kernel/kexec_file.c: allow archs to set purgatory load address

For s390 new kernels are loaded to fixed addresses in memory before they
are booted.  With the current code this is a problem as it assumes the
kernel will be loaded to an 'arbitrary' address.  In particular,
kexec_locate_mem_hole searches for a large enough memory region and sets
the load address (kexec_bufer->mem) to it.

Luckily there is a simple workaround for this problem.  By returning 1
in arch_kexec_walk_mem, kexec_locate_mem_hole is turned off.  This
allows the architecture to set kbuf->mem by hand.  While the trick works
fine for the kernel it does not for the purgatory as here the
architectures don't have access to its kexec_buffer.

Give architectures access to the purgatories kexec_buffer by changing
kexec_load_purgatory to take a pointer to it.  With this change
architectures have access to the buffer and can edit it as they need.

A nice side effect of this change is that we can get rid of the
purgatory_info->purgatory_load_address field.  As now the information
stored there can directly be accessed from kbuf->mem.

Link: http://lkml.kernel.org/r/20180321112751.22196-11-prudo@linux.vnet.ibm.com
Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/powerpc/kernel/kexec_elf_64.c b/arch/powerpc/kernel/kexec_elf_64.c
index 6c78c11c7faf46b5de710149c08e70b9cef87d32..ba4f18a43ee8b8f37c533c2d5cf3a4155ca59a02 100644 (file)
--- a/arch/powerpc/kernel/kexec_elf_64.c
+++ b/arch/powerpc/kernel/kexec_elf_64.c
@@ -572,7 +572,7 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 {
        int ret;
        unsigned int fdt_size;
-       unsigned long kernel_load_addr, purgatory_load_addr;
+       unsigned long kernel_load_addr;
        unsigned long initrd_load_addr = 0, fdt_load_addr;
        void *fdt;
        const void *slave_code;
@@ -580,6 +580,8 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
        struct elf_info elf_info;
        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 };
 
        ret = build_elf_exec_info(kernel_buf, kernel_len, &ehdr, &elf_info);
        if (ret)
@@ -591,14 +593,13 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 
        pr_debug("Loaded the kernel at 0x%lx\n", kernel_load_addr);
 
-       ret = kexec_load_purgatory(image, 0, ppc64_rma_size, true,
-                                  &purgatory_load_addr);
+       ret = kexec_load_purgatory(image, &pbuf);
        if (ret) {
                pr_err("Loading purgatory failed.\n");
                goto out;
        }
 
-       pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
+       pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
 
        if (initrd != NULL) {
                kbuf.buffer = initrd;

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 705654776c0c9fb7ebfcba29ded61c7e8de0114d..3182908b7e6c70c621f8e5f8446cb0cfbc850de9 100644 (file)
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -334,7 +334,6 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
        unsigned long setup_header_size, params_cmdline_sz;
        struct boot_params *params;
        unsigned long bootparam_load_addr, kernel_load_addr, initrd_load_addr;
-       unsigned long purgatory_load_addr;
        struct bzimage64_data *ldata;
        struct kexec_entry64_regs regs64;
        void *stack;
@@ -342,6 +341,8 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
        unsigned int efi_map_offset, efi_map_sz, efi_setup_data_offset;
        struct kexec_buf kbuf = { .image = image, .buf_max = ULONG_MAX,
                                  .top_down = true };
+       struct kexec_buf pbuf = { .image = image, .buf_min = MIN_PURGATORY_ADDR,
+                                 .buf_max = ULONG_MAX, .top_down = true };
 
        header = (struct setup_header *)(kernel + setup_hdr_offset);
        setup_sects = header->setup_sects;
@@ -379,14 +380,13 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
         * Load purgatory. For 64bit entry point, purgatory  code can be
         * anywhere.
         */
-       ret = kexec_load_purgatory(image, MIN_PURGATORY_ADDR, ULONG_MAX, 1,
-                                  &purgatory_load_addr);
+       ret = kexec_load_purgatory(image, &pbuf);
        if (ret) {
                pr_err("Loading purgatory failed\n");
                return ERR_PTR(ret);
        }
 
