From 23fa18eaa71266feff7ba8d83022d9e1cc83c65a Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Fri, 10 May 2024 07:42:03 +0000
Subject: [PATCH] disable pwm7
---
kernel/arch/arm64/kernel/ftrace.c | 263 ++++++++++++++++++++++++++++++----------------------
1 files changed, 152 insertions(+), 111 deletions(-)
diff --git a/kernel/arch/arm64/kernel/ftrace.c b/kernel/arch/arm64/kernel/ftrace.c
index b661839..402a24f 100644
--- a/kernel/arch/arm64/kernel/ftrace.c
+++ b/kernel/arch/arm64/kernel/ftrace.c
@@ -1,12 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0-only
/*
* arch/arm64/kernel/ftrace.c
*
* Copyright (C) 2013 Linaro Limited
* Author: AKASHI Takahiro <takahiro.akashi@linaro.org>
- *
- * 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.
*/
#include <linux/ftrace.h>
@@ -65,6 +62,80 @@
return ftrace_modify_code(pc, 0, new, false);
}
+static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
+{
+#ifdef CONFIG_ARM64_MODULE_PLTS
+ struct plt_entry *plt = mod->arch.ftrace_trampolines;
+
+ if (addr == FTRACE_ADDR)
+ return &plt[FTRACE_PLT_IDX];
+ if (addr == FTRACE_REGS_ADDR &&
+ IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
+ return &plt[FTRACE_REGS_PLT_IDX];
+#endif
+ return NULL;
+}
+
+/*
+ * Find the address the callsite must branch to in order to reach '*addr'.
+ *
+ * Due to the limited range of 'BL' instructions, modules may be placed too far
+ * away to branch directly and must use a PLT.
+ *
+ * Returns true when '*addr' contains a reachable target address, or has been
+ * modified to contain a PLT address. Returns false otherwise.
+ */
+static bool ftrace_find_callable_addr(struct dyn_ftrace *rec,
+ struct module *mod,
+ unsigned long *addr)
+{
+ unsigned long pc = rec->ip;
+ long offset = (long)*addr - (long)pc;
+ struct plt_entry *plt;
+
+ /*
+ * When the target is within range of the 'BL' instruction, use 'addr'
+ * as-is and branch to that directly.
+ */
+ if (offset >= -SZ_128M && offset < SZ_128M)
+ return true;
+
+ /*
+ * When the target is outside of the range of a 'BL' instruction, we
+ * must use a PLT to reach it. We can only place PLTs for modules, and
+ * only when module PLT support is built-in.
+ */
+ if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
+ return false;
+
+ /*
+ * 'mod' is only set at module load time, but if we end up
+ * dealing with an out-of-range condition, we can assume it
+ * is due to a module being loaded far away from the kernel.
+ *
+ * NOTE: __module_text_address() must be called with preemption
+ * disabled, but we can rely on ftrace_lock to ensure that 'mod'
+ * retains its validity throughout the remainder of this code.
+ */
+ if (!mod) {
+ preempt_disable();
+ mod = __module_text_address(pc);
+ preempt_enable();
+ }
+
+ if (WARN_ON(!mod))
+ return false;
+
+ plt = get_ftrace_plt(mod, *addr);
+ if (!plt) {
+ pr_err("ftrace: no module PLT for %ps\n", (void *)*addr);
+ return false;
+ }
+
+ *addr = (unsigned long)plt;
+ return true;
+}
+
/*
* Turn on the call to ftrace_caller() in instrumented function
*/
@@ -72,75 +143,69 @@
{
unsigned long pc = rec->ip;
u32 old, new;
- long offset = (long)pc - (long)addr;
- if (offset < -SZ_128M || offset >= SZ_128M) {
-#ifdef CONFIG_ARM64_MODULE_PLTS
- struct plt_entry trampoline, *dst;
- struct module *mod;
-
- /*
- * On kernels that support module PLTs, the offset between the
- * branch instruction and its target may legally exceed the
- * range of an ordinary relative 'bl' opcode. In this case, we
- * need to branch via a trampoline in the module.
- *
- * NOTE: __module_text_address() must be called with preemption
- * disabled, but we can rely on ftrace_lock to ensure that 'mod'
- * retains its validity throughout the remainder of this code.
- */
- preempt_disable();
- mod = __module_text_address(pc);
- preempt_enable();
-
- if (WARN_ON(!mod))
- return -EINVAL;
-
- /*
- * There is only one ftrace trampoline per module. For now,
- * this is not a problem since on arm64, all dynamic ftrace
- * invocations are routed via ftrace_caller(). This will need
- * to be revisited if support for multiple ftrace entry points
- * is added in the future, but for now, the pr_err() below
- * deals with a theoretical issue only.
- */
- dst = mod->arch.ftrace_trampoline;
- trampoline = get_plt_entry(addr);
- if (!plt_entries_equal(dst, &trampoline)) {
- if (!plt_entries_equal(dst, &(struct plt_entry){})) {
- pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n");
- return -EINVAL;
- }
-
- /* point the trampoline to our ftrace entry point */
- module_disable_ro(mod);
- *dst = trampoline;
- module_enable_ro(mod, true);
-
- /*
- * Ensure updated trampoline is visible to instruction
- * fetch before we patch in the branch. Although the
- * architecture doesn't require an IPI in this case,
- * Neoverse-N1 erratum #1542419 does require one
- * if the TLB maintenance in module_enable_ro() is
- * skipped due to rodata_enabled. It doesn't seem worth
- * it to make it conditional given that this is
- * certainly not a fast-path.
