[PATCH 6.6 108/139] powerpc/64s: Fix unnecessary copy to 0 when kernel is booted at address 0

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jinglin Wen <jinglin.wen@xxxxxxxxxxxx>

commit 13fc6c175924eaa953cf597ce28ffa4edc4554a6 upstream.

According to the code logic, when the kernel is loaded at address 0, no
copying operation should be performed, but it is currently being done.

This patch fixes the issue where the kernel code was incorrectly
duplicated to address 0 when booting from address 0.

Fixes: b270bebd34e3 ("powerpc/64s: Run at the kernel virtual address earlier in boot")
Cc: stable@xxxxxxxxxxxxxxx # v6.4+
Signed-off-by: Jinglin Wen <jinglin.wen@xxxxxxxxxxxx>
Suggested-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://msgid.link/20240620024150.14857-1-jinglin.wen@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/powerpc/kernel/head_64.S | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 4690c219bfa4..63432a33ec49 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -647,8 +647,9 @@ __after_prom_start:
  * Note: This process overwrites the OF exception vectors.
  */
 	LOAD_REG_IMMEDIATE(r3, PAGE_OFFSET)
-	mr.	r4,r26			/* In some cases the loader may  */
-	beq	9f			/* have already put us at zero */
+	mr	r4,r26			/* Load the virtual source address into r4 */
+	cmpld	r3,r4			/* Check if source == dest */
+	beq	9f			/* If so skip the copy  */
 	li	r6,0x100		/* Start offset, the first 0x100 */
 					/* bytes were copied earlier.	 */
 
-- 
2.45.2







[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux