From d52fec86a465355b379e839fa372ead0334d62e6 Mon Sep 17 00:00:00 2001
From: Huacai Chen <chenhuacai@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 1/8] LoongArch: Add HWCAP_LOONGARCH_CPUCFG to elf_hwcap

HWCAP_LOONGARCH_CPUCFG is missing in elf_hwcap, so add it for glibc's
later use.

Cc: stable@vger.kernel.org
Reported-by: Yinyu Cai <caiyinyu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/kernel/cpu-probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/cpu-probe.c b/arch/loongarch/kernel/cpu-probe.c
index 255a09876ef28..3a3fce2d78461 100644
--- a/arch/loongarch/kernel/cpu-probe.c
+++ b/arch/loongarch/kernel/cpu-probe.c
@@ -94,7 +94,7 @@ static void cpu_probe_common(struct cpuinfo_loongarch *c)
 	c->options = LOONGARCH_CPU_CPUCFG | LOONGARCH_CPU_CSR |
 		     LOONGARCH_CPU_TLB | LOONGARCH_CPU_VINT | LOONGARCH_CPU_WATCH;
 
-	elf_hwcap |= HWCAP_LOONGARCH_CRC32;
+	elf_hwcap = HWCAP_LOONGARCH_CPUCFG | HWCAP_LOONGARCH_CRC32;
 
 	config = read_cpucfg(LOONGARCH_CPUCFG1);
 	if (config & CPUCFG1_UAL) {

From 2959fce7fdb73fc784aefd58cc34b1ba700826aa Mon Sep 17 00:00:00 2001
From: Tiezhu Yang <yangtiezhu@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 2/8] LoongArch: Use common function sign_extend64()

There exists a common function sign_extend64() to sign extend a 64-bit
value using specified bit as sign-bit in include/linux/bitops.h, it is
more efficient, let us use it and remove the arch-specific sign_extend()
under arch/loongarch.

Suggested-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/inst.h   | 8 --------
 arch/loongarch/kernel/alternative.c | 6 +++---
 2 files changed, 3 insertions(+), 11 deletions(-)

diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index c00e1512d4fa3..6cd994d6d9d08 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -377,14 +377,6 @@ static inline bool unsigned_imm_check(unsigned long val, unsigned int bit)
 	return val < (1UL << bit);
 }
 
-static inline unsigned long sign_extend(unsigned long val, unsigned int idx)
-{
-	if (!is_imm_negative(val, idx + 1))
-		return ((1UL << idx) - 1) & val;
-	else
-		return ~((1UL << idx) - 1) | val;
-}
-
 #define DEF_EMIT_REG0I26_FORMAT(NAME, OP)				\
 static inline void emit_##NAME(union loongarch_instruction *insn,	\
 			       int offset)				\
diff --git a/arch/loongarch/kernel/alternative.c b/arch/loongarch/kernel/alternative.c
index c5aebeac960b6..4ad13847e9626 100644
--- a/arch/loongarch/kernel/alternative.c
+++ b/arch/loongarch/kernel/alternative.c
@@ -74,7 +74,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
 	switch (src->reg0i26_format.opcode) {
 	case b_op:
 	case bl_op:
-		jump_addr = cur_pc + sign_extend((si_h << 16 | si_l) << 2, 27);
+		jump_addr = cur_pc + sign_extend64((si_h << 16 | si_l) << 2, 27);
 		if (in_alt_jump(jump_addr, start, end))
 			return;
 		offset = jump_addr - pc;
@@ -93,7 +93,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
 		fallthrough;
 	case beqz_op:
 	case bnez_op:
-		jump_addr = cur_pc + sign_extend((si_h << 16 | si_l) << 2, 22);
+		jump_addr = cur_pc + sign_extend64((si_h << 16 | si_l) << 2, 22);
 		if (in_alt_jump(jump_addr, start, end))
 			return;
 		offset = jump_addr - pc;
@@ -112,7 +112,7 @@ static void __init_or_module recompute_jump(union loongarch_instruction *buf,
 	case bge_op:
 	case bltu_op:
 	case bgeu_op:
-		jump_addr = cur_pc + sign_extend(si << 2, 17);
+		jump_addr = cur_pc + sign_extend64(si << 2, 17);
 		if (in_alt_jump(jump_addr, start, end))
 			return;
 		offset = jump_addr - pc;

From 3200983fa8e2c8aa17ed911b617b4a248bcb1267 Mon Sep 17 00:00:00 2001
From: Youling Tang <tangyouling@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 3/8] LoongArch: Simplify larch_insn_gen_xxx implementation

Simplify larch_insn_gen_xxx implementation by reusing emit_xxx.

