[PATCH v2 12/12] s390/kdump: virtio-mem kdump support (CONFIG_PROC_VMCORE_DEVICE_RAM)

David Hildenbrand
2024-12-04T12:55:39Z

Let's add support for including virtio-mem device RAM in the crash dump,
setting NEED_PROC_VMCORE_DEVICE_RAM, and implementing
elfcorehdr_fill_device_ram_ptload_elf64().

To avoid code duplication, factor out the code to fill a PT_LOAD entry.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
arch/s390/Kconfig | 1 +
arch/s390/kernel/crash_dump.c | 39 ++++++++++++++++++++++++++++-------
2 files changed, 32 insertions(+), 8 deletions(-)

diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 0077969170e8..c230bad7f5cc 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -240,6 +240,7 @@ config S390
select MODULES_USE_ELF_RELA
select NEED_DMA_MAP_STATE if PCI
select NEED_PER_CPU_EMBED_FIRST_CHUNK
+ select NEED_PROC_VMCORE_DEVICE_RAM if PROC_VMCORE
select NEED_SG_DMA_LENGTH if PCI
select OLD_SIGACTION
select OLD_SIGSUSPEND3
diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c
index cd0c93a8fb8b..f699df2a2b11 100644
--- a/arch/s390/kernel/crash_dump.c
+++ b/arch/s390/kernel/crash_dump.c
@@ -508,6 +508,19 @@ static int get_mem_chunk_cnt(void)
return cnt;
}

+static void fill_ptload(Elf64_Phdr *phdr, unsigned long paddr,
+ unsigned long vaddr, unsigned long size)
+{
+ phdr->p_type = PT_LOAD;
+ phdr->p_vaddr = vaddr;
+ phdr->p_offset = paddr;
+ phdr->p_paddr = paddr;
+ phdr->p_filesz = size;
+ phdr->p_memsz = size;
+ phdr->p_flags = PF_R | PF_W | PF_X;
+ phdr->p_align = PAGE_SIZE;
+}
+
/*
* Initialize ELF loads (new kernel)
*/
@@ -520,14 +533,8 @@ static void loads_init(Elf64_Phdr *phdr, bool os_info_has_vm)
if (os_info_has_vm)
old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE);
for_each_physmem_range(idx, &oldmem_type, &start, &end) {
- phdr->p_type = PT_LOAD;
- phdr->p_vaddr = old_identity_base + start;
- phdr->p_offset = start;
- phdr->p_paddr = start;
- phdr->p_filesz = end - start;
- phdr->p_memsz = end - start;
- phdr->p_flags = PF_R | PF_W | PF_X;
- phdr->p_align = PAGE_SIZE;
+ fill_ptload(phdr, start, old_identity_base + start,
+ end - start);
phdr++;
}
}
@@ -537,6 +544,22 @@ static bool os_info_has_vm(void)
return os_info_old_value(OS_INFO_KASLR_OFFSET);
}

+#ifdef CONFIG_PROC_VMCORE_DEVICE_RAM
+/*
+ * Fill PT_LOAD for a physical memory range owned by a device and detected by
+ * its device driver.
+ */
+void elfcorehdr_fill_device_ram_ptload_elf64(Elf64_Phdr *phdr,
+ unsigned long long paddr, unsigned long long size)
+{
+ unsigned long old_identity_base = 0;
+
+ if (os_info_has_vm())
+ old_identity_base = os_info_old_value(OS_INFO_IDENTITY_BASE);
+ fill_ptload(phdr, paddr, old_identity_base + paddr, size);
+}
+#endif
+
/*
* Prepare PT_LOAD type program header for kernel image region
*/
--
2.47.1