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-rw-r--r--arch/arc/kernel/unaligned.c262
1 files changed, 262 insertions, 0 deletions
diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c
new file mode 100644
index 000000000..99a9b92ed
--- /dev/null
+++ b/arch/arc/kernel/unaligned.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011-2012 Synopsys (www.synopsys.com)
+ *
+ * vineetg : May 2011
+ * -Adapted (from .26 to .35)
+ * -original contribution by Tim.yao@amlogic.com
+ */
+
+#include <linux/types.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>
+#include <linux/uaccess.h>
+#include <asm/disasm.h>
+
+#ifdef CONFIG_CPU_BIG_ENDIAN
+#define BE 1
+#define FIRST_BYTE_16 "swap %1, %1\n swape %1, %1\n"
+#define FIRST_BYTE_32 "swape %1, %1\n"
+#else
+#define BE 0
+#define FIRST_BYTE_16
+#define FIRST_BYTE_32
+#endif
+
+#define __get8_unaligned_check(val, addr, err) \
+ __asm__( \
+ "1: ldb.ab %1, [%2, 1]\n" \
+ "2:\n" \
+ " .section .fixup,\"ax\"\n" \
+ " .align 4\n" \
+ "3: mov %0, 1\n" \
+ " j 2b\n" \
+ " .previous\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 4\n" \
+ " .long 1b, 3b\n" \
+ " .previous\n" \
+ : "=r" (err), "=&r" (val), "=r" (addr) \
+ : "0" (err), "2" (addr))
+
+#define get16_unaligned_check(val, addr) \
+ do { \
+ unsigned int err = 0, v, a = addr; \
+ __get8_unaligned_check(v, a, err); \
+ val = v << ((BE) ? 8 : 0); \
+ __get8_unaligned_check(v, a, err); \
+ val |= v << ((BE) ? 0 : 8); \
+ if (err) \
+ goto fault; \
+ } while (0)
+
+#define get32_unaligned_check(val, addr) \
+ do { \
+ unsigned int err = 0, v, a = addr; \
+ __get8_unaligned_check(v, a, err); \
+ val = v << ((BE) ? 24 : 0); \
+ __get8_unaligned_check(v, a, err); \
+ val |= v << ((BE) ? 16 : 8); \
+ __get8_unaligned_check(v, a, err); \
+ val |= v << ((BE) ? 8 : 16); \
+ __get8_unaligned_check(v, a, err); \
+ val |= v << ((BE) ? 0 : 24); \
+ if (err) \
+ goto fault; \
+ } while (0)
+
+#define put16_unaligned_check(val, addr) \
+ do { \
+ unsigned int err = 0, v = val, a = addr;\
+ \
+ __asm__( \
+ FIRST_BYTE_16 \
+ "1: stb.ab %1, [%2, 1]\n" \
+ " lsr %1, %1, 8\n" \
+ "2: stb %1, [%2]\n" \
+ "3:\n" \
+ " .section .fixup,\"ax\"\n" \
+ " .align 4\n" \
+ "4: mov %0, 1\n" \
+ " j 3b\n" \
+ " .previous\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 4\n" \
+ " .long 1b, 4b\n" \
+ " .long 2b, 4b\n" \
+ " .previous\n" \
+ : "=r" (err), "=&r" (v), "=&r" (a) \
+ : "0" (err), "1" (v), "2" (a)); \
+ \
+ if (err) \
+ goto fault; \
+ } while (0)
+
+#define put32_unaligned_check(val, addr) \
+ do { \
+ unsigned int err = 0, v = val, a = addr;\
+ \
+ __asm__( \
+ FIRST_BYTE_32 \
+ "1: stb.ab %1, [%2, 1]\n" \
+ " lsr %1, %1, 8\n" \
+ "2: stb.ab %1, [%2, 1]\n" \
+ " lsr %1, %1, 8\n" \
+ "3: stb.ab %1, [%2, 1]\n" \
+ " lsr %1, %1, 8\n" \
+ "4: stb %1, [%2]\n" \
+ "5:\n" \
+ " .section .fixup,\"ax\"\n" \
+ " .align 4\n" \
+ "6: mov %0, 1\n" \
+ " j 5b\n" \
+ " .previous\n" \
+ " .section __ex_table,\"a\"\n" \
+ " .align 4\n" \
+ " .long 1b, 6b\n" \
+ " .long 2b, 6b\n" \
+ " .long 3b, 6b\n" \
+ " .long 4b, 6b\n" \
+ " .previous\n" \
+ : "=r" (err), "=&r" (v), "=&r" (a) \
+ : "0" (err), "1" (v), "2" (a)); \
+ \
+ if (err) \
+ goto fault; \
+ } while (0)
+
+/* sysctl hooks */
+int unaligned_enabled __read_mostly = 1; /* Enabled by default */
