powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load() [Linux 5.2]

powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load() [Linux 5.2]

This Linux kernel change "powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load()" is included in the Linux 5.2 release. This change is authored by Thiago Jung Bauermann <bauerman [at] linux.ibm.com> on Wed May 22 19:01:58 2019 -0300. The commit for this change in Linux stable tree is 8b909e3 (patch).

powerpc/kexec: Fix loading of kernel + initramfs with kexec_file_load()

Commit b6664ba42f14 ("s390, kexec_file: drop arch_kexec_mem_walk()")
changed kexec_add_buffer() to skip searching for a memory location if
kexec_buf.mem is already set, and use the address that is there.

In powerpc code we reuse a kexec_buf variable for loading both the
kernel and the initramfs by resetting some of the fields between those
uses, but not mem. This causes kexec_add_buffer() to try to load the
kernel at the same address where initramfs will be loaded, which is
naturally rejected:

  # kexec -s -l --initrd initramfs vmlinuz
  kexec_file_load failed: Invalid argument

Setting the mem field before every call to kexec_add_buffer() fixes
this regression.

Fixes: b6664ba42f14 ("s390, kexec_file: drop arch_kexec_mem_walk()")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 arch/powerpc/kernel/kexec_elf_64.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
index ba4f18a..52a29fc 100644
--- a/arch/powerpc/kernel/kexec_elf_64.c
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -547,6 +547,7 @@ static int elf_exec_load(struct kimage *image, struct elfhdr *ehdr,
        kbuf.memsz = phdr->p_memsz;
        kbuf.buf_align = phdr->p_align;
        kbuf.buf_min = phdr->p_paddr + base;
+       kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
            goto out;
@@ -581,7 +582,8 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
    struct kexec_buf kbuf = { .image = image, .buf_min = 0,
                  .buf_max = ppc64_rma_size };
    struct kexec_buf pbuf = { .image = image, .buf_min = 0,
-                 .buf_max = ppc64_rma_size, .top_down = true };
+                 .buf_max = ppc64_rma_size, .top_down = true,
+                 .mem = KEXEC_BUF_MEM_UNKNOWN };

    ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
    if (ret)
@@ -606,6 +608,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
        kbuf.bufsz = kbuf.memsz = initrd_len;
        kbuf.buf_align = PAGE_SIZE;
        kbuf.top_down = false;
+       kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
        ret = kexec_add_buffer(&kbuf);
        if (ret)
            goto out;
@@ -638,6 +641,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
    kbuf.bufsz = kbuf.memsz = fdt_size;
    kbuf.buf_align = PAGE_SIZE;
    kbuf.top_down = true;
+   kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;
    ret = kexec_add_buffer(&kbuf);
    if (ret)
        goto out;

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