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/inst.h |  1 +
 arch/loongarch/kernel/inst.c      | 45 +++++--------------------------
 2 files changed, 8 insertions(+), 38 deletions(-)

diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index 6cd994d6d9d08..7eedd83fd0d72 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -393,6 +393,7 @@ static inline void emit_##NAME(union loongarch_instruction *insn,	\
 }
 
 DEF_EMIT_REG0I26_FORMAT(b, b_op)
+DEF_EMIT_REG0I26_FORMAT(bl, bl_op)
 
 #define DEF_EMIT_REG1I20_FORMAT(NAME, OP)				\
 static inline void emit_##NAME(union loongarch_instruction *insn,	\
diff --git a/arch/loongarch/kernel/inst.c b/arch/loongarch/kernel/inst.c
index 512579d79b221..badc590870423 100644
--- a/arch/loongarch/kernel/inst.c
+++ b/arch/loongarch/kernel/inst.c
@@ -58,7 +58,6 @@ u32 larch_insn_gen_nop(void)
 u32 larch_insn_gen_b(unsigned long pc, unsigned long dest)
 {
 	long offset = dest - pc;
-	unsigned int immediate_l, immediate_h;
 	union loongarch_instruction insn;
 
 	if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
@@ -66,15 +65,7 @@ u32 larch_insn_gen_b(unsigned long pc, unsigned long dest)
 		return INSN_BREAK;
 	}
 
-	offset >>= 2;
-
-	immediate_l = offset & 0xffff;
-	offset >>= 16;
-	immediate_h = offset & 0x3ff;
-
-	insn.reg0i26_format.opcode = b_op;
-	insn.reg0i26_format.immediate_l = immediate_l;
-	insn.reg0i26_format.immediate_h = immediate_h;
+	emit_b(&insn, offset >> 2);
 
 	return insn.word;
 }
@@ -82,7 +73,6 @@ u32 larch_insn_gen_b(unsigned long pc, unsigned long dest)
 u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
 {
 	long offset = dest - pc;
-	unsigned int immediate_l, immediate_h;
 	union loongarch_instruction insn;
 
 	if ((offset & 3) || offset < -SZ_128M || offset >= SZ_128M) {
@@ -90,15 +80,7 @@ u32 larch_insn_gen_bl(unsigned long pc, unsigned long dest)
 		return INSN_BREAK;
 	}
 
-	offset >>= 2;
-
-	immediate_l = offset & 0xffff;
-	offset >>= 16;
-	immediate_h = offset & 0x3ff;
-
-	insn.reg0i26_format.opcode = bl_op;
-	insn.reg0i26_format.immediate_l = immediate_l;
-	insn.reg0i26_format.immediate_h = immediate_h;
+	emit_bl(&insn, offset >> 2);
 
 	return insn.word;
 }
@@ -107,10 +89,7 @@ u32 larch_insn_gen_or(enum loongarch_gpr rd, enum loongarch_gpr rj, enum loongar
 {
 	union loongarch_instruction insn;
 
-	insn.reg3_format.opcode = or_op;
-	insn.reg3_format.rd = rd;
-	insn.reg3_format.rj = rj;
-	insn.reg3_format.rk = rk;
+	emit_or(&insn, rd, rj, rk);
 
 	return insn.word;
 }
@@ -124,9 +103,7 @@ u32 larch_insn_gen_lu12iw(enum loongarch_gpr rd, int imm)
 {
 	union loongarch_instruction insn;
 
-	insn.reg1i20_format.opcode = lu12iw_op;
-	insn.reg1i20_format.rd = rd;
-	insn.reg1i20_format.immediate = imm;
+	emit_lu12iw(&insn, rd, imm);
 
 	return insn.word;
 }
@@ -135,9 +112,7 @@ u32 larch_insn_gen_lu32id(enum loongarch_gpr rd, int imm)
 {
 	union loongarch_instruction insn;
 
-	insn.reg1i20_format.opcode = lu32id_op;
-	insn.reg1i20_format.rd = rd;
-	insn.reg1i20_format.immediate = imm;
+	emit_lu32id(&insn, rd, imm);
 
 	return insn.word;
 }
@@ -146,10 +121,7 @@ u32 larch_insn_gen_lu52id(enum loongarch_gpr rd, enum loongarch_gpr rj, int imm)
 {
 	union loongarch_instruction insn;
 
-	insn.reg2i12_format.opcode = lu52id_op;
-	insn.reg2i12_format.rd = rd;
-	insn.reg2i12_format.rj = rj;
-	insn.reg2i12_format.immediate = imm;
+	emit_lu52id(&insn, rd, rj, imm);
 
 	return insn.word;
 }
@@ -158,10 +130,7 @@ u32 larch_insn_gen_jirl(enum loongarch_gpr rd, enum loongarch_gpr rj, unsigned l
 {
 	union loongarch_instruction insn;
 
-	insn.reg2i16_format.opcode = jirl_op;
-	insn.reg2i16_format.rd = rd;
-	insn.reg2i16_format.rj = rj;
-	insn.reg2i16_format.immediate = (dest - pc) >> 2;
+	emit_jirl(&insn, rj, rd, (dest - pc) >> 2);
 
 	return insn.word;
 }

From e2f27392275c7ffceb4afac1567eb325722b9ae1 Mon Sep 17 00:00:00 2001
From: Jinyang He <hejinyang@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 4/8] LoongArch: Adjust PC value when unwind next frame in
 unwinder

When state->first is not set, the PC is a return address in the previous
frame. We need to adjust its value in case overflow to the next symbol.

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/kernel/unwind_prologue.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 0f8d1451ebb84..e98b00432c885 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -56,7 +56,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
 {
 	long frame_ra = -1;
 	unsigned long frame_size = 0;
-	unsigned long size, offset, pc = state->pc;
+	unsigned long size, offset, pc;
 	struct pt_regs *regs;
 	struct stack_info *info = &state->stack_info;
 	union loongarch_instruction *ip, *ip_end;
@@ -78,6 +78,11 @@ static bool unwind_by_prologue(struct unwind_state *state)
 		return true;
 	}
 
+	/*
+	 * When first is not set, the PC is a return address in the previous frame.
+	 * We need to adjust its value in case overflow to the next symbol.
+	 */
+	pc = state->pc - (state->first ? 0 : LOONGARCH_INSN_SIZE);
 	if (!kallsyms_lookup_size_offset(pc, &size, &offset))
 		return false;
 

From 429a9671f235c94fc4b5d6687308714b74adc820 Mon Sep 17 00:00:00 2001
From: Jinyang He <hejinyang@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 5/8] LoongArch: Get frame info in unwind_start() when regs is
 not available

At unwind_start(), it is better to get its frame info here rather than
get them outside, even we don't have 'regs'. In this way we can simply
use unwind_{start, next_frame, done} outside.