- */
- flush_icache_range((unsigned long)&dst[0],
- (unsigned long)&dst[1]);
- }
- addr = (unsigned long)dst;
-#else /* CONFIG_ARM64_MODULE_PLTS */
+ if (!ftrace_find_callable_addr(rec, NULL, &addr))
return -EINVAL;
-#endif /* CONFIG_ARM64_MODULE_PLTS */
- }
old = aarch64_insn_gen_nop();
new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
return ftrace_modify_code(pc, old, new, true);
}
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
+ unsigned long addr)
+{
+ unsigned long pc = rec->ip;
+ u32 old, new;
+
+ if (!ftrace_find_callable_addr(rec, NULL, &old_addr))
+ return -EINVAL;
+ if (!ftrace_find_callable_addr(rec, NULL, &addr))
+ return -EINVAL;
+
+ old = aarch64_insn_gen_branch_imm(pc, old_addr,
+ AARCH64_INSN_BRANCH_LINK);
+ new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
+
+ return ftrace_modify_code(pc, old, new, true);
+}
+
+/*
+ * The compiler has inserted two NOPs before the regular function prologue.
+ * All instrumented functions follow the AAPCS, so x0-x8 and x19-x30 are live,
+ * and x9-x18 are free for our use.
+ *
+ * At runtime we want to be able to swing a single NOP <-> BL to enable or
+ * disable the ftrace call. The BL requires us to save the original LR value,
+ * so here we insert a <MOV X9, LR> over the first NOP so the instructions
+ * before the regular prologue are:
+ *
+ * | Compiled | Disabled | Enabled |
+ * +----------+------------+------------+
+ * | NOP | MOV X9, LR | MOV X9, LR |
+ * | NOP | NOP | BL <entry> |
+ *
+ * The LR value will be recovered by ftrace_regs_entry, and restored into LR
+ * before returning to the regular function prologue. When a function is not
+ * being traced, the MOV is not harmful given x9 is not live per the AAPCS.
+ *
+ * Note: ftrace_process_locs() has pre-adjusted rec->ip to be the address of
+ * the BL.
+ */
+int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
+{
+ unsigned long pc = rec->ip - AARCH64_INSN_SIZE;
+ u32 old, new;
+
+ old = aarch64_insn_gen_nop();
+ new = aarch64_insn_gen_move_reg(AARCH64_INSN_REG_9,
+ AARCH64_INSN_REG_LR,
+ AARCH64_INSN_VARIANT_64BIT);
+ return ftrace_modify_code(pc, old, new, true);
+}
+#endif
/*
* Turn off the call to ftrace_caller() in instrumented function
@@ -149,59 +214,35 @@
unsigned long addr)
{
unsigned long pc = rec->ip;
- bool validate = true;
u32 old = 0, new;
- long offset = (long)pc - (long)addr;
-
- if (offset < -SZ_128M || offset >= SZ_128M) {
-#ifdef CONFIG_ARM64_MODULE_PLTS
- u32 replaced;
-
- /*
- * 'mod' is only set at module load time, but if we end up
- * dealing with an out-of-range condition, we can assume it
- * is due to a module being loaded far away from the kernel.
- */
- if (!mod) {
- preempt_disable();
- mod = __module_text_address(pc);
- preempt_enable();
-
- if (WARN_ON(!mod))
- return -EINVAL;
- }
-
- /*
- * The instruction we are about to patch may be a branch and
- * link instruction that was redirected via a PLT entry. In
- * this case, the normal validation will fail, but we can at
- * least check that we are dealing with a branch and link
- * instruction that points into the right module.
- */
- if (aarch64_insn_read((void *)pc, &replaced))
- return -EFAULT;
-
- if (!aarch64_insn_is_bl(replaced) ||
- !within_module(pc + aarch64_get_branch_offset(replaced),
- mod))
- return -EINVAL;
-
- validate = false;
-#else /* CONFIG_ARM64_MODULE_PLTS */
- return -EINVAL;
-#endif /* CONFIG_ARM64_MODULE_PLTS */
- } else {
- old = aarch64_insn_gen_branch_imm(pc, addr,
- AARCH64_INSN_BRANCH_LINK);
- }
new = aarch64_insn_gen_nop();
- return ftrace_modify_code(pc, old, new, validate);
+ /*
+ * When using mcount, callsites in modules may have been initalized to
+ * call an arbitrary module PLT (which redirects to the _mcount stub)
+ * rather than the ftrace PLT we'll use at runtime (which redirects to
+ * the ftrace trampoline). We can ignore the old PLT when initializing
+ * the callsite.
+ *
+ * Note: 'mod' is only set at module load time.
+ */
+ if (!IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS) &&
+ IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) && mod) {
+ return aarch64_insn_patch_text_nosync((void *)pc, new);
+ }
+
+ if (!ftrace_find_callable_addr(rec, mod, &addr))
+ return -EINVAL;
+
+ old = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
+
+ return ftrace_modify_code(pc, old, new, true);
}
void arch_ftrace_update_code(int command)
{
+ command |= FTRACE_MAY_SLEEP;
ftrace_modify_all_code(command);
}
@@ -220,7 +261,7 @@
*
* Note that @frame_pointer is used only for sanity check later.
*/
-void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
+void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent,
unsigned long frame_pointer)
{
unsigned long return_hooker = (unsigned long)&return_to_handler;
--
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