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From: fangyu.yu@linux.alibaba.com
To: pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu,
	alex@ghiti.fr, songshuaishuai@tinylab.org, bjorn@rivosinc.com,
	ardb@kernel.org, arnd@arndb.de, bhelgaas@google.com,
	richard.lyu@suse.com, tzimmermann@suse.de, nathan@kernel.org
Cc: guoren@kernel.org, kvm-riscv@lists.infradead.org,
	linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	Fangyu Yu <fangyu.yu@linux.alibaba.com>
Subject: [PATCH 1/4] riscv: Add kexec trampoline text section to vmlinux.lds.S
Date: Tue, 24 Mar 2026 19:45:24 +0800	[thread overview]
Message-ID: <20260324114527.91494-2-fangyu.yu@linux.alibaba.com> (raw)
In-Reply-To: <20260324114527.91494-1-fangyu.yu@linux.alibaba.com>

From: Fangyu Yu <fangyu.yu@linux.alibaba.com>

When CONFIG_KEXEC_CORE is enabled, add a dedicated .kexec.tramp.text
area to the RISC-V kernel linker script.

This introduces a KEXEC_TRAMP_TEXT linker snippet in image-vars.h and
uses it from vmlinux.lds.S to:
  - align to PAGE_SIZE
  - define __kexec_tramp_text_start/__kexec_tramp_text_end
  - KEEP all .kexec.tramp.text* input sections
  - ASSERT the trampoline text fits within one page

When kexec is disabled, KEXEC_TRAMP_TEXT expands to nothing.

Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
---
 arch/riscv/kernel/image-vars.h  | 13 +++++++++++++
 arch/riscv/kernel/vmlinux.lds.S |  1 +
 2 files changed, 14 insertions(+)

diff --git a/arch/riscv/kernel/image-vars.h b/arch/riscv/kernel/image-vars.h
index 3bd9d06a8b8f..5419609ff89c 100644
--- a/arch/riscv/kernel/image-vars.h
+++ b/arch/riscv/kernel/image-vars.h
@@ -34,4 +34,17 @@ __efistub_sysfb_primary_display	= sysfb_primary_display;
 
 #endif
 
+#ifdef CONFIG_KEXEC_CORE
+#define KEXEC_TRAMP_TEXT						\
+		. = ALIGN(PAGE_SIZE);					\
+		__kexec_tramp_text_start = .;				\
+		KEEP(*(.kexec.tramp.text))				\
+		KEEP(*(.kexec.tramp.text.*))				\
+		__kexec_tramp_text_end = .;				\
+		ASSERT((__kexec_tramp_text_end - __kexec_tramp_text_start) <= PAGE_SIZE,  \
+			".kexec.tramp.text exceeds 4K");
+#else
+#define KEXEC_TRAMP_TEXT /* nothing */
+#endif
+
 #endif /* __RISCV_KERNEL_IMAGE_VARS_H */
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 997f9eb3b22b..c55316912c1d 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -45,6 +45,7 @@ SECTIONS
 		ENTRY_TEXT
 		IRQENTRY_TEXT
 		SOFTIRQENTRY_TEXT
+		KEXEC_TRAMP_TEXT
 		_etext = .;
 	}
 
-- 
2.50.1


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  reply	other threads:[~2026-03-24 11:46 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-24 11:45 [PATCH 0/4] Add crashdump support in guest kernel fangyu.yu
2026-03-24 11:45 ` fangyu.yu [this message]
2026-03-24 11:45 ` [PATCH 2/4] riscv: kexec: Place norelocate trampoline into .kexec.tramp.text fangyu.yu
2026-03-24 11:45 ` [PATCH 3/4] riscv: kexec: Build trampoline page tables for crash kernel entry fangyu.yu
2026-03-24 11:45 ` [PATCH 4/4] riscv: kexec: Switch to trampoline page table before norelocate fangyu.yu

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