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/kernel/process.c         | 12 +++---------
 arch/loongarch/kernel/unwind_guess.c    |  6 ++++++
 arch/loongarch/kernel/unwind_prologue.c | 16 +++++++++++++---
 3 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/arch/loongarch/kernel/process.c b/arch/loongarch/kernel/process.c
index c583b1ef1f44c..edfd220a3737a 100644
--- a/arch/loongarch/kernel/process.c
+++ b/arch/loongarch/kernel/process.c
@@ -191,20 +191,14 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 
 unsigned long __get_wchan(struct task_struct *task)
 {
-	unsigned long pc;
+	unsigned long pc = 0;
 	struct unwind_state state;
 
 	if (!try_get_task_stack(task))
 		return 0;
 
-	unwind_start(&state, task, NULL);
-	state.sp = thread_saved_fp(task);
-	get_stack_info(state.sp, state.task, &state.stack_info);
-	state.pc = thread_saved_ra(task);
-#ifdef CONFIG_UNWINDER_PROLOGUE
-	state.type = UNWINDER_PROLOGUE;
-#endif
-	for (; !unwind_done(&state); unwind_next_frame(&state)) {
+	for (unwind_start(&state, task, NULL);
+	     !unwind_done(&state); unwind_next_frame(&state)) {
 		pc = unwind_get_return_address(&state);
 		if (!pc)
 			break;
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index e2d2e4f3001f4..9ef5f2a47f880 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -26,6 +26,12 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 	if (regs) {
 		state->sp = regs->regs[3];
 		state->pc = regs->csr_era;
+	} else if (task && task != current) {
+		state->sp = thread_saved_fp(task);
+		state->pc = thread_saved_ra(task);
+	} else {
+		state->sp = (unsigned long)__builtin_frame_address(0);
+		state->pc = (unsigned long)__builtin_return_address(0);
 	}
 
 	state->task = task;
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index e98b00432c885..613545ce6a976 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -146,12 +146,22 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 		    struct pt_regs *regs)
 {
 	memset(state, 0, sizeof(*state));
+	state->type = UNWINDER_PROLOGUE;
 
-	if (regs &&  __kernel_text_address(regs->csr_era)) {
-		state->pc = regs->csr_era;
+	if (regs) {
 		state->sp = regs->regs[3];
+		state->pc = regs->csr_era;
 		state->ra = regs->regs[1];
-		state->type = UNWINDER_PROLOGUE;
+		if (!__kernel_text_address(state->pc))
+			state->type = UNWINDER_GUESS;
+	} else if (task && task != current) {
+		state->sp = thread_saved_fp(task);
+		state->pc = thread_saved_ra(task);
+		state->ra = 0;
+	} else {
+		state->sp = (unsigned long)__builtin_frame_address(0);
+		state->pc = (unsigned long)__builtin_return_address(0);
+		state->ra = 0;
 	}
 
 	state->task = task;

From 5bb8d34449c4a2eb94d657b992170afafac274f9 Mon Sep 17 00:00:00 2001
From: Jinyang He <hejinyang@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 6/8] LoongArch: Use correct sp value to get graph addr in
 stack unwinders

The stack frame when function_graph enable like follows,

---------  <- function sp_on_entry
    |
    |
    |
 FAKE_RA   <- sp_on_entry - sizeof(pt_regs) + PT_R1
    |
---------  <- sp_on_entry - sizeof(pt_regs)

So if we want to get the &FAKE_RA we should get sp_on_entry first. In
the unwinder_prologue case, we can get the sp_on_entry as state->sp,
because we try to calculate each CFA and the ra saved address. But in
the unwinder_guess case, we cannot get it because we do not try to
calculate the CFA. Although LoongArch have not fixed frame, the $ra is
saved at CFA - 8 in most cases, we can try guess, too. As we store the
pc in state, we not need to dereference state->sp, too.

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/ftrace.h     |  2 --
 arch/loongarch/include/asm/unwind.h     | 10 ++++++++++
 arch/loongarch/kernel/unwind_guess.c    | 11 ++++-------
 arch/loongarch/kernel/unwind_prologue.c | 21 ++++++---------------
 4 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/arch/loongarch/include/asm/ftrace.h b/arch/loongarch/include/asm/ftrace.h
index 90f9d3399b2aa..3418d32d4fc7d 100644
--- a/arch/loongarch/include/asm/ftrace.h
+++ b/arch/loongarch/include/asm/ftrace.h
@@ -10,8 +10,6 @@
 #define FTRACE_REGS_PLT_IDX	1
 #define NR_FTRACE_PLTS		2
 
-#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
-
 #ifdef CONFIG_FUNCTION_TRACER
 
 #define MCOUNT_INSN_SIZE 4		/* sizeof mcount call */
diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index f2b52b9ea93d2..834ba6bd15d29 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -8,7 +8,9 @@
 #define _ASM_UNWIND_H
 
