linux-kernel - [PATCH fixes] riscv/purgatory: 4B align purgatory

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Message-ID: <20250328085313.1193815-1-bjorn@kernel.org>
Date: Fri, 28 Mar 2025 09:53:11 +0100
From: Björn Töpel <bjorn@...nel.org>
To: Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Alexandre Ghiti <alex@...ti.fr>,
	linux-riscv@...ts.infradead.org
Cc: Björn Töpel <bjorn@...osinc.com>,
	Daniel Maslowski <cyrevolt@...glemail.com>,
	Li Zhengyu <lizhengyu3@...wei.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH fixes] riscv/purgatory: 4B align purgatory_start

From: Björn Töpel <bjorn@...osinc.com>

When a crashkernel is launched on RISC-V, the entry to purgatory is
done by trapping via the stvec CSR. From riscv_kexec_norelocate():

  |  ...
  |  /*
  |   * Switch to physical addressing
  |   * This will also trigger a jump to CSR_STVEC
  |   * which in this case is the address of the new
  |   * kernel.
  |   */
  |  csrw    CSR_STVEC, a2
  |  csrw    CSR_SATP, zero

stvec requires that the address is 4B aligned, which was not the case,
e.g.:

  | Loaded purgatory at 0xffffc000
  | kexec_file: kexec_file_load: type:1, start:0xffffd232 head:0x4 flags:0x6

The address 0xffffd232 not 4B aligned.

Correct by adding proper function alignment.

With this change, crashkernels loaded with kexec-file will be able to
properly enter the purgatory.

Fixes: 736e30af583fb ("RISC-V: Add purgatory")
Signed-off-by: Björn Töpel <bjorn@...osinc.com>
---
 arch/riscv/purgatory/entry.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/purgatory/entry.S b/arch/riscv/purgatory/entry.S
index 0e6ca6d5ae4b..c5db2f072c34 100644
--- a/arch/riscv/purgatory/entry.S
+++ b/arch/riscv/purgatory/entry.S
@@ -12,6 +12,7 @@
 
 .text
 
+.align	2
 SYM_CODE_START(purgatory_start)
 
 	lla	sp, .Lstack

base-commit: acb4f33713b9f6cadb6143f211714c343465411c
-- 
2.45.2