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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 08/15] xen/arm: arm64: Add helpers to decode and encode branch instructions
We may need to update branch instruction when patching Xen.
The code has been imported from the files arch/arm64/kernel/insn.c
and arch/arm64/include/asm/insn.h in Linux v4.6.
Note that only the necessary helpers have been imported.
Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
Acked-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
Changes in v3:
- Add Stefano's acked-by
Changes in v2:
- Re-sync with Linux v4.6
- Drop any reference to arm32
---
xen/arch/arm/arm64/Makefile | 1 +
xen/arch/arm/arm64/insn.c | 219 +++++++++++++++++++++++++++++++++++++++
xen/include/asm-arm/arm64/insn.h | 72 +++++++++++++
xen/include/asm-arm/insn.h | 20 ++++
4 files changed, 312 insertions(+)
create mode 100644 xen/arch/arm/arm64/insn.c
create mode 100644 xen/include/asm-arm/arm64/insn.h
create mode 100644 xen/include/asm-arm/insn.h
diff --git a/xen/arch/arm/arm64/Makefile b/xen/arch/arm/arm64/Makefile
index 39c6ac6..c1fa43f 100644
--- a/xen/arch/arm/arm64/Makefile
+++ b/xen/arch/arm/arm64/Makefile
@@ -5,6 +5,7 @@ obj-$(EARLY_PRINTK) += debug.o
obj-y += domctl.o
obj-y += domain.o
obj-y += entry.o
+obj-y += insn.o
obj-y += smpboot.o
obj-y += traps.o
obj-y += vfp.o
diff --git a/xen/arch/arm/arm64/insn.c b/xen/arch/arm/arm64/insn.c
new file mode 100644
index 0000000..12b4d96
--- /dev/null
+++ b/xen/arch/arm/arm64/insn.c
@@ -0,0 +1,219 @@
+/*
+ * Based on Linux v4.6 arch/arm64/kernel.ins.c
+ *
+ * Copyright (C) 2013 Huawei Ltd.
+ * Author: Jiang Liu <liuj97@xxxxxxxxx>
+ *
+ * Copyright (C) 2014-2016 Zi Shen Lim <zlim.lnx@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <xen/config.h>
+#include <xen/types.h>
+#include <xen/lib.h>
+#include <xen/errno.h>
+#include <xen/sizes.h>
+#include <xen/bitops.h>
+#include <asm/insn.h>
+#include <asm/arm64/insn.h>
+
+#define __kprobes
+#define pr_err(fmt, ...) printk(XENLOG_ERR fmt, ## __VA_ARGS__)
+
+bool aarch64_insn_is_branch_imm(u32 insn)
+{
+ return (aarch64_insn_is_b(insn) || aarch64_insn_is_bl(insn) ||
+ aarch64_insn_is_tbz(insn) || aarch64_insn_is_tbnz(insn) ||
+ aarch64_insn_is_cbz(insn) || aarch64_insn_is_cbnz(insn) ||
+ aarch64_insn_is_bcond(insn));
+}
+
+static int __kprobes aarch64_get_imm_shift_mask(enum aarch64_insn_imm_type
type,
+ u32 *maskp, int *shiftp)
+{
+ u32 mask;
+ int shift;
+
+ switch (type) {
+ case AARCH64_INSN_IMM_26:
+ mask = BIT(26) - 1;
+ shift = 0;
+ break;
+ case AARCH64_INSN_IMM_19:
+ mask = BIT(19) - 1;
+ shift = 5;
+ break;
+ case AARCH64_INSN_IMM_16:
+ mask = BIT(16) - 1;
+ shift = 5;
+ break;
+ case AARCH64_INSN_IMM_14:
+ mask = BIT(14) - 1;
+ shift = 5;
+ break;
+ case AARCH64_INSN_IMM_12:
+ mask = BIT(12) - 1;
+ shift = 10;
+ break;
+ case AARCH64_INSN_IMM_9:
+ mask = BIT(9) - 1;
