[lwp][rv64] fix the load page fault occurring in the signal handler function

[eatvector]

拉取/合并请求描述：(PR description)

修复线程在信号处理函数中，访问TLS数据时出现load page fault异常，关联#10501
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为什么提交这份PR (why to submit this PR)

在rt-smart的riscv64架构中，当通过arch_thread_signal_enter从内核态切换到用户态信号处理程序时，未正确恢复线程指针(tp)寄存器。这会导致用户线程通过tp指针访问线程局部存储(TLS)时触发load page fault异常。

你的解决方案是什么 (what is your solution)

请提供验证的bsp和config (provide the config and bsp)

• BSP:

• .config:

• action:

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/workflows/bsp_buildings.yml 详细请参考链接BSP自查

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Path: components
Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/lwp/arch/risc-v/rv64/lwp_gcc.S

🏷️ Tag: lwp

Path: components/lwp
Reviewers: @xu18838022837

Changed Files (Click to expand)

• components/lwp/arch/risc-v/rv64/lwp_gcc.S

🏷️ Tag: rvlibcpu

Path: libcpu/risc-v
Reviewers: @Yaochenger

Changed Files (Click to expand)

• libcpu/risc-v/common64/stackframe.h

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📊 Current Review Status (Last Updated: 2025-07-12 13:21 UTC)

• ⌛ @Maihuanyi Pending Review
• ⌛ @Yaochenger Pending Review
• ⌛ @xu18838022837 Pending Review

---

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   Comment LGTM/lgtm after confirming approval

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   PR must be confirmed by at least one maintainer before merging

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[eatvector]

@BernardXiong 请问大佬有空帮忙审核一下这个吗，改动很小👀