linux-kernel - [RFC PATCH makedumpfile v3 1/3] elf_info.c: Introduce is_pmem_pt_load

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Date:   Fri,  2 Jun 2023 18:26:54 +0800
From:   Li Zhijian <lizhijian@...itsu.com>
To:     kexec@...ts.infradead.org, nvdimm@...ts.linux.dev
Cc:     linux-kernel@...r.kernel.org, dan.j.williams@...el.com,
        bhe@...hat.com, ruansy.fnst@...itsu.com, y-goto@...itsu.com,
        yangx.jy@...itsu.com, Li Zhijian <lizhijian@...itsu.com>,
        Vivek Goyal <vgoyal@...hat.com>, Dave Young <dyoung@...hat.com>
Subject: [RFC PATCH makedumpfile v3 1/3] elf_info.c: Introduce is_pmem_pt_load_range

It checks BIT(4) of Elf64_Phdr, currently only the former 3 bits are used
by ELF. In kexec-tool, we extend the BIT(4) to indicate pmem or not.

dump_Elf_load:                phys_start         phys_end       virt_start         virt_end  is_pmem
dump_Elf_load: LOAD[ 0]         6b800000         6e42c000 ffffffffbcc00000 ffffffffbf82c000    false
dump_Elf_load: LOAD[ 1]             1000            9fc00 ffff975980001000 ffff97598009fc00    false
dump_Elf_load: LOAD[ 2]           100000         7f000000 ffff975980100000 ffff9759ff000000    false
dump_Elf_load: LOAD[ 3]         bf000000         bffd7000 ffff975a3f000000 ffff975a3ffd7000    false
dump_Elf_load: LOAD[ 4]        100000000        140000000 ffff975a80000000 ffff975ac0000000    false
dump_Elf_load: LOAD[ 5]        140000000        23e200000 ffff975ac0000000 ffff975bbe200000     true

CC: Baoquan He <bhe@...hat.com>
CC: Vivek Goyal <vgoyal@...hat.com>
CC: Dave Young <dyoung@...hat.com>
CC: kexec@...ts.infradead.org
Signed-off-by: Li Zhijian <lizhijian@...itsu.com>
---
 elf_info.c | 31 +++++++++++++++++++++++++++----
 elf_info.h |  1 +
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/elf_info.c b/elf_info.c
index bc24083655d6..41b36b2804d2 100644
--- a/elf_info.c
+++ b/elf_info.c
@@ -43,6 +43,7 @@ struct pt_load_segment {
 	unsigned long long	phys_end;
 	unsigned long long	virt_start;
 	unsigned long long	virt_end;
+	int			is_pmem;
 };
 
 static int			nr_cpus;             /* number of cpu */
@@ -153,6 +154,8 @@ check_elf_format(int fd, char *filename, int *phnum, unsigned int *num_load)
 	return FALSE;
 }
 
+#define PF_DEV (1 << 4)
+
 static int
 dump_Elf_load(Elf64_Phdr *prog, int num_load)
 {
@@ -170,17 +173,37 @@ dump_Elf_load(Elf64_Phdr *prog, int num_load)
 	pls->virt_end    = pls->virt_start + prog->p_memsz;
 	pls->file_offset = prog->p_offset;
 	pls->file_size   = prog->p_filesz;
+	pls->is_pmem     = !!(prog->p_flags & PF_DEV);
 
 	if (num_load == 0)
-		DEBUG_MSG("%8s %16s %16s %16s %16s\n", "",
-			"phys_start", "phys_end", "virt_start", "virt_end");
+		DEBUG_MSG("%8s %16s %16s %16s %16s %8s\n", "",
+			"phys_start", "phys_end", "virt_start", "virt_end",
+			"is_pmem");
 
-	DEBUG_MSG("LOAD[%2d] %16llx %16llx %16llx %16llx\n", num_load,
-		pls->phys_start, pls->phys_end, pls->virt_start, pls->virt_end);
+	DEBUG_MSG("LOAD[%2d] %16llx %16llx %16llx %16llx %8s\n", num_load,
+		pls->phys_start, pls->phys_end, pls->virt_start, pls->virt_end,
+		pls->is_pmem ? "true": "false");
 
 	return TRUE;
 }
 
+int is_pmem_pt_load_range(unsigned long long start, unsigned long long end)
+{
+	int i;
+	struct pt_load_segment *pls;
+
+	for (i = 0; i < num_pt_loads; i++) {
+		pls = &pt_loads[i];
+		if (pls->is_pmem && pls->phys_start == NOT_PADDR)
+			return TRUE;
+		if (pls->is_pmem && pls->phys_start != NOT_PADDR &&
+		    pls->phys_start <= start && pls->phys_end >= end)
+			return TRUE;
+	}
+
+	return FALSE;
+}
+
 static off_t
 offset_next_note(void *note)
 {
diff --git a/elf_info.h b/elf_info.h
index d5416b32cdd7..a08d59a331f6 100644
--- a/elf_info.h
+++ b/elf_info.h
@@ -64,6 +64,7 @@ int get_pt_load_extents(int idx,
 	off_t *file_offset,
 	off_t *file_size);
 unsigned int get_num_pt_loads(void);
+int is_pmem_pt_load_range(unsigned long long start, unsigned long long end);
 
 void set_nr_cpus(int num);
 int get_nr_cpus(void);
-- 
2.29.2