arm64: kexec: skip relocation code for inplace kexec

In case of kdump or when segments are already in place the relocation
is not needed, therefore the setup of relocation function and call to
it can be skipped.

Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Suggested-by: James Morse <james.morse@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210930143113.1502553-6-pasha.tatashin@soleen.com
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index b6d5a02..7f1cb5a 100644 (file)
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -144,16 +144,16 @@ int machine_kexec_post_load(struct kimage *kimage)
 {
        void *reloc_code = page_to_virt(kimage->control_code_page);
 
-       /* If in place flush new kernel image, else flush lists and buffers */
-       if (kimage->head & IND_DONE)
+       /* If in place, relocation is not used, only flush next kernel */
+       if (kimage->head & IND_DONE) {
                kexec_segment_flush(kimage);
-       else
-               kexec_list_flush(kimage);
+               kexec_image_info(kimage);
+               return 0;
+       }
 
        memcpy(reloc_code, arm64_relocate_new_kernel,
               arm64_relocate_new_kernel_size);
        kimage->arch.kern_reloc = __pa(reloc_code);
-       kexec_image_info(kimage);
 
        /* Flush the reloc_code in preparation for its execution. */
        dcache_clean_inval_poc((unsigned long)reloc_code,
@@ -162,6 +162,8 @@ int machine_kexec_post_load(struct kimage *kimage)
        icache_inval_pou((uintptr_t)reloc_code,
                         (uintptr_t)reloc_code +
                         arm64_relocate_new_kernel_size);
+       kexec_list_flush(kimage);
+       kexec_image_info(kimage);
 
        return 0;
 }
@@ -188,19 +190,25 @@ void machine_kexec(struct kimage *kimage)
        local_daif_mask();
 
        /*
-        * cpu_soft_restart will shutdown the MMU, disable data caches, then
-        * transfer control to the kern_reloc which contains a copy of
-        * the arm64_relocate_new_kernel routine.  arm64_relocate_new_kernel
-        * uses physical addressing to relocate the new image to its final
-        * position and transfers control to the image entry point when the
-        * relocation is complete.
+        * Both restart and cpu_soft_restart will shutdown the MMU, disable data
+        * caches. However, restart will start new kernel or purgatory directly,
+        * cpu_soft_restart will transfer control to arm64_relocate_new_kernel
         * In kexec case, kimage->start points to purgatory assuming that
         * kernel entry and dtb address are embedded in purgatory by
         * userspace (kexec-tools).
         * In kexec_file case, the kernel starts directly without purgatory.
         */
-       cpu_soft_restart(kimage->arch.kern_reloc, kimage->head, kimage->start,
-                        kimage->arch.dtb_mem);
+       if (kimage->head & IND_DONE) {
+               typeof(__cpu_soft_restart) *restart;
+
+               cpu_install_idmap();
+               restart = (void *)__pa_symbol(function_nocfi(__cpu_soft_restart));
+               restart(is_hyp_nvhe(), kimage->start, kimage->arch.dtb_mem,
+                       0, 0);
+       } else {
+               cpu_soft_restart(kimage->arch.kern_reloc, kimage->head,
+                                kimage->start, kimage->arch.dtb_mem);
+       }
 
        BUG(); /* Should never get here. */
 }

diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index b78ea5d..8058fab 100644 (file)
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -32,8 +32,6 @@ SYM_CODE_START(arm64_relocate_new_kernel)
        mov     x16, x0                         /* x16 = kimage_head */
        mov     x14, xzr                        /* x14 = entry ptr */
        mov     x13, xzr                        /* x13 = copy dest */
-       /* Check if the new image needs relocation. */
-       tbnz    x16, IND_DONE_BIT, .Ldone
        raw_dcache_line_size x15, x1            /* x15 = dcache line size */
 .Lloop:
        and     x12, x16, PAGE_MASK             /* x12 = addr */
@@ -65,7 +63,6 @@ SYM_CODE_START(arm64_relocate_new_kernel)
 .Lnext:
        ldr     x16, [x14], #8                  /* entry = *ptr++ */
        tbz     x16, IND_DONE_BIT, .Lloop       /* while (!(entry & DONE)) */
-.Ldone:
        /* wait for writes from copy_page to finish */
        dsb     nsh
        ic      iallu