 #include <linux/sched.h>
+#include <linux/ftrace.h>
 
+#include <asm/ptrace.h>
 #include <asm/stacktrace.h>
 
 enum unwinder_type {
@@ -40,4 +42,12 @@ static inline bool unwind_error(struct unwind_state *state)
 	return state->error;
 }
 
+#define GRAPH_FAKE_OFFSET (sizeof(struct pt_regs) - offsetof(struct pt_regs, regs[1]))
+
+static inline unsigned long unwind_graph_addr(struct unwind_state *state,
+					unsigned long pc, unsigned long cfa)
+{
+	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
+				     pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
+}
 #endif /* _ASM_UNWIND_H */
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index 9ef5f2a47f880..e7e637bdba17e 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -11,10 +11,8 @@ unsigned long unwind_get_return_address(struct unwind_state *state)
 {
 	if (unwind_done(state))
 		return 0;
-	else if (state->first)
-		return state->pc;
 
-	return *(unsigned long *)(state->sp);
+	return state->pc;
 }
 EXPORT_SYMBOL_GPL(unwind_get_return_address);
 
@@ -36,7 +34,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 
 	state->task = task;
 	state->first = true;
-
+	state->pc = unwind_graph_addr(state, state->pc, state->sp);
 	get_stack_info(state->sp, state->task, &state->stack_info);
 
 	if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -60,9 +58,8 @@ bool unwind_next_frame(struct unwind_state *state)
 		     state->sp < info->end;
 		     state->sp += sizeof(unsigned long)) {
 			addr = *(unsigned long *)(state->sp);
-			state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-					addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
-			if (__kernel_text_address(addr))
+			state->pc = unwind_graph_addr(state, addr, state->sp + 8);
+			if (__kernel_text_address(state->pc))
 				return true;
 		}
 
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 613545ce6a976..463ba2391bdf4 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -21,16 +21,10 @@ static inline void unwind_state_fixup(struct unwind_state *state)
 
 unsigned long unwind_get_return_address(struct unwind_state *state)
 {
-
 	if (unwind_done(state))
 		return 0;
-	else if (state->type)
-		return state->pc;
-	else if (state->first)
-		return state->pc;
-
-	return *(unsigned long *)(state->sp);
 
+	return state->pc;
 }
 EXPORT_SYMBOL_GPL(unwind_get_return_address);
 
@@ -43,9 +37,8 @@ static bool unwind_by_guess(struct unwind_state *state)
 	     state->sp < info->end;
 	     state->sp += sizeof(unsigned long)) {
 		addr = *(unsigned long *)(state->sp);
-		state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-				addr, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
-		if (__kernel_text_address(addr))
+		state->pc = unwind_graph_addr(state, addr, state->sp + 8);
+		if (__kernel_text_address(state->pc))
 			return true;
 	}
 
@@ -166,7 +159,7 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
 
 	state->task = task;
 	state->first = true;
-
+	state->pc = unwind_graph_addr(state, state->pc, state->sp);
 	get_stack_info(state->sp, state->task, &state->stack_info);
 
 	if (!unwind_done(state) && !__kernel_text_address(state->pc))
@@ -193,8 +186,7 @@ bool unwind_next_frame(struct unwind_state *state)
 
 		case UNWINDER_PROLOGUE:
 			if (unwind_by_prologue(state)) {
-				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-						state->pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
+				state->pc = unwind_graph_addr(state, state->pc, state->sp);
 				return true;
 			}
 
@@ -209,8 +201,7 @@ bool unwind_next_frame(struct unwind_state *state)
 				state->first = true;
 				state->ra = regs->regs[1];
 				state->sp = regs->regs[3];
-				state->pc = ftrace_graph_ret_addr(state->task, &state->graph_idx,
-						pc, (unsigned long *)(state->sp - GRAPH_FAKE_OFFSET));
+				state->pc = pc;
 				get_stack_info(state->sp, state->task, info);
 
 				return true;

From c5ac25e0d78a6f63446b8fef4d8630ccd7a2663d Mon Sep 17 00:00:00 2001
From: Jinyang He <hejinyang@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 7/8] LoongArch: Strip guess unwinder out from prologue
 unwinder

The prolugue unwinder rely on symbol info. When PC is not in kernel text
address, it cannot find relative symbol info and it will be broken. The
guess unwinder will be used in this case. And the guess unwinder code in
prolugue unwinder is redundant. Strip it out and set the unwinder type
in unwind_state. Make guess_unwinder::unwind_next_frame() as default way
when other unwinders cannot unwind in some extreme case.

Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/unwind.h     |  29 +++++
 arch/loongarch/kernel/Makefile          |   2 +-
 arch/loongarch/kernel/traps.c           |   3 -
 arch/loongarch/kernel/unwind.c          |  32 +++++
 arch/loongarch/kernel/unwind_guess.c    |  52 +-------
 arch/loongarch/kernel/unwind_prologue.c | 157 ++++++++++--------------
 6 files changed, 129 insertions(+), 146 deletions(-)
 create mode 100644 arch/loongarch/kernel/unwind.c

diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index 834ba6bd15d29..36584b95ef8b6 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -27,6 +27,8 @@ struct unwind_state {
 	unsigned long sp, pc, ra;
 };
 
