[source] kernel: fix crashlog issues on highmem systems

[LEDE Commits]

nbd pushed a commit to source.git, branch master:
https://git.lede-project.org/?p=source.git;a=commitdiff;h=9d56ec6244e516fd80f8500aaa081c39ffeccf86

commit 9d56ec6244e516fd80f8500aaa081c39ffeccf86
Author: Felix Fietkau <nbd at nbd.name>
AuthorDate: Thu Aug 11 17:02:32 2016 +0200

    kernel: fix crashlog issues on highmem systems
    
    Signed-off-by: Felix Fietkau <nbd at nbd.name>
---
 .../linux/generic/patches-4.4/930-crashlog.patch   | 51 ++++++++++++++--------
 1 file changed, 32 insertions(+), 19 deletions(-)

diff --git a/target/linux/generic/patches-4.4/930-crashlog.patch b/target/linux/generic/patches-4.4/930-crashlog.patch
index 311a4f1..bb97c90 100644
--- a/target/linux/generic/patches-4.4/930-crashlog.patch
+++ b/target/linux/generic/patches-4.4/930-crashlog.patch
@@ -43,7 +43,7 @@
  
 --- /dev/null
 +++ b/kernel/crashlog.c
-@@ -0,0 +1,196 @@
+@@ -0,0 +1,209 @@
 +/*
 + * Crash information logger
 + * Copyright (C) 2010 Felix Fietkau <nbd at nbd.name>
@@ -103,40 +103,53 @@
 +
 +extern struct list_head *crashlog_modules;
 +
++static bool crashlog_set_addr(phys_addr_t addr, phys_addr_t size)
++{
++	/* Limit to lower 64 MB to avoid highmem */
++	phys_addr_t limit = 64 * 1024 * 1024;
++
++	if (crashlog_addr)
++		return false;
++
++	if (addr > limit)
++		return false;
++
++	if (addr + size > limit)
++		size = limit - addr;
++
++	crashlog_addr = addr + size - CRASHLOG_OFFSET;
++	return true;
++}
++
 +#ifndef CONFIG_NO_BOOTMEM
 +void __init crashlog_init_bootmem(bootmem_data_t *bdata)
 +{
-+	unsigned long addr;
++	phys_addr_t start, end;
 +
-+	if (crashlog_addr)
++	start = PFN_PHYS(bdata->node_low_pfn);
++	end = PFN_PHYS(bdata->node_min_pfn);
++	if (!crashlog_set_addr(start, end - start))
 +		return;
 +
-+	addr = PFN_PHYS(bdata->node_low_pfn) - CRASHLOG_OFFSET;
-+	if (reserve_bootmem(addr, CRASHLOG_SIZE, BOOTMEM_EXCLUSIVE) < 0) {
-+		printk("Crashlog failed to allocate RAM at address 0x%lx\n", addr);
-+		bdata->node_low_pfn -= CRASHLOG_PAGES;
-+		addr = PFN_PHYS(bdata->node_low_pfn);
++	if (reserve_bootmem(crashlog_addr, CRASHLOG_SIZE, BOOTMEM_EXCLUSIVE) < 0) {
++		printk("Crashlog failed to allocate RAM at address 0x%lx\n",
++		       crashlog_addr);
++		crashlog_addr = 0;
 +	}
-+	crashlog_addr = addr;
 +}
 +#endif
 +
 +#ifdef CONFIG_HAVE_MEMBLOCK
 +void __init_memblock crashlog_init_memblock(phys_addr_t addr, phys_addr_t size)
 +{
-+	if (crashlog_addr)
++	if (!crashlog_set_addr(addr, size))
 +		return;
 +
-+	if (size <= CRASHLOG_OFFSET + CRASHLOG_SIZE)
-+		return;
-+
-+	addr += size - CRASHLOG_OFFSET;
-+	if (memblock_reserve(addr, CRASHLOG_SIZE)) {
-+		printk("Crashlog failed to allocate RAM at address 0x%lx\n", (unsigned long) addr);
-+		return;
++	if (memblock_reserve(crashlog_addr, CRASHLOG_SIZE)) {
++		printk("Crashlog failed to allocate RAM at address 0x%lx\n",
++		       crashlog_addr);
++		crashlog_addr = 0;
 +	}
-+
-+	crashlog_addr = addr;
 +}
 +#endif
 +