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Date: Mon, 24 Oct 2022 15:04:37 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Arnd Bergmann <arnd@...db.de>, Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev, linux-arch@...r.kernel.org,
Xuefeng Li <lixuefeng@...ngson.cn>,
Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
linux-kernel@...r.kernel.org, Huacai Chen <chenhuacai@...ngson.cn>,
Jun Yi <yijun@...ngson.cn>
Subject: [PATCH 1/2] LoongArch: Add alternative runtime patching mechanism
Introduce the "alternative" mechanism from ARM64 and x86 for LoongArch
to apply runtime patching. The main purpose of this patch is to provide
a framework. In future we can use this mechanism (i.e., the ALTERNATIVE
and ALTERNATIVE_2 macros) to optimize hotspot functions according to cpu
features.
Signed-off-by: Jun Yi <yijun@...ngson.cn>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
arch/loongarch/include/asm/alternative-asm.h | 82 ++++++
arch/loongarch/include/asm/alternative.h | 176 ++++++++++++
arch/loongarch/include/asm/bugs.h | 15 ++
arch/loongarch/include/asm/inst.h | 10 +
arch/loongarch/kernel/Makefile | 2 +-
arch/loongarch/kernel/alternative.c | 266 +++++++++++++++++++
arch/loongarch/kernel/module.c | 16 ++
arch/loongarch/kernel/setup.c | 7 +
arch/loongarch/kernel/vmlinux.lds.S | 12 +
9 files changed, 585 insertions(+), 1 deletion(-)
create mode 100644 arch/loongarch/include/asm/alternative-asm.h
create mode 100644 arch/loongarch/include/asm/alternative.h
create mode 100644 arch/loongarch/include/asm/bugs.h
create mode 100644 arch/loongarch/kernel/alternative.c
diff --git a/arch/loongarch/include/asm/alternative-asm.h b/arch/loongarch/include/asm/alternative-asm.h
new file mode 100644
index 000000000000..f0f32ace29b1
--- /dev/null
+++ b/arch/loongarch/include/asm/alternative-asm.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALTERNATIVE_ASM_H
+#define _ASM_ALTERNATIVE_ASM_H
+
+#ifdef __ASSEMBLY__
+
+#include <asm/asm.h>
+
+/*
+ * Issue one struct alt_instr descriptor entry (need to put it into
+ * the section .altinstructions, see below). This entry contains
+ * enough information for the alternatives patching code to patch an
+ * instruction. See apply_alternatives().
+ */
+.macro altinstruction_entry orig alt feature orig_len alt_len
+ .long \orig - .
+ .long \alt - .
+ .2byte \feature
+ .byte \orig_len
+ .byte \alt_len
+.endm
+
+/*
+ * Define an alternative between two instructions. If @feature is
+ * present, early code in apply_alternatives() replaces @oldinstr with
+ * @newinstr. ".fill" directive takes care of proper instruction padding
+ * in case @newinstr is longer than @oldinstr.
+ */
+.macro ALTERNATIVE oldinstr, newinstr, feature
+140 :
+ \oldinstr
+141 :
+ .fill - (((144f-143f)-(141b-140b)) > 0) * ((144f-143f)-(141b-140b)) / 4, 4, 0x03400000
+142 :
+
+ .pushsection .altinstructions, "a"
+ altinstruction_entry 140b, 143f, \feature, 142b-140b, 144f-143f
+ .popsection
+
+ .subsection 1
+143 :
+ \newinstr
+144 :
+ .previous
+.endm
+
+#define old_len (141b-140b)
+#define new_len1 (144f-143f)
+#define new_len2 (145f-144f)
+
+#define alt_max_short(a, b) ((a) ^ (((a) ^ (b)) & -(-((a) < (b)))))
+
+/*
+ * Same as ALTERNATIVE macro above but for two alternatives. If CPU
+ * has @feature1, it replaces @oldinstr with @newinstr1. If CPU has
+ * @feature2, it replaces @oldinstr with @feature2.
