From d691023b62bdf33ed84023330f4d2c77d2325b01 Mon Sep 17 00:00:00 2001 From: Jon Medhurst Date: Sun, 3 Jul 2011 15:04:26 +0100 Subject: [PATCH] ARM: kprobes: Decode 32-bit Thumb load/store single data item instructions We will reject probing of unprivileged load and store instructions. These rarely occur and writing test cases for them is difficult. Signed-off-by: Jon Medhurst Acked-by: Nicolas Pitre --- arch/arm/kernel/kprobes-thumb.c | 153 ++++++++++++++++++++++++++++++++ 1 file changed, 153 insertions(+) diff --git a/arch/arm/kernel/kprobes-thumb.c b/arch/arm/kernel/kprobes-thumb.c index bf1113c89b1..9be8bea2990 100644 --- a/arch/arm/kernel/kprobes-thumb.c +++ b/arch/arm/kernel/kprobes-thumb.c @@ -118,6 +118,44 @@ t32_simulate_branch(struct kprobe *p, struct pt_regs *regs) regs->ARM_pc = pc + (offset * 2); } +static void __kprobes +t32_simulate_ldr_literal(struct kprobe *p, struct pt_regs *regs) +{ + kprobe_opcode_t insn = p->opcode; + unsigned long addr = thumb_probe_pc(p) & ~3; + int rt = (insn >> 12) & 0xf; + unsigned long rtv; + + long offset = insn & 0xfff; + if (insn & 0x00800000) + addr += offset; + else + addr -= offset; + + if (insn & 0x00400000) { + /* LDR */ + rtv = *(unsigned long *)addr; + if (rt == 15) { + bx_write_pc(rtv, regs); + return; + } + } else if (insn & 0x00200000) { + /* LDRH */ + if (insn & 0x01000000) + rtv = *(s16 *)addr; + else + rtv = *(u16 *)addr; + } else { + /* LDRB */ + if (insn & 0x01000000) + rtv = *(s8 *)addr; + else + rtv = *(u8 *)addr; + } + + regs->uregs[rt] = rtv; +} + static enum kprobe_insn __kprobes t32_decode_ldmstm(kprobe_opcode_t insn, struct arch_specific_insn *asi) { @@ -158,6 +196,32 @@ t32_emulate_ldrdstrd(struct kprobe *p, struct pt_regs *regs) regs->uregs[rt2] = rt2v; } +static void __kprobes +t32_emulate_ldrstr(struct kprobe *p, struct pt_regs *regs) +{ + kprobe_opcode_t insn = p->opcode; + int rt = (insn >> 12) & 0xf; + int rn = (insn >> 16) & 0xf; + int rm = insn & 0xf; + + register unsigned long rtv asm("r0") = regs->uregs[rt]; + register unsigned long rnv asm("r2") = regs->uregs[rn]; + register unsigned long rmv asm("r3") = regs->uregs[rm]; + + __asm__ __volatile__ ( + "blx %[fn]" + : "=r" (rtv), "=r" (rnv) + : "0" (rtv), "1" (rnv), "r" (rmv), [fn] "r" (p->ainsn.insn_fn) + : "lr", "memory", "cc" + ); + + regs->uregs[rn] = rnv; /* Writeback base register */ + if (rt == 15) /* Can't be true for a STR as they aren't allowed */ + bx_write_pc(rtv, regs); + else + regs->uregs[rt] = rtv; +} + static void __kprobes t32_emulate_rd8rn16rm0_rwflags(struct kprobe *p, struct pt_regs *regs) { @@ -516,6 +580,87 @@ static const union decode_item t32_table_1111_100x_x0x1__1111[] = { DECODE_END }; +static const union decode_item t32_table_1111_100x[] = { + /* Store/Load single data item */ + + /* ??? 1111 100x x11x xxxx xxxx xxxx xxxx xxxx */ + DECODE_REJECT (0xfe600000, 0xf8600000), + + /* ??? 1111 1001 0101 xxxx xxxx xxxx xxxx xxxx */ + DECODE_REJECT (0xfff00000, 0xf9500000), + + /* ??? 