mode 100644 index 000000000..deff21bfa --- /dev/null +++ b/arch/arm64/kernel/compat_alignment.c @@ -0,0 +1,383 @@ +// SPDX-License-Identifier: GPL-2.0-only +// based on arch/arm/mm/alignment.c + +#include +#include +#include +#include +#include +#include + +#include +#include +#include + +/* + * 32-bit misaligned trap handler (c) 1998 San Mehat (CCC) -July 1998 + * + * Speed optimisations and better fault handling by Russell King. + */ +#define CODING_BITS(i) (i & 0x0e000000) + +#define LDST_P_BIT(i) (i & (1 << 24)) /* Preindex */ +#define LDST_U_BIT(i) (i & (1 << 23)) /* Add offset */ +#define LDST_W_BIT(i) (i & (1 << 21)) /* Writeback */ +#define LDST_L_BIT(i) (i & (1 << 20)) /* Load */ + +#define LDST_P_EQ_U(i) ((((i) ^ ((i) >> 1)) & (1 << 23)) == 0) + +#define LDSTHD_I_BIT(i) (i & (1 << 22)) /* double/half-word immed */ + +#define RN_BITS(i) ((i >> 16) & 15) /* Rn */ +#define RD_BITS(i) ((i >> 12) & 15) /* Rd */ +#define RM_BITS(i) (i & 15) /* Rm */ + +#define REGMASK_BITS(i) (i & 0xffff) + +#define BAD_INSTR 0xdeadc0de + +/* Thumb-2 32 bit format per ARMv7 DDI0406A A6.3, either f800h,e800h,f800h */ +#define IS_T32(hi16) \ + (((hi16) & 0xe000) == 0xe000 && ((hi16) & 0x1800)) + +union offset_union { + unsigned long un; + signed long sn; +}; + +#define TYPE_ERROR 0 +#define TYPE_FAULT 1 +#define TYPE_LDST 2 +#define TYPE_DONE 3 + +static void +do_alignment_finish_ldst(unsigned long addr, u32 instr, struct pt_regs *regs, + union offset_union offset) +{ + if (!LDST_U_BIT(instr)) + offset.un = -offset.un; + + if (!LDST_P_BIT(instr)) + addr += offset.un; + + if (!LDST_P_BIT(instr) || LDST_W_BIT(instr)) + regs->regs[RN_BITS(instr)] = addr; +} + +static int +do_alignment_ldrdstrd(unsigned long addr, u32 instr, struct pt_regs *regs) +{ + unsigned int rd = RD_BITS(instr); + unsigned int rd2; + int load; + + if ((instr & 0xfe000000) == 0xe8000000) { + /* ARMv7 Thumb-2 32-bit LDRD/STRD */ + rd2 = (instr >> 8) & 0xf; + load = !!(LDST_L_BIT(instr)); + } else if (((rd & 1) == 1) || (rd == 14)) { + return TYPE_ERROR; + } else { + load = ((instr & 0xf0) == 0xd0); + rd2 = rd + 1; + } + + if (load) { + unsigned int val, val2; + + if (get_user(val, (u32 __user *)addr) || + get_user(val2, (u32 __user *)(addr + 4))) + return TYPE_FAULT; + regs->regs[rd] = val; + regs->regs[rd2] = val2; + } else { + if (put_user(regs->regs[rd], (u32 __user *)addr) || + put_user(regs->regs[rd2], (u32 __user *)(addr + 4))) + return TYPE_FAULT; + } + return TYPE_LDST; +} + +/* + * LDM/STM alignment handler. + * + * There are 4 variants of this instruction: + * + * B = rn pointer before instruction, A = rn pointer after instruction + * ------ increasing address -----> + * | | r0 | r1 | ... | rx | | + * PU = 01 B A + * PU = 11 B A + * PU = 00 A B + * PU = 10 A B + */ +static int +do_alignment_ldmstm(unsigned long addr, u32 instr, struct pt_regs *regs) +{ + unsigned int rd, rn, nr_regs, regbits; + unsigned long eaddr, newaddr; + unsigned int val; + + /* count the number of registers in the mask to be transferred */ + nr_regs = hweight16(REGMASK_BITS(instr)) * 4; + + rn = RN_BITS(instr); + newaddr = eaddr = regs->regs[rn]; + + if (!LDST_U_BIT(instr)) + nr_regs = -nr_regs; + newaddr += nr_regs; + if (!LDST_U_BIT(instr)) + eaddr = newaddr; + + if (LDST_P_EQ_U(instr)) /* U = P */ + eaddr += 4; + + for (regbits = REGMASK_BITS(instr), rd = 0; regbits; + regbits >>= 1, rd += 1) + if (regbits & 1) { + if (LDST_L_BIT(instr)) { + if (get_user(val, (u32 __user *)eaddr)) + return TYPE_FAULT; + if (rd < 15) + regs->regs[rd] = val; + else + regs->pc = val; + } else { + /* + * The PC register has a bias of +8 in ARM mode + * and +4 in Thumb mode. This means that a read + * of the value of PC should account for this. + * Since Thumb does not permit STM instructions + * to refer to PC, just add 8 here. + */ + val = (rd < 15) ? regs->regs[rd] : regs->pc + 8; + if (put_user(val, (u32 __user *)eaddr)) + return TYPE_FAULT; + } + eaddr += 4; + } + + if (LDST_W_BIT(instr)) + regs->regs[rn] = newaddr; + + return TYPE_DONE; +} + +/* + * Convert Thumb multi-word load/store instruction forms to equivalent ARM + * instructions so we can reuse ARM userland alignment fault fixups for Thumb. + * + * This implementation was initially based on the algorithm found in + * gdb/sim/arm/thumbemu.c. It is basically just a code reduction of same + * to convert only Thumb ld/st instruction forms to equivalent ARM forms. + * + * NOTES: + * 1. Comments below refer to ARM ARM DDI0100E Thumb Instruction sections. + * 2. If for some reason we're passed an non-ld/st Thumb instruction to + * decode, we return 0xdeadc0de. This should never happen under normal + * circumstances but if it does, we've got other problems to deal with + * elsewhere and we obviously can't fix those problems here. + */ + +static unsigned long thumb2arm(u16 tinstr) +{ + u32 L = (tinstr & (1<<11)) >> 11; + + switch ((tinstr & 0xf800) >> 11) { + /* 6.6.1 Format 1: */ + case 0xc000 >> 11: /* 7.1.51 STMIA */ + case 0xc800 >> 11: /* 7.1.25 LDMIA */ + { + u32 Rn = (tinstr & (7<<8)) >> 8; + u32 W = ((L<> 11: /* 7.1.48 PUSH */ + case 0xb800 >> 11: /* 7.1.47 POP */ + if ((tinstr & (3 << 9)) == 0x0400) { + static const u32 subset[4] = { + 0xe92d0000, /* STMDB sp!,{registers} */ + 0xe92d4000, /* STMDB sp!,{registers,lr} */ + 0xe8bd0000, /* LDMIA sp!,{registers} */ + 0xe8bd8000 /* LDMIA sp!,{registers,pc} */ + }; + return subset[(L<<1) | ((tinstr & (1<<8)) >> 8)] | + (tinstr & 255); /* register_list */ + } + fallthrough; /* for illegal instruction case */ + + default: + return BAD_INSTR; + } +} + +/* + * Convert Thumb-2 32 bit LDM, STM, LDRD, STRD to equivalent instruction + * handlable by ARM alignment handler, also find the corresponding handler, + * so that we can reuse ARM userland alignment fault fixups for Thumb. + * + * @pinstr: original Thumb-2 instruction; returns new handlable instruction + * @regs: register context. + * @poffset: return offset from faulted addr for later writeback + * + * NOTES: + * 1. Comments below refer to ARMv7 DDI0406A Thumb Instruction sections. + * 2. Register name Rt from ARMv7 is same as Rd from ARMv6 (Rd is Rt) + */ +static void * +do_alignment_t32_to_handler(u32 *pinstr, struct pt_regs *regs, + union offset_union *poffset) +{ + u32 instr = *pinstr; + u16 tinst1 = (instr >> 16) & 0xffff; + u16 tinst2 = instr & 0xffff; + + switch (tinst1 & 0xffe0) { + /* A6.3.5 Load/Store multiple */ + case 0xe880: /* STM/STMIA/STMEA,LDM/LDMIA, PUSH/POP T2 */ + case 0xe8a0: /* ...above writeback version */ + case 0xe900: /* STMDB/STMFD, LDMDB/LDMEA */ + case 0xe920: /* ...above writeback version */ + /* no need offset decision since handler calculates it */ + return do_alignment_ldmstm; + + case 0xf840: /* POP/PUSH T3 (single register) */ + if (RN_BITS(instr) == 13 && (tinst2 & 0x09ff) == 0x0904) { + u32 L = !!