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Message-Id: <1668751514-2998-2-git-send-email-yangtiezhu@loongson.cn>
Date: Fri, 18 Nov 2022 14:05:11 +0800
From: Tiezhu Yang <yangtiezhu@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>,
WANG Xuerui <kernel@...0n.name>,
Masami Hiramatsu <mhiramat@...nel.org>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: [PATCH v4 1/4] LoongArch: Simulate branch and PC instructions
According to LoongArch Reference Manual, simulate branch and
PC instructions, this is preparation for later patch.
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#branch-instructions
Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_pcaddi_pcaddu121_pcaddu18l_pcalau12i
Co-developed-by: Jinyang He <hejinyang@...ngson.cn>
Signed-off-by: Jinyang He <hejinyang@...ngson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@...ngson.cn>
---
arch/loongarch/include/asm/inst.h | 12 ++++
arch/loongarch/include/asm/ptrace.h | 1 +
arch/loongarch/kernel/inst.c | 123 ++++++++++++++++++++++++++++++++++++
3 files changed, 136 insertions(+)
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index a529137..dea85e7 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -7,6 +7,7 @@
#include <linux/types.h>
#include <asm/asm.h>
+#include <asm/ptrace.h>
#define INSN_NOP 0x03400000
#define INSN_BREAK 0x002a0000
@@ -30,6 +31,7 @@ enum reg1i20_op {
lu12iw_op = 0x0a,
lu32id_op = 0x0b,
pcaddi_op = 0x0c,
+ pcalau12i_op = 0x0d,
pcaddu12i_op = 0x0e,
pcaddu18i_op = 0x0f,
};
@@ -352,6 +354,16 @@ static inline bool is_stack_alloc_ins(union loongarch_instruction *ip)
u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm);
u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm);
u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned long pc, unsigned long dest);
+void simu_branch(struct pt_regs *regs, union loongarch_instruction insn);
+void simu_pc(struct pt_regs *regs, union loongarch_instruction insn);
+
+static inline unsigned long sign_extended(unsigned long val, unsigned int idx)
+{
+ if (val & (1UL << idx))
+ return ~((1UL << (idx + 1)) - 1) | val;
+ else
+ return ((1UL << (idx + 1)) - 1) & val;
+}
static inline bool signed_imm_check(long val, unsigned int bit)
{
diff --git a/arch/loongarch/include/asm/ptrace.h b/arch/loongarch/include/asm/ptrace.h
index 59c4608..58596c4 100644
--- a/arch/loongarch/include/asm/ptrace.h
+++ b/arch/loongarch/include/asm/ptrace.h
@@ -6,6 +6,7 @@
#define _ASM_PTRACE_H
#include <asm/page.h>
+#include <asm/irqflags.h>
#include <asm/thread_info.h>
#include <uapi/asm/ptrace.h>
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index b1df0ec..1da681e 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -38,3 +38,126 @@ u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned l
return insn.word;
}
+
+void simu_branch(struct pt_regs *regs, union loongarch_instruction insn)
+{
+ unsigned int imm, imm_l, imm_h, rd, rj;
+ unsigned long pc = regs->csr_era;
+
+ if (pc & 3) {
+ pr_warn("%s: invalid pc 0x%lx\n", __func__, pc);
+ return;
+ }
+
+ imm_l = insn.reg0i26_format.immediate_l;
+ imm_h = insn.reg0i26_format.immediate_h;
+ switch (insn.reg0i26_format.opcode) {
+ case b_op:
+ regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 27);
+ return;
+ case bl_op:
+ regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 27);
+ regs->regs[1] = pc + LOONGARCH_INSN_SIZE;
+ return;
+ }
+
+ imm_l = insn.reg1i21_format.immediate_l;
+ imm_h = insn.reg1i21_format.immediate_h;
+ rj = insn.reg1i21_format.rj;
+ switch (insn.reg1i21_format.opcode) {
+ case beqz_op:
+ if (regs->regs[rj] == 0)
+ regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 22);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ return;
+ case bnez_op:
+ if (regs->regs[rj] != 0)
+ regs->csr_era = pc + sign_extended((imm_h << 16 | imm_l) << 2, 22);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ return;
+ }
+
+ imm = insn.reg2i16_format.immediate;
+ rj = insn.reg2i16_format.rj;
+ rd = insn.reg2i16_format.rd;
+ switch (insn.reg2i16_format.opcode) {
+ case beq_op:
+ if (regs->regs[rj] == regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case bne_op:
+ if (regs->regs[rj] != regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case blt_op:
+ if ((long)regs->regs[rj] < (long)regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case bge_op:
+ if ((long)regs->regs[rj] >= (long)regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case bltu_op:
+ if (regs->regs[rj] < regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case bgeu_op:
+ if (regs->regs[rj] >= regs->regs[rd])
+ regs->csr_era = pc + sign_extended(imm << 2, 17);
+ else
+ regs->csr_era = pc + LOONGARCH_INSN_SIZE;
+ break;
+ case jirl_op:
+ regs->csr_era = regs->regs[rj] + sign_extended(imm << 2, 17);
+ regs->regs[rd] = pc + LOONGARCH_INSN_SIZE;
+ break;
+ default:
+ pr_info("%s: unknown opcode\n", __func__);
+ return;
+ }
+}
+
+void simu_pc(struct pt_regs *regs, union loongarch_instruction insn)
+{
+ unsigned long pc = regs->csr_era;
+ unsigned int rd = insn.reg1i20_format.rd;
+ unsigned int imm = insn.reg1i20_format.immediate;
+
+ if (pc & 3) {
+ pr_warn("%s: invalid pc 0x%lx\n", __func__, pc);
+ return;
+ }
+
+ switch (insn.reg1i20_format.opcode) {
+ case pcaddi_op:
+ regs->regs[rd] = pc + sign_extended(imm << 2, 21);
+ break;
+ case pcaddu12i_op:
+ regs->regs[rd] = pc + sign_extended(imm << 12, 31);
+ break;
+ case pcaddu18i_op:
+ regs->regs[rd] = pc + sign_extended(imm << 18, 37);
+ break;
+ case pcalau12i_op:
+ regs->regs[rd] = pc + sign_extended(imm << 12, 31);
+ regs->regs[rd] &= ~((1 << 12) - 1);
+ break;
+ default:
+ pr_info("%s: unknown opcode\n", __func__);
+ return;
+ }
+
+ regs->csr_era += LOONGARCH_INSN_SIZE;
+}
--
2.1.0
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