1111 100x 0xxx xxxx xxxx 10x0 xxxx xxxx */ + DECODE_REJECT (0xfe800d00, 0xf8000800), + + /* STRBT 1111 1000 0000 xxxx xxxx 1110 xxxx xxxx */ + /* STRHT 1111 1000 0010 xxxx xxxx 1110 xxxx xxxx */ + /* STRT 1111 1000 0100 xxxx xxxx 1110 xxxx xxxx */ + /* LDRBT 1111 1000 0001 xxxx xxxx 1110 xxxx xxxx */ + /* LDRSBT 1111 1001 0001 xxxx xxxx 1110 xxxx xxxx */ + /* LDRHT 1111 1000 0011 xxxx xxxx 1110 xxxx xxxx */ + /* LDRSHT 1111 1001 0011 xxxx xxxx 1110 xxxx xxxx */ + /* LDRT 1111 1000 0101 xxxx xxxx 1110 xxxx xxxx */ + DECODE_REJECT (0xfe800f00, 0xf8000e00), + + /* STR{,B,H} Rn,[PC...] 1111 1000 xxx0 1111 xxxx xxxx xxxx xxxx */ + DECODE_REJECT (0xff1f0000, 0xf80f0000), + + /* STR{,B,H} PC,[Rn...] 1111 1000 xxx0 xxxx 1111 xxxx xxxx xxxx */ + DECODE_REJECT (0xff10f000, 0xf800f000), + + /* LDR (literal) 1111 1000 x101 1111 xxxx xxxx xxxx xxxx */ + DECODE_SIMULATEX(0xff7f0000, 0xf85f0000, t32_simulate_ldr_literal, + REGS(PC, ANY, 0, 0, 0)), + + /* STR (immediate) 1111 1000 0100 xxxx xxxx 1xxx xxxx xxxx */ + /* LDR (immediate) 1111 1000 0101 xxxx xxxx 1xxx xxxx xxxx */ + DECODE_OR (0xffe00800, 0xf8400800), + /* STR (immediate) 1111 1000 1100 xxxx xxxx xxxx xxxx xxxx */ + /* LDR (immediate) 1111 1000 1101 xxxx xxxx xxxx xxxx xxxx */ + DECODE_EMULATEX (0xffe00000, 0xf8c00000, t32_emulate_ldrstr, + REGS(NOPCX, ANY, 0, 0, 0)), + + /* STR (register) 1111 1000 0100 xxxx xxxx 0000 00xx xxxx */ + /* LDR (register) 1111 1000 0101 xxxx xxxx 0000 00xx xxxx */ + DECODE_EMULATEX (0xffe00fc0, 0xf8400000, t32_emulate_ldrstr, + REGS(NOPCX, ANY, 0, 0, NOSPPC)), + + /* LDRB (literal) 1111 1000 x001 1111 xxxx xxxx xxxx xxxx */ + /* LDRSB (literal) 1111 1001 x001 1111 xxxx xxxx xxxx xxxx */ + /* LDRH (literal) 1111 1000 x011 1111 xxxx xxxx xxxx xxxx */ + /* LDRSH (literal) 1111 1001 x011 1111 xxxx xxxx xxxx xxxx */ + DECODE_EMULATEX (0xfe5f0000, 0xf81f0000, t32_simulate_ldr_literal, + REGS(PC, NOSPPCX, 0, 0, 0)), + + /* STRB (immediate) 1111 1000 0000 xxxx xxxx 1xxx xxxx xxxx */ + /* STRH (immediate) 1111 1000 0010 xxxx xxxx 1xxx xxxx xxxx */ + /* LDRB (immediate) 1111 1000 0001 xxxx xxxx 1xxx xxxx xxxx */ + /* LDRSB (immediate) 1111 1001 0001 xxxx xxxx 1xxx xxxx xxxx */ + /* LDRH (immediate) 1111 1000 0011 xxxx xxxx 1xxx xxxx xxxx */ + /* LDRSH (immediate) 1111 1001 0011 xxxx xxxx 1xxx xxxx xxxx */ + DECODE_OR (0xfec00800, 0xf8000800), + /* STRB (immediate) 1111 1000 1000 xxxx xxxx xxxx xxxx xxxx */ + /* STRH (immediate) 1111 1000 1010 xxxx xxxx xxxx xxxx xxxx */ + /* LDRB (immediate) 1111 1000 1001 xxxx xxxx xxxx xxxx xxxx */ + /* LDRSB (immediate) 1111 1001 1001 xxxx xxxx xxxx xxxx xxxx */ + /* LDRH (immediate) 1111 1000 1011 xxxx xxxx xxxx xxxx xxxx */ + /* LDRSH (immediate) 1111 1001 1011 xxxx xxxx xxxx xxxx xxxx */ + DECODE_EMULATEX (0xfec00000, 0xf8800000, t32_emulate_ldrstr, + REGS(NOPCX, NOSPPCX, 0, 0, 0)), + + /* STRB (register) 1111 1000 0000 xxxx xxxx 0000 00xx xxxx */ + /* STRH (register) 1111 1000 0010 xxxx xxxx 0000 00xx xxxx */ + /* LDRB (register) 1111 1000 0001 xxxx xxxx 0000 00xx xxxx */ + /* LDRSB (register) 1111 1001 0001 xxxx xxxx 0000 00xx xxxx */ + /* LDRH (register) 1111 1000 0011 xxxx xxxx 0000 00xx xxxx */ + /* LDRSH (register) 1111 1001 0011 xxxx xxxx 0000 00xx xxxx */ + DECODE_EMULATEX (0xfe800fc0, 0xf8000000, t32_emulate_ldrstr, + REGS(NOPCX, NOSPPCX, 0, 0, NOSPPC)), + + /* Other unallocated instructions... */ + DECODE_END +}; + const union decode_item kprobe_decode_thumb32_table[] = { /* @@ -572,6 +717,14 @@ const union decode_item kprobe_decode_thumb32_table[] = { */ DECODE_TABLE (0xfe50f000, 0xf810f000, t32_table_1111_100x_x0x1__1111), + /* + * Store single data item + * 1111 1000 xxx0 xxxx xxxx xxxx xxxx xxxx + * Load single data items + * 1111 100x xxx1 xxxx xxxx xxxx xxxx xxxx + */ + DECODE_TABLE (0xfe000000, 0xf8000000, t32_table_1111_100x), + /* * Coprocessor instructions * 1111 11xx xxxx xxxx xxxx xxxx xxxx xxxx -- 2.39.5