+ */
+.macro ALTERNATIVE_2 oldinstr, newinstr1, feature1, newinstr2, feature2
+140 :
+ \oldinstr
+141 :
+ .fill - ((alt_max_short(new_len1, new_len2) - (old_len)) > 0) * \
+ (alt_max_short(new_len1, new_len2) - (old_len)) / 4, 4, 0x03400000
+142 :
+
+ .pushsection .altinstructions, "a"
+ altinstruction_entry 140b, 143f, \feature1, 142b-140b, 144f-143f, 142b-141b
+ altinstruction_entry 140b, 144f, \feature2, 142b-140b, 145f-144f, 142b-141b
+ .popsection
+
+ .subsection 1
+143 :
+ \newinstr1
+144 :
+ \newinstr2
+145 :
+ .previous
+.endm
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_ALTERNATIVE_ASM_H */
diff --git a/arch/loongarch/include/asm/alternative.h b/arch/loongarch/include/asm/alternative.h
new file mode 100644
index 000000000000..b4fe66c7067e
--- /dev/null
+++ b/arch/loongarch/include/asm/alternative.h
@@ -0,0 +1,176 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALTERNATIVE_H
+#define _ASM_ALTERNATIVE_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/types.h>
+#include <linux/stddef.h>
+#include <linux/stringify.h>
+#include <asm/asm.h>
+
+struct alt_instr {
+ s32 instr_offset; /* offset to original instruction */
+ s32 replace_offset; /* offset to replacement instruction */
+ u16 feature; /* feature bit set for replacement */
+ u8 instrlen; /* length of original instruction */
+ u8 replacementlen; /* length of new instruction */
+} __packed;
+
+/*
+ * Debug flag that can be tested to see whether alternative
+ * instructions were patched in already:
+ */
+extern int alternatives_patched;
+extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
+
+extern void alternative_instructions(void);
+extern void apply_alternatives(struct alt_instr *start, struct alt_instr *end);
+
+#define b_replacement(num) "664"#num
+#define e_replacement(num) "665"#num
+
+#define alt_end_marker "663"
+#define alt_slen "662b-661b"
+#define alt_total_slen alt_end_marker"b-661b"
+#define alt_rlen(num) e_replacement(num)"f-"b_replacement(num)"f"
+
+#define __OLDINSTR(oldinstr, num) \
+ "661:\n\t" oldinstr "\n662:\n" \
+ ".fill -(((" alt_rlen(num) ")-(" alt_slen ")) > 0) * " \
+ "((" alt_rlen(num) ")-(" alt_slen ")) / 4, 4, 0x03400000\n"
+
+#define OLDINSTR(oldinstr, num) \
+ __OLDINSTR(oldinstr, num) \
+ alt_end_marker ":\n"
+
+#define alt_max_short(a, b) "((" a ") ^ (((" a ") ^ (" b ")) & -(-((" a ") < (" b ")))))"
+
+/*
+ * Pad the second replacement alternative with additional NOPs if it is
+ * additionally longer than the first replacement alternative.
