Re: Patch "kexec: define functions to map and unmap segments" has been added to the 6.12-stable tree

[steven chen <chenste@linux.microsoft.com>]

On 3/8/2026 9:41 AM, Sasha Levin wrote:
> This is a note to let you know that I've just added the patch titled
>
>      kexec: define functions to map and unmap segments
>
> to the 6.12-stable tree which can be found at:
>      http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
>
> The filename of the patch is:
>       kexec-define-functions-to-map-and-unmap-segments.patch
> and it can be found in the queue-6.12 subdirectory.
>
> If you, or anyone else, feels it should not be added to the stable tree,
> please let <stable@vger.kernel.org> know about it.
>
>
>
> commit 51827bfcdc1c02aa4ea01b7aadcea8c2b8250666
> Author: Steven Chen <chenste@linux.microsoft.com>
> Date:   Mon Apr 21 15:25:09 2025 -0700
>
>      kexec: define functions to map and unmap segments
>      
>      [ Upstream commit 0091d9241ea24c5275be4a3e5a032862fd9de9ec ]
>      
>      Implement kimage_map_segment() to enable IMA to map the measurement log
>      list to the kimage structure during the kexec 'load' stage. This function
>      gathers the source pages within the specified address range, and maps them
>      to a contiguous virtual address range.
>      
>      This is a preparation for later usage.
>      
>      Implement kimage_unmap_segment() for unmapping segments using vunmap().
>      
>      Cc: Eric Biederman <ebiederm@xmission.com>
>      Cc: Baoquan He <bhe@redhat.com>
>      Cc: Vivek Goyal <vgoyal@redhat.com>
>      Cc: Dave Young <dyoung@redhat.com>
>      Co-developed-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
>      Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
>      Signed-off-by: Steven Chen <chenste@linux.microsoft.com>
>      Acked-by: Baoquan He <bhe@redhat.com>
>      Tested-by: Stefan Berger <stefanb@linux.ibm.com> # ppc64/kvm
>      Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
>      Stable-dep-of: 10d1c75ed438 ("ima: verify the previous kernel's IMA buffer lies in addressable RAM")
>      Signed-off-by: Sasha Levin <sashal@kernel.org>
>
> diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> index f0e9f8eda7a3c..7d6b12f8b8d05 100644
> --- a/include/linux/kexec.h
> +++ b/include/linux/kexec.h
> @@ -467,13 +467,19 @@ extern bool kexec_file_dbg_print;
>   #define kexec_dprintk(fmt, arg...) \
>           do { if (kexec_file_dbg_print) pr_info(fmt, ##arg); } while (0)
>   
> +extern void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size);
> +extern void kimage_unmap_segment(void *buffer);
>   #else /* !CONFIG_KEXEC_CORE */
>   struct pt_regs;
>   struct task_struct;
> +struct kimage;
>   static inline void __crash_kexec(struct pt_regs *regs) { }
>   static inline void crash_kexec(struct pt_regs *regs) { }
>   static inline int kexec_should_crash(struct task_struct *p) { return 0; }
>   static inline int kexec_crash_loaded(void) { return 0; }
> +static inline void *kimage_map_segment(struct kimage *image, unsigned long addr, unsigned long size)
> +{ return NULL; }
> +static inline void kimage_unmap_segment(void *buffer) { }
>   #define kexec_in_progress false
>   #endif /* CONFIG_KEXEC_CORE */
>   
> diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
> index c0caa14880c3b..6c15cd5b9cae5 100644
> --- a/kernel/kexec_core.c
> +++ b/kernel/kexec_core.c
> @@ -867,6 +867,60 @@ int kimage_load_segment(struct kimage *image,
>   	return result;
>   }
>   
> +void *kimage_map_segment(struct kimage *image,
> +			 unsigned long addr, unsigned long size)
> +{

please consider the following patch applicable or not:

[PATCH 1/2] kernel/kexec: Change the prototype of kimage_map_segment() - 
Pingfan Liu 
<https://lore.kernel.org/linux-integrity/20251105130922.13321-1-piliu@redhat.com/>

Steven

> +	unsigned long src_page_addr, dest_page_addr = 0;
> +	unsigned long eaddr = addr + size;
> +	kimage_entry_t *ptr, entry;
> +	struct page **src_pages;
> +	unsigned int npages;
> +	void *vaddr = NULL;
> +	int i;
> +
> +	/*
> +	 * Collect the source pages and map them in a contiguous VA range.
> +	 */
> +	npages = PFN_UP(eaddr) - PFN_DOWN(addr);
> +	src_pages = kmalloc_array(npages, sizeof(*src_pages), GFP_KERNEL);
> +	if (!src_pages) {
> +		pr_err("Could not allocate ima pages array.\n");
> +		return NULL;
> +	}
> +
> +	i = 0;
> +	for_each_kimage_entry(image, ptr, entry) {
> +		if (entry & IND_DESTINATION) {
> +			dest_page_addr = entry & PAGE_MASK;
> +		} else if (entry & IND_SOURCE) {
> +			if (dest_page_addr >= addr && dest_page_addr < eaddr) {
> +				src_page_addr = entry & PAGE_MASK;
> +				src_pages[i++] =
> +					virt_to_page(__va(src_page_addr));
> +				if (i == npages)
> +					break;
> +				dest_page_addr += PAGE_SIZE;
> +			}
> +		}
> +	}
> +
> +	/* Sanity check. */
> +	WARN_ON(i < npages);
> +
> +	vaddr = vmap(src_pages, npages, VM_MAP, PAGE_KERNEL);
> +	kfree(src_pages);
> +
> +	if (!vaddr)
> +		pr_err("Could not map ima buffer.\n");
> +
> +	return vaddr;
> +}
> +
> +void kimage_unmap_segment(void *segment_buffer)
> +{
> +	vunmap(segment_buffer);
> +}
> +
>   struct kexec_load_limit {
>   	/* Mutex protects the limit count. */
>   	struct mutex mutex;