[PATCH] powerpc: Unify mem= handling

We currently do mem= handling in three seperate places. And as benh pointed out
I wrote two of them. Now that we parse command line parameters earlier we can
clean this mess up.

Moving the parsing out of prom_init means the device tree might be allocated
above the memory limit. If that happens we'd have to move it. As it happens
we already have logic to do that for kdump, so just genericise it.

This also means we might have reserved regions above the memory limit, if we
do the bootmem allocator will blow up, so we have to modify
lmb_enforce_memory_limit() to truncate the reserves as well.

Tested on P5 LPAR, iSeries, F50, 44p. Tested moving device tree on P5 and
44p and F50.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 47 insertions, 42 deletions

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 4ca608c9cd72..a04f726d3bab 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -50,6 +50,7 @@
 #include <asm/machdep.h>
 #include <asm/pSeries_reconfig.h>
 #include <asm/pci-bridge.h>
+#include <asm/kexec.h>
 
 #ifdef DEBUG
 #define DBG(fmt...) printk(KERN_ERR fmt)
@@ -836,6 +837,42 @@ static unsigned long __init unflatten_dt_node(unsigned long mem,
         return mem;
 }
 
+static int __init early_parse_mem(char *p)
+{
+        if (!p)
+                return 1;
+
+        memory_limit = PAGE_ALIGN(memparse(p, &p));
+        DBG("memory limit = 0x%lx\n", memory_limit);
+
+        return 0;
+}
+early_param("mem", early_parse_mem);
+
+/*
+ * The device tree may be allocated below our memory limit, or inside the
+ * crash kernel region for kdump. If so, move it out now.
+ */
+static void move_device_tree(void)
+{
+        unsigned long start, size;
+        void *p;
+
+        DBG("-> move_device_tree\n");
+
+        start = __pa(initial_boot_params);
+        size = initial_boot_params->totalsize;
+
+        if ((memory_limit && (start + size) > memory_limit) ||
+                        overlaps_crashkernel(start, size)) {
+                p = __va(lmb_alloc_base(size, PAGE_SIZE, lmb.rmo_size));
+                memcpy(p, initial_boot_params, size);
+                initial_boot_params = (struct boot_param_header *)p;
+                DBG("Moved device tree to 0x%p\n", p);
+        }
+
+        DBG("<- move_device_tree\n");
+}
 
 /**
  * unflattens the device-tree passed by the firmware, creating the
@@ -1070,6 +1107,7 @@ static int __init early_init_dt_scan_chosen(unsigned long node,
                 iommu_force_on = 1;
 #endif
 
+        /* mem=x on the command line is the preferred mechanism */
         lprop = of_get_flat_dt_prop(node, "linux,memory-limit", NULL);
         if (lprop)
                 memory_limit = *lprop;
@@ -1123,17 +1161,6 @@ static int __init early_init_dt_scan_chosen(unsigned long node,
 
         DBG("Command line is: %s\n", cmd_line);
 
-        if (strstr(cmd_line, "mem=")) {
-                char *p, *q;
-
-                for (q = cmd_line; (p = strstr(q, "mem=")) != 0; ) {
-                        q = p + 4;
-                        if (p > cmd_line && p[-1] != ' ')
-                                continue;
-                        memory_limit = memparse(q, &q);
-                }
-        }
-
         /* break now */
         return 1;
 }
@@ -1297,11 +1324,6 @@ void __init early_init_devtree(void *params)
         strlcpy(saved_command_line, cmd_line, COMMAND_LINE_SIZE);
         parse_early_param();
 
-        lmb_enforce_memory_limit(memory_limit);
-        lmb_analyze();
-
-        DBG("Phys. mem: %lx\n", lmb_phys_mem_size());
-
         /* Reserve LMB regions used by kernel, initrd, dt, etc... */
         lmb_reserve(PHYSICAL_START, __pa(klimit) - PHYSICAL_START);
 #ifdef CONFIG_CRASH_DUMP
@@ -1309,6 +1331,15 @@ void __init early_init_devtree(void *params)
 #endif
         early_reserve_mem();
 
+        lmb_enforce_memory_limit(memory_limit);
+        lmb_analyze();
+
+        DBG("Phys. mem: %lx\n", lmb_phys_mem_size());
+
+        /* We may need to relocate the flat tree, do it now.
+         * FIXME .. and the initrd too? */
+        move_device_tree();
+
         DBG("Scanning CPUs ...\n");
 
         /* Retreive CPU related informations from the flat tree
@@ -2058,29 +2089,3 @@ int prom_update_property(struct device_node *np,
         return 0;
 }
 
-#ifdef CONFIG_KEXEC
-/* We may have allocated the flat device tree inside the crash kernel region
- * in prom_init. If so we need to move it out into regular memory. */
-void kdump_move_device_tree(void)
-{
-        unsigned long start, end;
-        struct boot_param_header *new;
-
-        start = __pa((unsigned long)initial_boot_params);
-        end = start + initial_boot_params->totalsize;
-
-        if (end < crashk_res.start || start > crashk_res.end)
-                return;
-
-        new = (struct boot_param_header*)
-                __va(lmb_alloc(initial_boot_params->totalsize, PAGE_SIZE));
-
-        memcpy(new, initial_boot_params, initial_boot_params->totalsize);
-
-        initial_boot_params = new;
-
-        DBG("Flat device tree blob moved to %p\n", initial_boot_params);
-
-        /* XXX should we unreserve the old DT? */
-}
-#endif /* CONFIG_KEXEC */