+ */
+#define OLDINSTR_2(oldinstr, num1, num2) \
+ "661:\n\t" oldinstr "\n662:\n" \
+ ".fill -((" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) > 0) * " \
+ "(" alt_max_short(alt_rlen(num1), alt_rlen(num2)) " - (" alt_slen ")) / 4, " \
+ "4, 0x03400000\n" \
+ alt_end_marker ":\n"
+
+#define ALTINSTR_ENTRY(feature, num) \
+ " .long 661b - .\n" /* label */ \
+ " .long " b_replacement(num)"f - .\n" /* new instruction */ \
+ " .2byte " __stringify(feature) "\n" /* feature bit */ \
+ " .byte " alt_total_slen "\n" /* source len */ \
+ " .byte " alt_rlen(num) "\n" /* replacement len */
+
+#define ALTINSTR_REPLACEMENT(newinstr, feature, num) /* replacement */ \
+ b_replacement(num)":\n\t" newinstr "\n" e_replacement(num) ":\n\t"
+
+/* alternative assembly primitive: */
+#define ALTERNATIVE(oldinstr, newinstr, feature) \
+ OLDINSTR(oldinstr, 1) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feature, 1) \
+ ".popsection\n" \
+ ".subsection 1\n" \
+ ALTINSTR_REPLACEMENT(newinstr, feature, 1) \
+ ".previous\n"
+
+#define ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2)\
+ OLDINSTR_2(oldinstr, 1, 2) \
+ ".pushsection .altinstructions,\"a\"\n" \
+ ALTINSTR_ENTRY(feature1, 1) \
+ ALTINSTR_ENTRY(feature2, 2) \
+ ".popsection\n" \
+ ".subsection 1\n" \
+ ALTINSTR_REPLACEMENT(newinstr1, feature1, 1) \
+ ALTINSTR_REPLACEMENT(newinstr2, feature2, 2) \
+ ".previous\n"
+
+/*
+ * Alternative instructions for different CPU types or capabilities.
+ *
+ * This allows to use optimized instructions even on generic binary
+ * kernels.
+ *
+ * length of oldinstr must be longer or equal the length of newinstr
+ * It can be padded with nops as needed.
+ *
+ * For non barrier like inlines please define new variants
+ * without volatile and memory clobber.
+ */
+#define alternative(oldinstr, newinstr, feature) \
+ (asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) : : : "memory"))
+
+#define alternative_2(oldinstr, newinstr1, feature1, newinstr2, feature2) \
+ (asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, newinstr2, feature2) ::: "memory"))
+
+/*
+ * Alternative inline assembly with input.
+ *
+ * Pecularities:
+ * No memory clobber here.
+ * Argument numbers start with 1.
+ * Best is to use constraints that are fixed size (like (%1) ... "r")
+ * If you use variable sized constraints like "m" or "g" in the
+ * replacement make sure to pad to the worst case length.
+ * Leaving an unused argument 0 to keep API compatibility.
+ */
+#define alternative_input(oldinstr, newinstr, feature, input...) \
+ (asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
+ : : "i" (0), ## input))
+
+/*
+ * This is similar to alternative_input. But it has two features and
+ * respective instructions.
+ *
+ * If CPU has feature2, newinstr2 is used.
+ * Otherwise, if CPU has feature1, newinstr1 is used.
+ * Otherwise, oldinstr is used.
+ */
+#define alternative_input_2(oldinstr, newinstr1, feature1, newinstr2, \
+ feature2, input...) \
+ (asm volatile(ALTERNATIVE_2(oldinstr, newinstr1, feature1, \
+ newinstr2, feature2) \
+ : : "i" (0), ## input))
+
+/* Like alternative_input, but with a single output argument */
+#define alternative_io(oldinstr, newinstr, feature, output, input...) \
+ (asm volatile (ALTERNATIVE(oldinstr, newinstr, feature) \
+ : output : "i" (0), ## input))
+
+/* Like alternative_io, but for replacing a direct call with another one. */
+#define alternative_call(oldfunc, newfunc, feature, output, input...) \
+ (asm volatile (ALTERNATIVE("call %P[old]", "call %P[new]", feature) \
+ : output : [old] "i" (oldfunc), [new] "i" (newfunc), ## input))
+
+/*
+ * Like alternative_call, but there are two features and respective functions.
+ * If CPU has feature2, function2 is used.
+ * Otherwise, if CPU has feature1, function1 is used.
+ * Otherwise, old function is used.