(LDST_L_BIT(instr)); + const u32 subset[2] = { + 0xe92d0000, /* STMDB sp!,{registers} */ + 0xe8bd0000, /* LDMIA sp!,{registers} */ + }; + *pinstr = subset[L] | (1<un = (tinst2 & 0xff) << 2; + fallthrough; + + case 0xe940: + case 0xe9c0: + return do_alignment_ldrdstrd; + + /* + * No need to handle load/store instructions up to word size + * since ARMv6 and later CPUs can perform unaligned accesses. + */ + default: + break; + } + return NULL; +} + +static int alignment_get_arm(struct pt_regs *regs, __le32 __user *ip, u32 *inst) +{ + __le32 instr = 0; + int fault; + + fault = get_user(instr, ip); + if (fault) + return fault; + + *inst = __le32_to_cpu(instr); + return 0; +} + +static int alignment_get_thumb(struct pt_regs *regs, __le16 __user *ip, u16 *inst) +{ + __le16 instr = 0; + int fault; + + fault = get_user(instr, ip); + if (fault) + return fault; + + *inst = __le16_to_cpu(instr); + return 0; +} + +int do_compat_alignment_fixup(unsigned long addr, struct pt_regs *regs) +{ + union offset_union offset; + unsigned long instrptr; + int (*handler)(unsigned long addr, u32 instr, struct pt_regs *regs); + unsigned int type; + u32 instr = 0; + int isize = 4; + int thumb2_32b = 0; + + instrptr = instruction_pointer(regs); + + if (compat_thumb_mode(regs)) { + __le16 __user *ptr = (__le16 __user *)(instrptr & ~1); + u16 tinstr, tinst2; + + if (alignment_get_thumb(regs, ptr, &tinstr)) + return 1; + + if (IS_T32(tinstr)) { /* Thumb-2 32-bit */ + if (alignment_get_thumb(regs, ptr + 1, &tinst2)) + return 1; + instr = ((u32)tinstr << 16) | tinst2; + thumb2_32b = 1; + } else { + isize = 2; + instr = thumb2arm(tinstr); + } + } else { + if (alignment_get_arm(regs, (__le32 __user *)instrptr, &instr)) + return 1; + } + + switch (CODING_BITS(instr)) { + case 0x00000000: /* 3.13.4 load/store instruction extensions */ + if (LDSTHD_I_BIT(instr)) + offset.un = (instr & 0xf00) >> 4 | (instr & 15); + else + offset.un = regs->regs[RM_BITS(instr)]; + + if ((instr & 0x001000f0) == 0x000000d0 || /* LDRD */ + (instr & 0x001000f0) == 0x000000f0) /* STRD */ + handler = do_alignment_ldrdstrd; + else + return 1; + break; + + case 0x08000000: /* ldm or stm, or thumb-2 32bit instruction */ + if (thumb2_32b) { + offset.un = 0; + handler = do_alignment_t32_to_handler(&instr, regs, &offset); + } else { + offset.un = 0; + handler = do_alignment_ldmstm; + } + break; + + default: + return 1; + } + + type = handler(addr, instr, regs); + + if (type == TYPE_ERROR || type == TYPE_FAULT) + return 1; + + if (type == TYPE_LDST) + do_alignment_finish_ldst(addr, instr, regs, offset); + + perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, regs->pc); + arm64_skip_faulting_instruction(regs, isize); + + return 0; +} -- cgit v1.2.3