[PATCH v4 7/8] vmcore: treat memory chunks referenced by PT_LOADprogram header entries in page-size boundary in vmcore_list

[HATAYAMA Daisuke]

Treat memory chunks referenced by PT_LOAD program header entries in
page-size boundary in vmcore_list. Formally, for each range [start,
end], we set up the corresponding vmcore object in vmcore_list to
[rounddown(start, PAGE_SIZE), roundup(end, PAGE_SIZE)].

This change affects layout of /proc/vmcore. The gaps generated by the
rearrangement are newly made visible to applications as
holes. Concretely, they are two ranges [rounddown(start, PAGE_SIZE),
start] and [end, roundup(end, PAGE_SIZE)].

Signed-off-by: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
---

 fs/proc/vmcore.c |   26 ++++++++++++++++++++------
 1 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index 029bdc0..cd0f9d9 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -477,16 +477,23 @@ static int __init process_ptload_program_headers_elf64(char *elfptr,
 	vmcore_off = elfsz + roundup(phdr_ptr->p_memsz, PAGE_SIZE);
 
 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
+		u64 paddr, start, end, size;
+
 		if (phdr_ptr->p_type != PT_LOAD)
 			continue;
 
+		paddr = phdr_ptr->p_offset;
+		start = rounddown(paddr, PAGE_SIZE);
+		end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
+		size = end - start;
+
 		/* Add this contiguous chunk of memory to vmcore list.*/
-		if (vmcore_add(vc_list, phdr_ptr->p_offset, phdr_ptr->p_memsz))
+		if (vmcore_add(vc_list, start, size))
 			return -ENOMEM;
 
 		/* Update the program header offset. */
-		phdr_ptr->p_offset = vmcore_off;
-		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
+		phdr_ptr->p_offset = vmcore_off + (paddr - start);
+		vmcore_off = vmcore_off + size;
 	}
 	return 0;
 }
@@ -507,16 +514,23 @@ static int __init process_ptload_program_headers_elf32(char *elfptr,
 	vmcore_off = elfsz + roundup(phdr_ptr->p_memsz, PAGE_SIZE);
 
 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
+		u64 paddr, start, end, size;
+
 		if (phdr_ptr->p_type != PT_LOAD)
 			continue;
 
+		paddr = phdr_ptr->p_offset;
+		start = rounddown(paddr, PAGE_SIZE);
+		end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
+		size = end - start;
+
 		/* Add this contiguous chunk of memory to vmcore list.*/
-		if (vmcore_add(vc_list, phdr_ptr->p_offset, phdr_ptr->p_memsz))
+		if (vmcore_add(vc_list, start, size))
 			return -ENOMEM;
 
 		/* Update the program header offset */
-		phdr_ptr->p_offset = vmcore_off;
-		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
+		phdr_ptr->p_offset = vmcore_off + (paddr - start);
+		vmcore_off = vmcore_off + size;
 	}
 	return 0;
 }

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