+ */
+#define alternative_call_2(oldfunc, newfunc1, feature1, newfunc2, feature2, \
+ output, input...) \
+ (asm volatile (ALTERNATIVE_2("call %P[old]", "call %P[new1]", feature1,\
+ "call %P[new2]", feature2) \
+ : output, ASM_CALL_CONSTRAINT \
+ : [old] "i" (oldfunc), [new1] "i" (newfunc1), \
+ [new2] "i" (newfunc2), ## input))
+
+/*
+ * use this macro(s) if you need more than one output parameter
+ * in alternative_io
+ */
+#define ASM_OUTPUT2(a...) a
+
+/*
+ * use this macro if you need clobbers but no inputs in
+ * alternative_{input,io,call}()
+ */
+#define ASM_NO_INPUT_CLOBBER(clbr...) "i" (0) : clbr
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_ALTERNATIVE_H */
diff --git a/arch/loongarch/include/asm/bugs.h b/arch/loongarch/include/asm/bugs.h
new file mode 100644
index 000000000000..651fffe1f743
--- /dev/null
+++ b/arch/loongarch/include/asm/bugs.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * This is included by init/main.c to check for architecture-dependent bugs.
+ *
+ * Copyright (C) 2020-2021 Loongson Technology Corporation Limited
+ */
+#ifndef _ASM_BUGS_H
+#define _ASM_BUGS_H
+
+#include <asm/cpu.h>
+#include <asm/cpu-info.h>
+
+extern void check_bugs(void);
+
+#endif /* _ASM_BUGS_H */
diff --git a/arch/loongarch/include/asm/inst.h b/arch/loongarch/include/asm/inst.h
index 889d6c9fc2b6..bd4c116aa73d 100644
--- a/arch/loongarch/include/asm/inst.h
+++ b/arch/loongarch/include/asm/inst.h
@@ -8,6 +8,7 @@
#include <linux/types.h>
#include <asm/asm.h>
+#define INSN_NOP 0x03400000
#define INSN_BREAK 0x002a0000
#define ADDR_IMMMASK_LU52ID 0xFFF0000000000000
@@ -28,6 +29,7 @@ enum reg0i26_op {
enum reg1i20_op {
lu12iw_op = 0x0a,
lu32id_op = 0x0b,
+ pcaddi_op = 0x0c,
pcaddu12i_op = 0x0e,
pcaddu18i_op = 0x0f,
};
@@ -35,6 +37,8 @@ enum reg1i20_op {
enum reg1i21_op {
beqz_op = 0x10,
bnez_op = 0x11,
+ bceqz_op = 0x12,
+ bcnez_op = 0x12,
};
enum reg2_op {
@@ -315,6 +319,12 @@ static inline bool is_imm_negative(unsigned long val, unsigned int bit)
return val & (1UL << (bit - 1));
}
+static inline bool is_pc_ins(union loongarch_instruction *ip)
+{
+ return ip->reg1i20_format.opcode >= pcaddi_op &&
+ ip->reg1i20_format.opcode <= pcaddu18i_op;
+}
+
static inline bool is_branch_ins(union loongarch_instruction *ip)
{
return ip->reg1i21_format.opcode >= beqz_op &&
diff --git a/arch/loongarch/kernel/Makefile b/arch/loongarch/kernel/Makefile
index 2ad2555b53ea..86744531b100 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 \
- unaligned.o
+ alternative.o unaligned.o
obj-$(CONFIG_ACPI) += acpi.o
obj-$(CONFIG_EFI) += efi.o
diff --git a/arch/loongarch/kernel/alternative.c b/arch/loongarch/kernel/alternative.c
new file mode 100644
index 000000000000..43434150b853
--- /dev/null
+++ b/arch/loongarch/kernel/alternative.c
@@ -0,0 +1,263 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <asm/alternative.h>
+#include <asm/cacheflush.h>
+#include <asm/inst.h>
+#include <asm/sections.h>
+
+int __read_mostly alternatives_patched;