+bool default_next_frame(struct unwind_state *state);
+
 void unwind_start(struct unwind_state *state,
 		  struct task_struct *task, struct pt_regs *regs);
 bool unwind_next_frame(struct unwind_state *state);
@@ -50,4 +52,31 @@ static inline unsigned long unwind_graph_addr(struct unwind_state *state,
 	return ftrace_graph_ret_addr(state->task, &state->graph_idx,
 				     pc, (unsigned long *)(cfa - GRAPH_FAKE_OFFSET));
 }
+
+static __always_inline void __unwind_start(struct unwind_state *state,
+					struct task_struct *task, struct pt_regs *regs)
+{
+	memset(state, 0, sizeof(*state));
+	if (regs) {
+		state->sp = regs->regs[3];
+		state->pc = regs->csr_era;
+		state->ra = regs->regs[1];
+	} else if (task && task != current) {
+		state->sp = thread_saved_fp(task);
+		state->pc = thread_saved_ra(task);
+		state->ra = 0;
+	} else {
+		state->sp = (unsigned long)__builtin_frame_address(0);
+		state->pc = (unsigned long)__builtin_return_address(0);
+		state->ra = 0;
+	}
+	state->task = task;
+	get_stack_info(state->sp, state->task, &state->stack_info);
+	state->pc = unwind_graph_addr(state, state->pc, state->sp);
+}
+
+static __always_inline unsigned long __unwind_get_return_address(struct unwind_state *state)
+{
+	return unwind_done(state) ? 0 : state->pc;
+}
 #endif /* _ASM_UNWIND_H */
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index fcaa024a685ec..c8cfbd562921d 100644
--- a/arch/loongarch/kernel/Makefile
+++ b/arch/loongarch/kernel/Makefile
@@ -8,7 +8,7 @@ extra-y		:= vmlinux.lds
 obj-y		+= head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
 		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
 		   elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \
-		   alternative.o unaligned.o
+		   alternative.o unaligned.o unwind.o
 
 obj-$(CONFIG_ACPI)		+= acpi.o
 obj-$(CONFIG_EFI) 		+= efi.o
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c
index 7ea62faeeadb5..c38a146a973b4 100644
--- a/arch/loongarch/kernel/traps.c
+++ b/arch/loongarch/kernel/traps.c
@@ -72,9 +72,6 @@ static void show_backtrace(struct task_struct *task, const struct pt_regs *regs,
 	if (!task)
 		task = current;
 
-	if (user_mode(regs))
-		state.type = UNWINDER_GUESS;
-
 	printk("%sCall Trace:", loglvl);
 	for (unwind_start(&state, task, pregs);
 	      !unwind_done(&state); unwind_next_frame(&state)) {
diff --git a/arch/loongarch/kernel/unwind.c b/arch/loongarch/kernel/unwind.c
new file mode 100644
index 0000000000000..a463d6961344c
--- /dev/null
+++ b/arch/loongarch/kernel/unwind.c
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022-2023 Loongson Technology Corporation Limited
+ */
+#include <linux/kernel.h>
+#include <linux/ftrace.h>
+
+#include <asm/unwind.h>
+
+bool default_next_frame(struct unwind_state *state)
+{
+	struct stack_info *info = &state->stack_info;
+	unsigned long addr;
+
+	if (unwind_done(state))
+		return false;
+
+	do {
+		for (state->sp += sizeof(unsigned long);
+		     state->sp < info->end; state->sp += sizeof(unsigned long)) {
+			addr = *(unsigned long *)(state->sp);
+			state->pc = unwind_graph_addr(state, addr, state->sp + 8);
+			if (__kernel_text_address(state->pc))
+				return true;
+		}
+
+		state->sp = info->next_sp;
+
+	} while (!get_stack_info(state->sp, state->task, info));
+
+	return false;
+}
diff --git a/arch/loongarch/kernel/unwind_guess.c b/arch/loongarch/kernel/unwind_guess.c
index e7e637bdba17e..98379b7d41475 100644
--- a/arch/loongarch/kernel/unwind_guess.c
+++ b/arch/loongarch/kernel/unwind_guess.c
@@ -2,41 +2,18 @@
 /*
  * Copyright (C) 2022 Loongson Technology Corporation Limited
  */
-#include <linux/kernel.h>
-#include <linux/ftrace.h>
-
 #include <asm/unwind.h>
 
 unsigned long unwind_get_return_address(struct unwind_state *state)
 {
-	if (unwind_done(state))
-		return 0;
-
-	return state->pc;
+	return __unwind_get_return_address(state);
 }
 EXPORT_SYMBOL_GPL(unwind_get_return_address);
 
 void unwind_start(struct unwind_state *state, struct task_struct *task,
 		    struct pt_regs *regs)
 {
-	memset(state, 0, sizeof(*state));
-
-	if (regs) {
-		state->sp = regs->regs[3];
-		state->pc = regs->csr_era;
-	} else if (task && task != current) {
-		state->sp = thread_saved_fp(task);
-		state->pc = thread_saved_ra(task);
-	} else {
-		state->sp = (unsigned long)__builtin_frame_address(0);
-		state->pc = (unsigned long)__builtin_return_address(0);
-	}
-
-	state->task = task;
-	state->first = true;
-	state->pc = unwind_graph_addr(state, state->pc, state->sp);
-	get_stack_info(state->sp, state->task, &state->stack_info);
-
+	__unwind_start(state, task, regs);
 	if (!unwind_done(state) && !__kernel_text_address(state->pc))
 		unwind_next_frame(state);
 }
@@ -44,29 +21,6 @@ EXPORT_SYMBOL_GPL(unwind_start);
 