+ shift = 12;
+ break;
+ case AARCH64_INSN_IMM_7:
+ mask = BIT(7) - 1;
+ shift = 15;
+ break;
+ case AARCH64_INSN_IMM_6:
+ case AARCH64_INSN_IMM_S:
+ mask = BIT(6) - 1;
+ shift = 10;
+ break;
+ case AARCH64_INSN_IMM_R:
+ mask = BIT(6) - 1;
+ shift = 16;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ *maskp = mask;
+ *shiftp = shift;
+
+ return 0;
+}
+
+#define ADR_IMM_HILOSPLIT 2
+#define ADR_IMM_SIZE SZ_2M
+#define ADR_IMM_LOMASK ((1 << ADR_IMM_HILOSPLIT) - 1)
+#define ADR_IMM_HIMASK ((ADR_IMM_SIZE >> ADR_IMM_HILOSPLIT) - 1)
+#define ADR_IMM_LOSHIFT 29
+#define ADR_IMM_HISHIFT 5
+
+u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn)
+{
+ u32 immlo, immhi, mask;
+ int shift;
+
+ switch (type) {
+ case AARCH64_INSN_IMM_ADR:
+ shift = 0;
+ immlo = (insn >> ADR_IMM_LOSHIFT) & ADR_IMM_LOMASK;
+ immhi = (insn >> ADR_IMM_HISHIFT) & ADR_IMM_HIMASK;
+ insn = (immhi << ADR_IMM_HILOSPLIT) | immlo;
+ mask = ADR_IMM_SIZE - 1;
+ break;
+ default:
+ if (aarch64_get_imm_shift_mask(type, &mask, &shift) < 0) {
+ pr_err("aarch64_insn_decode_immediate: unknown
immediate encoding %d\n",
+ type);
+ return 0;
+ }
+ }
+
+ return (insn >> shift) & mask;
+}
+
+u32 __kprobes aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
+ u32 insn, u64 imm)
+{
+ u32 immlo, immhi, mask;
+ int shift;
+
+ if (insn == AARCH64_BREAK_FAULT)
+ return AARCH64_BREAK_FAULT;
+
+ switch (type) {
+ case AARCH64_INSN_IMM_ADR:
+ shift = 0;
+ immlo = (imm & ADR_IMM_LOMASK) << ADR_IMM_LOSHIFT;
+ imm >>= ADR_IMM_HILOSPLIT;
+ immhi = (imm & ADR_IMM_HIMASK) << ADR_IMM_HISHIFT;
+ imm = immlo | immhi;
+ mask = ((ADR_IMM_LOMASK << ADR_IMM_LOSHIFT) |
+ (ADR_IMM_HIMASK << ADR_IMM_HISHIFT));
+ break;
+ default:
+ if (aarch64_get_imm_shift_mask(type, &mask, &shift) < 0) {
+ pr_err("aarch64_insn_encode_immediate: unknown
immediate encoding %d\n",
+ type);
+ return AARCH64_BREAK_FAULT;
+ }
+ }
+
+ /* Update the immediate field. */
+ insn &= ~(mask << shift);
+ insn |= (imm & mask) << shift;
+
+ return insn;
+}
+
+/*
+ * Decode the imm field of a branch, and return the byte offset as a
+ * signed value (so it can be used when computing a new branch
+ * target).
+ */
+s32 aarch64_get_branch_offset(u32 insn)
+{
+ s32 imm;
+
+ if (aarch64_insn_is_b(insn) || aarch64_insn_is_bl(insn)) {
+ imm = aarch64_insn_decode_immediate(AARCH64_INSN_IMM_26, insn);
+ return (imm << 6) >> 4;
+ }
+
+ if (aarch64_insn_is_cbz(insn) || aarch64_insn_is_cbnz(insn) ||
+ aarch64_insn_is_bcond(insn)) {
+ imm = aarch64_insn_decode_immediate(AARCH64_INSN_IMM_19, insn);
+ return (imm << 13) >> 11;
+ }
+
+ if (aarch64_insn_is_tbz(insn) || aarch64_insn_is_tbnz(insn)) {
+ imm = aarch64_insn_decode_immediate(AARCH64_INSN_IMM_14, insn);
+ return (imm << 18) >> 16;
+ }
+
+ /* Unhandled instruction */
+ BUG();
+}
+
+/*
+ * Encode the displacement of a branch in the imm field and return the
+ * updated instruction.
