x86/efi: earlyprintk=efi,keep fix

earlyprintk=efi,keep will cause kernel hangs while freeing initmem like
below:

  VFS: Mounted root (ext4 filesystem) readonly on device 254:2.
  devtmpfs: mounted
  Freeing unused kernel memory: 880K (ffffffff817d4000 - ffffffff818b0000)

It is caused by efi earlyprintk use __init function which will be freed
later.  Such as early_efi_write is marked as __init, also it will use
early_ioremap which is init function as well.

To fix this issue, I added early initcall early_efi_map_fb which maps
the whole efi fb for later use. OTOH, adding a wrapper function
early_efi_map which calls early_ioremap before ioremap is available.

With this patch applied efi boot ok with earlyprintk=efi,keep console=efi

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 64 insertions, 19 deletions

diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c
index 81b506d5befd..524142117296 100644
--- a/arch/x86/platform/efi/early_printk.c
+++ b/arch/x86/platform/efi/early_printk.c
@@ -14,48 +14,92 @@
 
 static const struct font_desc *font;
 static u32 efi_x, efi_y;
+static void *efi_fb;
+static bool early_efi_keep;
 
-static __init void early_efi_clear_scanline(unsigned int y)
+/*
+ * efi earlyprintk need use early_ioremap to map the framebuffer.
+ * But early_ioremap is not usable for earlyprintk=efi,keep, ioremap should
+ * be used instead. ioremap will be available after paging_init() which is
+ * earlier than initcall callbacks. Thus adding this early initcall function
+ * early_efi_map_fb to map the whole efi framebuffer.
+ */
+static __init int early_efi_map_fb(void)
 {
-        unsigned long base, *dst;
-        u16 len;
+        unsigned long base, size;
+
+        if (!early_efi_keep)
+                return 0;
 
         base = boot_params.screen_info.lfb_base;
-        len = boot_params.screen_info.lfb_linelength;
+        size = boot_params.screen_info.lfb_size;
+        efi_fb = ioremap(base, size);
+
+        return efi_fb ? 0 : -ENOMEM;
+}
+early_initcall(early_efi_map_fb);
+
+/*
+ * early_efi_map maps efi framebuffer region [start, start + len -1]
+ * In case earlyprintk=efi,keep we have the whole framebuffer mapped already
+ * so just return the offset efi_fb + start.
+ */
+static __init_refok void *early_efi_map(unsigned long start, unsigned long len)
+{
+        unsigned long base;
+
+        base = boot_params.screen_info.lfb_base;
+
+        if (efi_fb)
+                return (efi_fb + start);
+        else
+                return early_ioremap(base + start, len);
+}
 
-        dst = early_ioremap(base + y*len, len);
+static __init_refok void early_efi_unmap(void *addr, unsigned long len)
+{
+        if (!efi_fb)
+                early_iounmap(addr, len);
+}
+
+static void early_efi_clear_scanline(unsigned int y)
+{
+        unsigned long *dst;
+        u16 len;
+
+        len = boot_params.screen_info.lfb_linelength;
+        dst = early_efi_map(y*len, len);
         if (!dst)
                 return;
 
         memset(dst, 0, len);
-        early_iounmap(dst, len);
+        early_efi_unmap(dst, len);
 }
 
-static __init void early_efi_scroll_up(void)
+static void early_efi_scroll_up(void)
 {
-        unsigned long base, *dst, *src;
+        unsigned long *dst, *src;
         u16 len;
         u32 i, height;
 
-        base = boot_params.screen_info.lfb_base;
         len = boot_params.screen_info.lfb_linelength;
         height = boot_params.screen_info.lfb_height;
 
         for (i = 0; i < height - font->height; i++) {
-                dst = early_ioremap(base + i*len, len);
+                dst = early_efi_map(i*len, len);
                 if (!dst)
                         return;
 
-                src = early_ioremap(base + (i + font->height) * len, len);
+                src = early_efi_map((i + font->height) * len, len);
                 if (!src) {
-                        early_iounmap(dst, len);
+                        early_efi_unmap(dst, len);
                         return;
                 }
 
                 memmove(dst, src, len);
 
-                early_iounmap(src, len);
-                early_iounmap(dst, len);
+                early_efi_unmap(src, len);
+                early_efi_unmap(dst, len);
         }
 }
 
@@ -79,16 +123,14 @@ static void early_efi_write_char(u32 *dst, unsigned char c, unsigned int h)
         }
 }
 
-static __init void
+static void
 early_efi_write(struct console *con, const char *str, unsigned int num)
 {
         struct screen_info *si;
-        unsigned long base;
         unsigned int len;
         const char *s;
         void *dst;
 
-        base = boot_params.screen_info.lfb_base;
         si = &boot_params.screen_info;
         len = si->lfb_linelength;
 
@@ -109,7 +151,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
                 for (h = 0; h < font->height; h++) {
                         unsigned int n, x;
 
-                        dst = early_ioremap(base + (efi_y + h) * len, len);
+                        dst = early_efi_map((efi_y + h) * len, len);
                         if (!dst)
                                 return;
 
@@ -123,7 +165,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num)
                                 s++;
                         }
 
-                        early_iounmap(dst, len);
+                        early_efi_unmap(dst, len);
                 }
 
                 num -= count;
@@ -179,6 +221,9 @@ static __init int early_efi_setup(struct console *con, char *options)
         for (i = 0; i < (yres - efi_y) / font->height; i++)
                 early_efi_scroll_up();
 
+        /* early_console_register will unset CON_BOOT in case ,keep */
+        if (!(con->flags & CON_BOOT))
+                early_efi_keep = true;
         return 0;
 }