 bool unwind_next_frame(struct unwind_state *state)
 {
-	struct stack_info *info = &state->stack_info;
-	unsigned long addr;
-
-	if (unwind_done(state))
-		return false;
-
-	if (state->first)
-		state->first = false;
-
-	do {
-		for (state->sp += sizeof(unsigned long);
-		     state->sp < info->end;
-		     state->sp += sizeof(unsigned long)) {
-			addr = *(unsigned long *)(state->sp);
-			state->pc = unwind_graph_addr(state, addr, state->sp + 8);
-			if (__kernel_text_address(state->pc))
-				return true;
-		}
-
-		state->sp = info->next_sp;
-
-	} while (!get_stack_info(state->sp, state->task, info));
-
-	return false;
+	return default_next_frame(state);
 }
 EXPORT_SYMBOL_GPL(unwind_next_frame);
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index 463ba2391bdf4..dfc352dba7465 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -19,32 +19,14 @@ static inline void unwind_state_fixup(struct unwind_state *state)
 #endif
 }
 
-unsigned long unwind_get_return_address(struct unwind_state *state)
-{
-	if (unwind_done(state))
-		return 0;
-
-	return state->pc;
-}
-EXPORT_SYMBOL_GPL(unwind_get_return_address);
-
-static bool unwind_by_guess(struct unwind_state *state)
-{
-	struct stack_info *info = &state->stack_info;
-	unsigned long addr;
-
-	for (state->sp += sizeof(unsigned long);
-	     state->sp < info->end;
-	     state->sp += sizeof(unsigned long)) {
-		addr = *(unsigned long *)(state->sp);
-		state->pc = unwind_graph_addr(state, addr, state->sp + 8);
-		if (__kernel_text_address(state->pc))
-			return true;
-	}
-
-	return false;
-}
-
+/*
+ * LoongArch function prologue is like follows,
+ *     [instructions not use stack var]
+ *     addi.d sp, sp, -imm
+ *     st.d   xx, sp, offset <- save callee saved regs and
+ *     st.d   yy, sp, offset    save ra if function is nest.
+ *     [others instructions]
+ */
 static bool unwind_by_prologue(struct unwind_state *state)
 {
 	long frame_ra = -1;
@@ -91,6 +73,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
 		ip++;
 	}
 
+	/*
+	 * Can't find stack alloc action, PC may be in a leaf function. Only the
+	 * first being true is reasonable, otherwise indicate analysis is broken.
+	 */
 	if (!frame_size) {
 		if (state->first)
 			goto first;
@@ -108,6 +94,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
 		ip++;
 	}
 
+	/* Can't find save $ra action, PC may be in a leaf function, too. */
 	if (frame_ra < 0) {
 		if (state->first) {
 			state->sp = state->sp + frame_size;
@@ -116,96 +103,48 @@ static bool unwind_by_prologue(struct unwind_state *state)
 		return false;
 	}
 
-	if (state->first)
-		state->first = false;
-
 	state->pc = *(unsigned long *)(state->sp + frame_ra);
 	state->sp = state->sp + frame_size;
 	goto out;
 
 first:
-	state->first = false;
-	if (state->pc == state->ra)
-		return false;
-
 	state->pc = state->ra;
 
 out:
+	state->first = false;
 	unwind_state_fixup(state);
 	return !!__kernel_text_address(state->pc);
 }
 
-void unwind_start(struct unwind_state *state, struct task_struct *task,
-		    struct pt_regs *regs)
-{
-	memset(state, 0, sizeof(*state));
-	state->type = UNWINDER_PROLOGUE;
-
-	if (regs) {
-		state->sp = regs->regs[3];
-		state->pc = regs->csr_era;
-		state->ra = regs->regs[1];
-		if (!__kernel_text_address(state->pc))
-			state->type = UNWINDER_GUESS;
-	} else if (task && task != current) {
-		state->sp = thread_saved_fp(task);
-		state->pc = thread_saved_ra(task);
-		state->ra = 0;
-	} else {
-		state->sp = (unsigned long)__builtin_frame_address(0);
-		state->pc = (unsigned long)__builtin_return_address(0);
-		state->ra = 0;
-	}
-
-	state->task = task;
-	state->first = true;
-	state->pc = unwind_graph_addr(state, state->pc, state->sp);
-	get_stack_info(state->sp, state->task, &state->stack_info);
-
-	if (!unwind_done(state) && !__kernel_text_address(state->pc))
-		unwind_next_frame(state);
-}
-EXPORT_SYMBOL_GPL(unwind_start);
-
-bool unwind_next_frame(struct unwind_state *state)
+static bool next_frame(struct unwind_state *state)
 {
-	struct stack_info *info = &state->stack_info;
-	struct pt_regs *regs;
 	unsigned long pc;
+	struct pt_regs *regs;
+	struct stack_info *info = &state->stack_info;
 
 	if (unwind_done(state))
 		return false;
 
 	do {
-		switch (state->type) {
-		case UNWINDER_GUESS:
-			state->first = false;
-			if (unwind_by_guess(state))
-				return true;
-			break;
-
-		case UNWINDER_PROLOGUE:
-			if (unwind_by_prologue(state)) {
-				state->pc = unwind_graph_addr(state, state->pc, state->sp);
-				return true;
-			}
+		if (unwind_by_prologue(state)) {
+			state->pc = unwind_graph_addr(state, state->pc, state->sp);
+			return true;
+		}
 