+
+EXPORT_SYMBOL_GPL(alternatives_patched);
+
+#define MAX_PATCH_SIZE (((u8)(-1)) / LOONGARCH_INSN_SIZE)
+
+static int __initdata_or_module debug_alternative;
+
+static int __init debug_alt(char *str)
+{
+ debug_alternative = 1;
+ return 1;
+}
+__setup("debug-alternative", debug_alt);
+
+#define DPRINTK(fmt, args...) \
+do { \
+ if (debug_alternative) \
+ printk(KERN_DEBUG "%s: " fmt "\n", __func__, ##args); \
+} while (0)
+
+#define DUMP_WORDS(buf, count, fmt, args...) \
+do { \
+ if (unlikely(debug_alternative)) { \
+ int _j; \
+ union loongarch_instruction *_buf = buf; \
+ \
+ if (!(count)) \
+ break; \
+ \
+ printk(KERN_DEBUG fmt, ##args); \
+ for (_j = 0; _j < count - 1; _j++) \
+ printk(KERN_CONT "<%08x> ", _buf[_j].word); \
+ printk(KERN_CONT "<%08x>\n", _buf[_j].word); \
+ } \
+} while (0)
+
+#define __SIGNEX(X, SIDX) ((X) >= (1 << SIDX) ? ~((1 << SIDX) - 1) | (X) : (X))
+#define SIGNEX16(X) __SIGNEX(((unsigned long)(X)), 15)
+#define SIGNEX20(X) __SIGNEX(((unsigned long)(X)), 19)
+#define SIGNEX21(X) __SIGNEX(((unsigned long)(X)), 20)
+#define SIGNEX26(X) __SIGNEX(((unsigned long)(X)), 25)
+
+static inline unsigned long bs_dest_16(unsigned long now, unsigned int si)
+{
+ return now + (SIGNEX16(si) << 2);
+}
+
+static inline unsigned long bs_dest_21(unsigned long now, unsigned int h, unsigned int l)
+{
+ return now + (SIGNEX21(h << 16 | l) << 2);
+}
+
+static inline unsigned long bs_dest_26(unsigned long now, unsigned int h, unsigned int l)
+{
+ return now + (SIGNEX26(h << 16 | l) << 2);
+}
+
+/* Use this to add nops to a buffer, then text_poke the whole buffer. */
+static void __init_or_module add_nops(union loongarch_instruction *insn, int count)
+{
+ while (count--) {
+ insn->word = INSN_NOP;
+ insn++;
+ }
+}
+
+/* Is the jump addr in local .altinstructions */
+static inline bool in_alt_jump(unsigned long jump, void *start, void *end)
+{
+ return jump >= (unsigned long)start && jump < (unsigned long)end;
+}
+
+static void __init_or_module recompute_jump(union loongarch_instruction *buf,
+ union loongarch_instruction *dest, union loongarch_instruction *src,
+ void *start, void *end)
+{
+ unsigned int si, si_l, si_h;
+ unsigned long cur_pc, jump_addr, pc;
+ long offset;
+
+ cur_pc = (unsigned long)src;
+ pc = (unsigned long)dest;
+
+ si_l = src->reg0i26_format.immediate_l;
+ si_h = src->reg0i26_format.immediate_h;
+ switch (src->reg0i26_format.opcode) {
+ case b_op:
+ case bl_op:
+ jump_addr = bs_dest_26(cur_pc, si_h, si_l);
+ if (in_alt_jump(jump_addr, start, end))
+ return;
+ offset = jump_addr - pc;
+ BUG_ON(offset < -SZ_128M || offset >= SZ_128M);
+ offset >>= 2;
+ buf->reg0i26_format.immediate_h = offset >> 16;
+ buf->reg0i26_format.immediate_l = offset;
+ return;
+ }
+
+ si_l = src->reg1i21_format.immediate_l;
+ si_h = src->reg1i21_format.immediate_h;
+ switch (src->reg1i21_format.opcode) {
+ case beqz_op:
+ case bnez_op:
+ case bceqz_op:
+ jump_addr = bs_dest_21(cur_pc, si_h, si_l);