+int no_unaligned_warning __read_mostly = 1; /* Only 1 warning by default */
+
+static void fixup_load(struct disasm_state *state, struct pt_regs *regs,
+ struct callee_regs *cregs)
+{
+ int val;
+
+ /* register write back */
+ if ((state->aa == 1) || (state->aa == 2)) {
+ set_reg(state->wb_reg, state->src1 + state->src2, regs, cregs);
+
+ if (state->aa == 2)
+ state->src2 = 0;
+ }
+
+ if (state->zz == 0) {
+ get32_unaligned_check(val, state->src1 + state->src2);
+ } else {
+ get16_unaligned_check(val, state->src1 + state->src2);
+
+ if (state->x)
+ val = (val << 16) >> 16;
+ }
+
+ if (state->pref == 0)
+ set_reg(state->dest, val, regs, cregs);
+
+ return;
+
+fault: state->fault = 1;
+}
+
+static void fixup_store(struct disasm_state *state, struct pt_regs *regs,
+ struct callee_regs *cregs)
+{
+ /* register write back */
+ if ((state->aa == 1) || (state->aa == 2)) {
+ set_reg(state->wb_reg, state->src2 + state->src3, regs, cregs);
+
+ if (state->aa == 3)
+ state->src3 = 0;
+ } else if (state->aa == 3) {
+ if (state->zz == 2) {
+ set_reg(state->wb_reg, state->src2 + (state->src3 << 1),
+ regs, cregs);
+ } else if (!state->zz) {
+ set_reg(state->wb_reg, state->src2 + (state->src3 << 2),
+ regs, cregs);
+ } else {
+ goto fault;
+ }
+ }
+
+ /* write fix-up */
+ if (!state->zz)
+ put32_unaligned_check(state->src1, state->src2 + state->src3);
+ else
+ put16_unaligned_check(state->src1, state->src2 + state->src3);
+
+ return;
+
+fault: state->fault = 1;
+}
+
+/*
+ * Handle an unaligned access
+ * Returns 0 if successfully handled, 1 if some error happened
+ */
+int misaligned_fixup(unsigned long address, struct pt_regs *regs,
+ struct callee_regs *cregs)
+{
+ struct disasm_state state;
+ char buf[TASK_COMM_LEN];
+
+ /* handle user mode only and only if enabled by sysadmin */
+ if (!user_mode(regs) || !unaligned_enabled)
+ return 1;
+
+ if (no_unaligned_warning) {
+ pr_warn_once("%s(%d) made unaligned access which was emulated"
+ " by kernel assist\n. This can degrade application"
+ " performance significantly\n. To enable further"
+ " logging of such instances, please \n"
+ " echo 0 > /proc/sys/kernel/ignore-unaligned-usertrap\n",
+ get_task_comm(buf, current), task_pid_nr(current));
+ } else {
+ /* Add rate limiting if it gets down to it */
+ pr_warn("%s(%d): unaligned access to/from 0x%lx by PC: 0x%lx\n",
+ get_task_comm(buf, current), task_pid_nr(current),
+ address, regs->ret);
+
+ }
+
+ disasm_instr(regs->ret, &state, 1, regs, cregs);
+
+ if (state.fault)
+ goto fault;
+
+ /* ldb/stb should not have unaligned exception */
+ if ((state.zz == 1) || (state.di))
+ goto fault;
+
+ if (!state.write)
+ fixup_load(&state, regs, cregs);
+ else
+ fixup_store(&state, regs, cregs);
+
+ if (state.fault)
+ goto fault;
+
+ /* clear any remnants of delay slot */
+ if (delay_mode(regs)) {
+ regs->ret = regs->bta & ~1U;
+ regs->status32 &= ~STATUS_DE_MASK;
+ } else {
+ regs->ret += state.instr_len;
+
+ /* handle zero-overhead-loop */
+ if ((regs->ret == regs->lp_end) && (regs->lp_count)) {
+ regs->ret = regs->lp_start;
+ regs->lp_count--;
+ }
+ }
+
+ perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, address);
+ return 0;
+
+fault:
+ pr_err("Alignment trap: fault in fix-up %08lx at [<%08lx>]\n",
+ state.words[0], address);
+
+ return 1;
+}
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