-			if (info->type == STACK_TYPE_IRQ &&
-				info->end == state->sp) {
-				regs = (struct pt_regs *)info->next_sp;
-				pc = regs->csr_era;
+		if (info->type == STACK_TYPE_IRQ && info->end == state->sp) {
+			regs = (struct pt_regs *)info->next_sp;
+			pc = regs->csr_era;
 
-				if (user_mode(regs) || !__kernel_text_address(pc))
-					return false;
+			if (user_mode(regs) || !__kernel_text_address(pc))
+				return false;
 
-				state->first = true;
-				state->ra = regs->regs[1];
-				state->sp = regs->regs[3];
-				state->pc = pc;
-				get_stack_info(state->sp, state->task, info);
+			state->first = true;
+			state->pc = pc;
+			state->ra = regs->regs[1];
+			state->sp = regs->regs[3];
+			get_stack_info(state->sp, state->task, info);
 
-				return true;
-			}
+			return true;
 		}
 
 		state->sp = info->next_sp;
@@ -214,4 +153,36 @@ bool unwind_next_frame(struct unwind_state *state)
 
 	return false;
 }
+
+unsigned long unwind_get_return_address(struct unwind_state *state)
+{
+	return __unwind_get_return_address(state);
+}
+EXPORT_SYMBOL_GPL(unwind_get_return_address);
+
+void unwind_start(struct unwind_state *state, struct task_struct *task,
+		    struct pt_regs *regs)
+{
+	__unwind_start(state, task, regs);
+	state->type = UNWINDER_PROLOGUE;
+	state->first = true;
+
+	/*
+	 * The current PC is not kernel text address, we cannot find its
+	 * relative symbol. Thus, prologue analysis will be broken. Luckily,
+	 * we can use the default_next_frame().
+	 */
+	if (!__kernel_text_address(state->pc)) {
+		state->type = UNWINDER_GUESS;
+		if (!unwind_done(state))
+			unwind_next_frame(state);
+	}
+}
+EXPORT_SYMBOL_GPL(unwind_start);
+
+bool unwind_next_frame(struct unwind_state *state)
+{
+	return state->type == UNWINDER_PROLOGUE ?
+			next_frame(state) : default_next_frame(state);
+}
 EXPORT_SYMBOL_GPL(unwind_next_frame);

From dc74a9e8a8c57966a563ab078ba91c8b2c0d0a72 Mon Sep 17 00:00:00 2001
From: Jinyang He <hejinyang@loongson.cn>
Date: Tue, 17 Jan 2023 11:42:16 +0800
Subject: [PATCH 8/8] LoongArch: Add generic ex-handler unwind in prologue
 unwinder

When exception is triggered, code flow go handle_\exception in some
cases. One of stackframe in this case as follows,

high -> +-------+
        | REGS  |  <- a pt_regs
        |       |
        |       |  <- ex trigger
        | REGS  |  <- ex pt_regs   <-+
        |       |                    |
        |       |                    |
low  -> +-------+           ->unwind-+

When unwinder unwinds to handler_\exception it cannot go on prologue
analysis. Because it is an asynchronous code flow, we should get the
next frame PC from regs->csr_era rather than regs->regs[1]. At init time
we copy the handlers to eentry and also copy them to NUMA-affine memory
named pcpu_handlers if NUMA is enabled. Thus, unwinder cannot unwind
normally. To solve this, we try to give some hints in handler_\exception
and fixup unwinders in unwind_next_frame().

Reported-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
 arch/loongarch/include/asm/unwind.h     |   2 +-
 arch/loongarch/kernel/genex.S           |   3 +
 arch/loongarch/kernel/unwind_prologue.c | 101 +++++++++++++++++++++---
 arch/loongarch/mm/tlb.c                 |   2 +-
 4 files changed, 93 insertions(+), 15 deletions(-)

diff --git a/arch/loongarch/include/asm/unwind.h b/arch/loongarch/include/asm/unwind.h
index 36584b95ef8b6..b9dce87afd2e0 100644
--- a/arch/loongarch/include/asm/unwind.h
+++ b/arch/loongarch/include/asm/unwind.h
@@ -22,7 +22,7 @@ struct unwind_state {
 	char type; /* UNWINDER_XXX */
 	struct stack_info stack_info;
 	struct task_struct *task;
-	bool first, error, is_ftrace;
+	bool first, error, reset;
 	int graph_idx;
 	unsigned long sp, pc, ra;
 };
diff --git a/arch/loongarch/kernel/genex.S b/arch/loongarch/kernel/genex.S
index 75e5be807a0d5..7e5c293ed89f7 100644
--- a/arch/loongarch/kernel/genex.S
+++ b/arch/loongarch/kernel/genex.S
@@ -67,14 +67,17 @@ SYM_FUNC_END(except_vec_cex)
 	.macro	BUILD_HANDLER exception handler prep
 	.align	5
 	SYM_FUNC_START(handle_\exception)
+	666:
 	BACKUP_T0T1
 	SAVE_ALL
 	build_prep_\prep
 	move	a0, sp
 	la.abs	t0, do_\handler
 	jirl	ra, t0, 0
+	668:
 	RESTORE_ALL_AND_RET
 	SYM_FUNC_END(handle_\exception)
+	SYM_DATA(unwind_hint_\exception, .word 668b - 666b)
 	.endm
 