+ if (in_alt_jump(jump_addr, start, end))
+ return;
+ offset = jump_addr - pc;
+ BUG_ON(offset < -SZ_4M || offset >= SZ_4M);
+ offset >>= 2;
+ buf->reg1i21_format.immediate_h = offset >> 16;
+ buf->reg1i21_format.immediate_l = offset;
+ return;
+ }
+
+ si = src->reg2i16_format.immediate;
+ switch (src->reg2i16_format.opcode) {
+ case beq_op:
+ case bne_op:
+ case blt_op:
+ case bge_op:
+ case bltu_op:
+ case bgeu_op:
+ jump_addr = bs_dest_16(cur_pc, si);
+ if (in_alt_jump(jump_addr, start, end))
+ return;
+ offset = jump_addr - pc;
+ BUG_ON(offset < -SZ_128K || offset >= SZ_128K);
+ offset >>= 2;
+ buf->reg2i16_format.immediate = offset;
+ return;
+ }
+}
+
+static int __init_or_module copy_alt_insns(union loongarch_instruction *buf,
+ union loongarch_instruction *dest, union loongarch_instruction *src, int nr)
+{
+ int i;
+
+ for (i = 0; i < nr; i++) {
+ buf[i].word = src[i].word;
+
+ if (is_branch_ins(&src[i]) &&
+ src[i].reg2i16_format.opcode != jirl_op) {
+ recompute_jump(&buf[i], &dest[i], &src[i], src, src + nr);
+ } else if (is_pc_ins(&src[i])) {
+ pr_err("Not support pcrel instruction at present!");
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * text_poke_early - Update instructions on a live kernel at boot time
+ *
+ * When you use this code to patch more than one byte of an instruction
+ * you need to make sure that other CPUs cannot execute this code in parallel.
+ * Also no thread must be currently preempted in the middle of these
+ * instructions. And on the local CPU you need to be protected again NMI or MCE
+ * handlers seeing an inconsistent instruction while you patch.
+ */
+static void *__init_or_module text_poke_early(union loongarch_instruction *insn,
+ union loongarch_instruction *buf, unsigned int nr)
+{
+ int i;
+ unsigned long flags;
+
+ local_irq_save(flags);
+
+ for (i = 0; i < nr; i++)
+ insn[i].word = buf[i].word;
+
+ local_irq_restore(flags);
+
+ wbflush();
+ flush_icache_range((unsigned long)insn, (unsigned long)(insn + nr));
+
+ return insn;
+}
+
+/*
+ * Replace instructions with better alternatives for this CPU type. This runs
+ * before SMP is initialized to avoid SMP problems with self modifying code.
+ * This implies that asymmetric systems where APs have less capabilities than
+ * the boot processor are not handled. Tough. Make sure you disable such
+ * features by hand.
+ */
+void __init_or_module apply_alternatives(struct alt_instr *start, struct alt_instr *end)
+{
+ struct alt_instr *a;
+ unsigned int nr_instr, nr_repl, nr_insnbuf;
+ union loongarch_instruction *instr, *replacement;
+ union loongarch_instruction insnbuf[MAX_PATCH_SIZE];
+
+ DPRINTK("alt table %px, -> %px", start, end);
+ /*
+ * The scan order should be from start to end. A later scanned
+ * alternative code can overwrite previously scanned alternative code.
+ * Some kernel functions (e.g. memcpy, memset, etc) use this order to
+ * patch code.
+ *
+ * So be careful if you want to change the scan order to any other
+ * order.