+ */
+u32 aarch64_set_branch_offset(u32 insn, s32 offset)
+{
+ if (aarch64_insn_is_b(insn) || aarch64_insn_is_bl(insn))
+ return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_26, insn,
+ offset >> 2);
+
+ if (aarch64_insn_is_cbz(insn) || aarch64_insn_is_cbnz(insn) ||
+ aarch64_insn_is_bcond(insn))
+ return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_19, insn,
+ offset >> 2);
+
+ if (aarch64_insn_is_tbz(insn) || aarch64_insn_is_tbnz(insn))
+ return aarch64_insn_encode_immediate(AARCH64_INSN_IMM_14, insn,
+ offset >> 2);
+
+ /* Unhandled instruction */
+ BUG();
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 8
+ * indent-tabs-mode: t
+ * End:
+ */
diff --git a/xen/include/asm-arm/arm64/insn.h b/xen/include/asm-arm/arm64/insn.h
new file mode 100644
index 0000000..cfcdbe9
--- /dev/null
+++ b/xen/include/asm-arm/arm64/insn.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2013 Huawei Ltd.
+ * Author: Jiang Liu <liuj97@xxxxxxxxx>
+ *
+ * Copyright (C) 2014 Zi Shen Lim <zlim.lnx@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __ARCH_ARM_ARM64_INSN
+#define __ARCH_ARM_ARM64_INSN
+
+#include <xen/config.h>
+#include <xen/types.h>
+#include <xen/stdbool.h>
+
+enum aarch64_insn_imm_type {
+ AARCH64_INSN_IMM_ADR,
+ AARCH64_INSN_IMM_26,
+ AARCH64_INSN_IMM_19,
+ AARCH64_INSN_IMM_16,
+ AARCH64_INSN_IMM_14,
+ AARCH64_INSN_IMM_12,
+ AARCH64_INSN_IMM_9,
+ AARCH64_INSN_IMM_7,
+ AARCH64_INSN_IMM_6,
+ AARCH64_INSN_IMM_S,
+ AARCH64_INSN_IMM_R,
+ AARCH64_INSN_IMM_MAX
+};
+
+#define __AARCH64_INSN_FUNCS(abbr, mask, val) \
+static always_inline bool_t aarch64_insn_is_##abbr(u32 code) \
+{ return (code & (mask)) == (val); } \
+static always_inline u32 aarch64_insn_get_##abbr##_value(void) \
+{ return (val); }
+
+__AARCH64_INSN_FUNCS(b, 0xFC000000, 0x14000000)
+__AARCH64_INSN_FUNCS(bl, 0xFC000000, 0x94000000)
+__AARCH64_INSN_FUNCS(cbz, 0x7F000000, 0x34000000)
+__AARCH64_INSN_FUNCS(cbnz, 0x7F000000, 0x35000000)
+__AARCH64_INSN_FUNCS(tbz, 0x7F000000, 0x36000000)
+__AARCH64_INSN_FUNCS(tbnz, 0x7F000000, 0x37000000)
+__AARCH64_INSN_FUNCS(bcond, 0xFF000010, 0x54000000)
+
+bool aarch64_insn_is_branch_imm(u32 insn);
+
+u64 aarch64_insn_decode_immediate(enum aarch64_insn_imm_type type, u32 insn);
+u32 aarch64_insn_encode_immediate(enum aarch64_insn_imm_type type,
+ u32 insn, u64 imm);
+
+s32 aarch64_get_branch_offset(u32 insn);
+u32 aarch64_set_branch_offset(u32 insn, s32 offset);
+
+#endif /* !__ARCH_ARM_ARM64_INSN */
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 8
+ * indent-tabs-mode: t
+ * End:
+ */
diff --git a/xen/include/asm-arm/insn.h b/xen/include/asm-arm/insn.h
new file mode 100644
index 0000000..a205ceb
--- /dev/null
+++ b/xen/include/asm-arm/insn.h
@@ -0,0 +1,20 @@
+#ifndef __ARCH_ARM_INSN
+#define __ARCH_ARM_INSN
+
+#include <xen/types.h>
+
+#if defined(CONFIG_ARM_64)
+# include <asm/arm64/insn.h>
+#else
+# error "unknown ARM variant"
+#endif
+
+#endif /* !__ARCH_ARM_INSN */
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 8
+ * indent-tabs-mode: t
+ * End:
+ */
--
1.9.1
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