s390/boot: Add startup debugging support

Add boot_debug() calls to log various memory layout decisions and
randomization details during early startup, improving debugging
capabilities.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 89f1d12f1c100092d25bd13647d2d30f7fe84b23..807594cf246c1936bd446246f4f9ac60a470f9ec 100644 (file)
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0
+#define boot_fmt(fmt) "startup: " fmt
 #include <linux/string.h>
 #include <linux/elf.h>
 #include <asm/page-states.h>
@@ -223,12 +224,16 @@ static void setup_ident_map_size(unsigned long max_physmem_end)
        if (oldmem_data.start) {
                __kaslr_enabled = 0;
                ident_map_size = min(ident_map_size, oldmem_data.size);
+               boot_debug("kdump memory limit:  0x%016lx\n", oldmem_data.size);
        } else if (ipl_block_valid && is_ipl_block_dump()) {
                __kaslr_enabled = 0;
-               if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size)
+               if (!sclp_early_get_hsa_size(&hsa_size) && hsa_size) {
                        ident_map_size = min(ident_map_size, hsa_size);
+                       boot_debug("Stand-alone dump limit: 0x%016lx\n", hsa_size);
+               }
        }
 #endif
+       boot_debug("Identity map size:   0x%016lx\n", ident_map_size);
 }
 
 #define FIXMAP_SIZE    round_up(MEMCPY_REAL_SIZE + ABS_LOWCORE_MAP_SIZE, sizeof(struct lowcore))
@@ -266,6 +271,7 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
        BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE));
        BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE);
        vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE);
+       boot_debug("vmem size estimated: 0x%016lx\n", vsize);
        if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE ||
            (vsize > _REGION2_SIZE && kaslr_enabled())) {
                asce_limit = _REGION1_SIZE;
@@ -289,8 +295,10 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
         * otherwise asce_limit and rte_size would have been adjusted.
         */
        vmax = adjust_to_uv_max(asce_limit);
+       boot_debug("%d level paging       0x%016lx vmax\n", vmax == _REGION1_SIZE ? 4 : 3, vmax);
 #ifdef CONFIG_KASAN
        BUILD_BUG_ON(__NO_KASLR_END_KERNEL > KASAN_SHADOW_START);
+       boot_debug("KASAN shadow area:   0x%016lx-0x%016lx\n", KASAN_SHADOW_START, KASAN_SHADOW_END);
        /* force vmalloc and modules below kasan shadow */
        vmax = min(vmax, KASAN_SHADOW_START);
 #endif
@@ -304,19 +312,27 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
                        pos = 0;
                kernel_end = vmax - pos * THREAD_SIZE;
                kernel_start = round_down(kernel_end - kernel_size, THREAD_SIZE);
+               boot_debug("Randomization range: 0x%016lx-0x%016lx\n", vmax - kaslr_len, vmax);
+               boot_debug("kernel image:        0x%016lx-0x%016lx (kaslr)\n", kernel_start,
+                          kernel_size + kernel_size);
        } else if (vmax < __NO_KASLR_END_KERNEL || vsize > __NO_KASLR_END_KERNEL) {
                kernel_start = round_down(vmax - kernel_size, THREAD_SIZE);
-               boot_debug("The kernel base address is forced to %lx\n", kernel_start);
+               boot_debug("kernel image:        0x%016lx-0x%016lx (constrained)\n", kernel_start,
+                          kernel_start + kernel_size);
        } else {
                kernel_start = __NO_KASLR_START_KERNEL;
+               boot_debug("kernel image:        0x%016lx-0x%016lx (nokaslr)\n", kernel_start,
+                          kernel_start + kernel_size);
        }
        __kaslr_offset = kernel_start;
+       boot_debug("__kaslr_offset:      0x%016lx\n", __kaslr_offset);
 
        MODULES_END = round_down(kernel_start, _SEGMENT_SIZE);
        MODULES_VADDR = MODULES_END - MODULES_LEN;
        VMALLOC_END = MODULES_VADDR;
        if (IS_ENABLED(CONFIG_KMSAN))
                VMALLOC_END -= MODULES_LEN * 2;
+       boot_debug("modules area:        0x%016lx-0x%016lx\n", MODULES_VADDR, MODULES_END);
 
        /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */
        vsize = (VMALLOC_END - FIXMAP_SIZE) / 2;
@@ -328,10 +344,15 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
                VMALLOC_END -= vmalloc_size * 2;
        }
        VMALLOC_START = VMALLOC_END - vmalloc_size;
+       boot_debug("vmalloc area:        0x%016lx-0x%016lx\n", VMALLOC_START, VMALLOC_END);
 
        __memcpy_real_area = round_down(VMALLOC_START - MEMCPY_REAL_SIZE, PAGE_SIZE);
+       boot_debug("memcpy real area:    0x%016lx-0x%016lx\n", __memcpy_real_area,
+                  __memcpy_real_area + MEMCPY_REAL_SIZE);
        __abs_lowcore = round_down(__memcpy_real_area - ABS_LOWCORE_MAP_SIZE,
                                   sizeof(struct lowcore));
+       boot_debug("abs lowcore:         0x%016lx-0x%016lx\n", __abs_lowcore,
+                  __abs_lowcore + ABS_LOWCORE_MAP_SIZE);
 
        /* split remaining virtual space between 1:1 mapping & vmemmap array */
        pages = __abs_lowcore / (PAGE_SIZE + sizeof(struct page));
@@ -353,6 +374,8 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size)
        max_mappable = min(max_mappable, vmemmap_start);
        if (IS_ENABLED(CONFIG_RANDOMIZE_IDENTITY_BASE))
                __identity_base = round_down(vmemmap_start - max_mappable, rte_size);
+       boot_debug("identity map:        0x%016lx-0x%016lx\n", __identity_base,
+                  __identity_base + ident_map_size);
 
        return asce_limit;
 }
@@ -542,5 +565,6 @@ void startup_kernel(void)
         */
        psw.addr = __kaslr_offset + vmlinux.entry;
        psw.mask = PSW_KERNEL_BITS;
+       boot_debug("Starting kernel at:  0x%016lx\n", psw.addr);
        __load_psw(psw);
 }