-       pr_debug("Loaded purgatory at 0x%lx\n", purgatory_load_addr);
+       pr_debug("Loaded purgatory at 0x%lx\n", pbuf.mem);
 
 
        /*

diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 0e389b9b77223204fab515df845810ca2ebcd14f..9e4e638fb5051b1337718535db5ae20b7a63c07c 100644 (file)
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -114,9 +114,6 @@ struct purgatory_info {
         * relocation. This memory can be freed post image load.
         */
        void *purgatory_buf;
-
-       /* Address where purgatory is finally loaded and is executed from */
-       unsigned long purgatory_load_addr;
 };
 
 struct kimage;
@@ -171,6 +168,12 @@ struct kexec_buf {
        bool top_down;
 };
 
+int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf);
+int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
+                                  void *buf, unsigned int size,
+                                  bool get_value);
+void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name);
+
 int __weak arch_kexec_apply_relocations_add(struct purgatory_info *pi,
                                            Elf_Shdr *section,
                                            const Elf_Shdr *relsec,
@@ -266,14 +269,6 @@ extern void machine_kexec_cleanup(struct kimage *image);
 extern int kernel_kexec(void);
 extern struct page *kimage_alloc_control_pages(struct kimage *image,
                                                unsigned int order);
-extern int kexec_load_purgatory(struct kimage *image, unsigned long min,
-                               unsigned long max, int top_down,
-                               unsigned long *load_addr);
-extern int kexec_purgatory_get_set_symbol(struct kimage *image,
-                                         const char *name, void *buf,
-                                         unsigned int size, bool get_value);
-extern void *kexec_purgatory_get_symbol_addr(struct kimage *image,
-                                            const char *name);
 extern void __crash_kexec(struct pt_regs *);
 extern void crash_kexec(struct pt_regs *);
 int kexec_should_crash(struct task_struct *);

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 269116fd932ca1a55a91f7522b27c8c2ae50a335..75d8e7cf040e69bfcde16fb555c09054cfe9ebad 100644 (file)
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -730,8 +730,8 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
        int i, ret;
 
        sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
-       bss_align = 1;
-       bss_sz = 0;
+       kbuf->buf_align = bss_align = 1;
+       kbuf->bufsz = bss_sz = 0;
 
        for (i = 0; i < pi->ehdr->e_shnum; i++) {
                if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@@ -763,7 +763,6 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
        ret = kexec_add_buffer(kbuf);
        if (ret)
                goto out;
-       pi->purgatory_load_addr = kbuf->mem;
 
        return 0;
 out:
@@ -901,27 +900,32 @@ static int kexec_apply_relocations(struct kimage *image)
        return 0;
 }
 
-/* Load relocatable purgatory object and relocate it appropriately */
-int kexec_load_purgatory(struct kimage *image, unsigned long min,
-                        unsigned long max, int top_down,
-                        unsigned long *load_addr)
+/*
+ * kexec_load_purgatory - Load and relocate the purgatory object.
+ * @image:     Image to add the purgatory to.
+ * @kbuf:      Memory parameters to use.
+ *
+ * Allocates the memory needed for image->purgatory_info.sechdrs and
+ * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
+ * to free the memory after use.
+ *
+ * Return: 0 on success, negative errno on error.
+ */
+int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
 {
        struct purgatory_info *pi = &image->purgatory_info;
        int ret;
-       struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
-                                 .buf_min = min, .buf_max = max,
-                                 .top_down = top_down };
 
        if (kexec_purgatory_size <= 0)
                return -EINVAL;
 
        pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
 
-       ret = kexec_purgatory_setup_kbuf(pi, &kbuf);
+       ret = kexec_purgatory_setup_kbuf(pi, kbuf);
        if (ret)
                return ret;
 
-       ret = kexec_purgatory_setup_sechdrs(pi, &kbuf);
+       ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
        if (ret)
                goto out_free_kbuf;
 
@@ -929,7 +933,6 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
        if (ret)
                goto out;
 
-       *load_addr = pi->purgatory_load_addr;
        return 0;
 out:
        vfree(pi->sechdrs);