 	BUILD_HANDLER ade ade badv
diff --git a/arch/loongarch/kernel/unwind_prologue.c b/arch/loongarch/kernel/unwind_prologue.c
index dfc352dba7465..9095fde8e55d5 100644
--- a/arch/loongarch/kernel/unwind_prologue.c
+++ b/arch/loongarch/kernel/unwind_prologue.c
@@ -2,23 +2,103 @@
 /*
  * Copyright (C) 2022 Loongson Technology Corporation Limited
  */
+#include <linux/cpumask.h>
 #include <linux/ftrace.h>
 #include <linux/kallsyms.h>
 
 #include <asm/inst.h>
+#include <asm/loongson.h>
 #include <asm/ptrace.h>
+#include <asm/setup.h>
 #include <asm/unwind.h>
 
-static inline void unwind_state_fixup(struct unwind_state *state)
+extern const int unwind_hint_ade;
+extern const int unwind_hint_ale;
+extern const int unwind_hint_bp;
+extern const int unwind_hint_fpe;
+extern const int unwind_hint_fpu;
+extern const int unwind_hint_lsx;
+extern const int unwind_hint_lasx;
+extern const int unwind_hint_lbt;
+extern const int unwind_hint_ri;
+extern const int unwind_hint_watch;
+extern unsigned long eentry;
+#ifdef CONFIG_NUMA
+extern unsigned long pcpu_handlers[NR_CPUS];
+#endif
+
+static inline bool scan_handlers(unsigned long entry_offset)
 {
-#ifdef CONFIG_DYNAMIC_FTRACE
-	static unsigned long ftrace = (unsigned long)ftrace_call + 4;
+	int idx, offset;
+
+	if (entry_offset >= EXCCODE_INT_START * VECSIZE)
+		return false;
+
+	idx = entry_offset / VECSIZE;
+	offset = entry_offset % VECSIZE;
+	switch (idx) {
+	case EXCCODE_ADE:
+		return offset == unwind_hint_ade;
+	case EXCCODE_ALE:
+		return offset == unwind_hint_ale;
+	case EXCCODE_BP:
+		return offset == unwind_hint_bp;
+	case EXCCODE_FPE:
+		return offset == unwind_hint_fpe;
+	case EXCCODE_FPDIS:
+		return offset == unwind_hint_fpu;
+	case EXCCODE_LSXDIS:
+		return offset == unwind_hint_lsx;
+	case EXCCODE_LASXDIS:
+		return offset == unwind_hint_lasx;
+	case EXCCODE_BTDIS:
+		return offset == unwind_hint_lbt;
+	case EXCCODE_INE:
+		return offset == unwind_hint_ri;
+	case EXCCODE_WATCH:
+		return offset == unwind_hint_watch;
+	default:
+		return false;
+	}
+}
+
+static inline bool fix_exception(unsigned long pc)
+{
+#ifdef CONFIG_NUMA
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		if (!pcpu_handlers[cpu])
+			continue;
+		if (scan_handlers(pc - pcpu_handlers[cpu]))
+			return true;
+	}
+#endif
+	return scan_handlers(pc - eentry);
+}
 
-	if (state->pc == ftrace)
-		state->is_ftrace = true;
+/*
+ * As we meet ftrace_regs_entry, reset first flag like first doing
+ * tracing. Prologue analysis will stop soon because PC is at entry.
+ */
+static inline bool fix_ftrace(unsigned long pc)
+{
+#ifdef CONFIG_DYNAMIC_FTRACE
+	return pc == (unsigned long)ftrace_call + LOONGARCH_INSN_SIZE;
+#else
+	return false;
 #endif
 }
 
+static inline bool unwind_state_fixup(struct unwind_state *state)
+{
+	if (!fix_exception(state->pc) && !fix_ftrace(state->pc))
+		return false;
+
+	state->reset = true;
+	return true;
+}
+
 /*
  * LoongArch function prologue is like follows,
  *     [instructions not use stack var]
@@ -39,14 +119,10 @@ static bool unwind_by_prologue(struct unwind_state *state)
 	if (state->sp >= info->end || state->sp < info->begin)
 		return false;
 
-	if (state->is_ftrace) {
-		/*
-		 * As we meet ftrace_regs_entry, reset first flag like first doing
-		 * tracing. Prologue analysis will stop soon because PC is at entry.
-		 */
+	if (state->reset) {
 		regs = (struct pt_regs *)state->sp;
 		state->first = true;
-		state->is_ftrace = false;
+		state->reset = false;
 		state->pc = regs->csr_era;
 		state->ra = regs->regs[1];
 		state->sp = regs->regs[3];
@@ -112,8 +188,7 @@ static bool unwind_by_prologue(struct unwind_state *state)
 
 out:
 	state->first = false;
-	unwind_state_fixup(state);
-	return !!__kernel_text_address(state->pc);
+	return unwind_state_fixup(state) || __kernel_text_address(state->pc);
 }
 
 static bool next_frame(struct unwind_state *state)
diff --git a/arch/loongarch/mm/tlb.c b/arch/loongarch/mm/tlb.c
index da3681f131c8d..8bad6b0cff59b 100644
--- a/arch/loongarch/mm/tlb.c
+++ b/arch/loongarch/mm/tlb.c
@@ -251,7 +251,7 @@ static void output_pgtable_bits_defines(void)
 }
 
 #ifdef CONFIG_NUMA
-static unsigned long pcpu_handlers[NR_CPUS];
+unsigned long pcpu_handlers[NR_CPUS];
 #endif
 extern long exception_handlers[VECSIZE * 128 / sizeof(long)];