+ */
+ for (a = start; a < end; a++) {
+ nr_insnbuf = 0;
+
+ instr = (void *)&a->instr_offset + a->instr_offset;
+ replacement = (void *)&a->replace_offset + a->replace_offset;
+
+ BUG_ON(a->instrlen > sizeof(insnbuf));
+ BUG_ON(a->instrlen & 0x3);
+ BUG_ON(a->replacementlen & 0x3);
+
+ nr_instr = a->instrlen / LOONGARCH_INSN_SIZE;
+ nr_repl = a->replacementlen / LOONGARCH_INSN_SIZE;
+
+ if (!cpu_has(a->feature)) {
+ DPRINTK("feat not exist: %d, old: (%px len: %d), repl: (%px, len: %d)",
+ a->feature, instr, a->instrlen,
+ replacement, a->replacementlen);
+
+ continue;
+ }
+
+ DPRINTK("feat: %d, old: (%px len: %d), repl: (%px, len: %d)",
+ a->feature, instr, a->instrlen,
+ replacement, a->replacementlen);
+
+ DUMP_WORDS(instr, nr_instr, "%px: old_insn: ", instr);
+ DUMP_WORDS(replacement, nr_repl, "%px: rpl_insn: ", replacement);
+
+ copy_alt_insns(insnbuf, instr, replacement, nr_repl);
+ nr_insnbuf = nr_repl;
+
+ if (nr_instr > nr_repl) {
+ add_nops(insnbuf + nr_repl, nr_instr - nr_repl);
+ nr_insnbuf += nr_instr - nr_repl;
+ }
+ DUMP_WORDS(insnbuf, nr_insnbuf, "%px: final_insn: ", instr);
+
+ text_poke_early(instr, insnbuf, nr_insnbuf);
+ }
+}
+
+void __init alternative_instructions(void)
+{
+ apply_alternatives(__alt_instructions, __alt_instructions_end);
+
+ alternatives_patched = 1;
+}
diff --git a/arch/loongarch/kernel/module.c b/arch/loongarch/kernel/module.c
index 097595b2fc14..669e750917a3 100644
--- a/arch/loongarch/kernel/module.c
+++ b/arch/loongarch/kernel/module.c
@@ -17,6 +17,7 @@
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <asm/alternative.h>
static int rela_stack_push(s64 stack_value, s64 *rela_stack, size_t *rela_stack_top)
{
@@ -456,3 +457,18 @@ void *module_alloc(unsigned long size)
return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
GFP_KERNEL, PAGE_KERNEL, 0, NUMA_NO_NODE, __builtin_return_address(0));
}
+
+int module_finalize(const Elf_Ehdr *hdr,
+ const Elf_Shdr *sechdrs,
+ struct module *mod)
+{
+ const Elf_Shdr *s, *se;
+ const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+ for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) {
+ if (!strcmp(".altinstructions", secstrs + s->sh_name))
+ apply_alternatives((void *)s->sh_addr, (void *)s->sh_addr + s->sh_size);
+ }
+
+ return 0;
+}
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 1eb63fa9bc81..96b6cb5db004 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -31,7 +31,9 @@
#include <linux/swiotlb.h>
#include <asm/addrspace.h>
+#include <asm/alternative.h>
#include <asm/bootinfo.h>
+#include <asm/bugs.h>
#include <asm/cache.h>
#include <asm/cpu.h>
#include <asm/dma.h>
@@ -80,6 +82,11 @@ const char *get_system_type(void)
return "generic-loongson-machine";
}
+void __init check_bugs(void)
+{
+ alternative_instructions();
+}
+
static const char *dmi_string_parse(const struct dmi_header *dm, u8 s)
{
const u8 *bp = ((u8 *) dm) + dm->length;
diff --git a/arch/loongarch/kernel/vmlinux.lds.S b/arch/loongarch/kernel/vmlinux.lds.S
index efecda0c2361..733b16e8d55d 100644
--- a/arch/loongarch/kernel/vmlinux.lds.S
+++ b/arch/loongarch/kernel/vmlinux.lds.S
@@ -54,6 +54,18 @@ SECTIONS
. = ALIGN(PECOFF_SEGMENT_ALIGN);
_etext = .;
+ /*
+ * struct alt_inst entries. From the header (alternative.h):
+ * "Alternative instructions for different CPU types or capabilities"
+ * Think locking instructions on spinlocks.
+ */
+ . = ALIGN(4);
+ .altinstructions : AT(ADDR(.altinstructions) - LOAD_OFFSET) {
+ __alt_instructions = .;
+ *(.altinstructions)
+ __alt_instructions_end = .;
+ }
+
.got : ALIGN(16) { *(.got) }
.plt : ALIGN(16) { *(.plt) }
.got.plt : ALIGN(16) { *(.got.plt) }
--
2.31.1
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