[PATCH v2 0/6] arm64: Get rid of __early_init_dt_declare_initrd()

[PATCH v2 0/6] arm64: Get rid of __early_init_dt_declare_initrd()

[Florian Fainelli]

Hi all,

Changes in v2:

- get rid of ARCH_HAS_PHYS_INITRD and instead define
  phys_initrd_start/phys_initrd_size in init/do_mounts_initrd.c

- make __early_init_dt_declare_initrd() account for ARM64 specific
  behavior with __va() when having CONFIG_DEBUG_VM enabled

- consolidate early_initrd() command line parsing into
  init/do_mounts_initrd.c

Because phys_initrd_start/phys_initrd_size are now compiled in
ini/do_mounts_initrd.c which is only built with CONFIG_BLK_DEV_INITRD=y,
we need to be a bit careful about the uses throughout architecture
specific code.

Previous discussions/submissions list here:

v3:
https://www.spinics.net/lists/arm-kernel/msg683566.html
v2:
https://lkml.org/lkml/2018/10/25/4

Florian Fainelli (6):
  nds32: Remove phys_initrd_start and phys_initrd_size
  arch: Make phys_initrd_start and phys_initrd_size global variables
  of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT
  arm64: Utilize phys_initrd_start/phys_initrd_size
  of/fdt: Remove custom __early_init_dt_declare_initrd() implementation
  arch: Move initrd= parsing into do_mounts_initrd.c

 arch/arc/mm/init.c              | 25 +++++------------------
 arch/arm/mm/init.c              | 28 ++------------------------
 arch/arm64/include/asm/memory.h |  8 --------
 arch/arm64/mm/init.c            | 35 +++++++--------------------------
 arch/nds32/mm/init.c            |  2 --
 arch/unicore32/mm/init.c        | 24 +++++-----------------
 drivers/of/fdt.c                | 11 +++++++++--
 include/linux/initrd.h          |  3 +++
 init/do_mounts_initrd.c         | 20 +++++++++++++++++++
 9 files changed, 51 insertions(+), 105 deletions(-)

-- 
2.17.1

[PATCH v2 1/6] nds32: Remove phys_initrd_start and phys_initrd_size

[Florian Fainelli]

This will conflict with a subsequent change making phys_initrd_start and
phys_initrd_size global variables. nds32 does not make use of those nor
provides a suitable declarations so just get rid of them.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/nds32/mm/init.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/arch/nds32/mm/init.c b/arch/nds32/mm/init.c
index c713d2ad55dc..32f55a24ccbb 100644
--- a/arch/nds32/mm/init.c
+++ b/arch/nds32/mm/init.c
@@ -22,8 +22,6 @@
 DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 DEFINE_SPINLOCK(anon_alias_lock);
 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
-extern unsigned long phys_initrd_start;
-extern unsigned long phys_initrd_size;
 
 /*
  * empty_zero_page is a special page that is used for
-- 
2.17.1

[PATCH v2 2/6] arch: Make phys_initrd_start and phys_initrd_size global variables

[Florian Fainelli]

Make phys_initrd_start and phys_initrd_size global variables declared in
init/do_mounts_initrd.c such that we can later have generic code in
drivers/of/fdt.c populate those variables for us.

This requires both the ARM and unicore32 implementations to be properly
guarded against CONFIG_BLK_DEV_INITRD, and also initialize the variables
to the expected default values (unicore32).

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arm/mm/init.c       |  5 ++---
 arch/unicore32/mm/init.c | 10 +++++++---
 include/linux/initrd.h   |  3 +++
 init/do_mounts_initrd.c  |  3 +++
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 0cc8e04295a4..87d59a53861d 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -51,9 +51,7 @@ unsigned long __init __clear_cr(unsigned long mask)
 }
 #endif
 
-static phys_addr_t phys_initrd_start __initdata = 0;
-static unsigned long phys_initrd_size __initdata = 0;
-
+#ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
 	phys_addr_t start;
@@ -90,6 +88,7 @@ static int __init parse_tag_initrd2(const struct tag *tag)
 }
 
 __tagtable(ATAG_INITRD2, parse_tag_initrd2);
+#endif
 
 static void __init find_limits(unsigned long *min, unsigned long *max_low,
 			       unsigned long *max_high)
diff --git a/arch/unicore32/mm/init.c b/arch/unicore32/mm/init.c
index 8f8699e62bd5..f2f815d46846 100644
--- a/arch/unicore32/mm/init.c
+++ b/arch/unicore32/mm/init.c
@@ -31,9 +31,7 @@
 
 #include "mm.h"
 
-static unsigned long phys_initrd_start __initdata = 0x01000000;
-static unsigned long phys_initrd_size __initdata = SZ_8M;
-
+#ifdef CONFIG_BLK_DEV_INITRD
 static int __init early_initrd(char *p)
 {
 	unsigned long start, size;
@@ -49,6 +47,7 @@ static int __init early_initrd(char *p)
 	return 0;
 }
 early_param("initrd", early_initrd);
+#endif
 
 /*
  * This keeps memory configuration data used by a couple memory
@@ -157,6 +156,11 @@ void __init uc32_memblock_init(struct meminfo *mi)
 	memblock_reserve(__pa(_text), _end - _text);
 
 #ifdef CONFIG_BLK_DEV_INITRD
+	if (!phys_initrd_size) {
+		phys_initrd_start = 0x01000000;
+		phys_initrd_size = SZ_8M;
+	}
+
 	if (phys_initrd_size) {
 		memblock_reserve(phys_initrd_start, phys_initrd_size);
 
diff --git a/include/linux/initrd.h b/include/linux/initrd.h
index 84b423044088..14beaff9b445 100644
--- a/include/linux/initrd.h
+++ b/include/linux/initrd.h
@@ -21,4 +21,7 @@ extern int initrd_below_start_ok;
 extern unsigned long initrd_start, initrd_end;
 extern void free_initrd_mem(unsigned long, unsigned long);
 
+extern phys_addr_t phys_initrd_start;
+extern unsigned long phys_initrd_size;
+
 extern unsigned int real_root_dev;
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index d1a5d885ce13..45865b72f4ea 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -16,6 +16,9 @@ int initrd_below_start_ok;
 unsigned int real_root_dev;	/* do_proc_dointvec cannot handle kdev_t */
 static int __initdata mount_initrd = 1;
 
+phys_addr_t phys_initrd_start __initdata;
+unsigned long phys_initrd_size __initdata;
+
 static int __init no_initrd(char *str)
 {
 	mount_initrd = 0;
-- 
2.17.1

[PATCH v2 3/6] of/fdt: Populate phys_initrd_start/phys_initrd_size from FDT

[Florian Fainelli]

Now that we have central and global variables holding the physical
address and size of the initrd, we can have
early_init_dt_check_for_initrd() populate
phys_initrd_start/phys_initrd_size for us.

This allows us to remove a chunk of code from arch/arm/mm/init.c
introduced with commit 65939301acdb ("arm: set initrd_start/initrd_end
for fdt scan").

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arm/mm/init.c | 6 ------
 drivers/of/fdt.c   | 2 ++
 2 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 87d59a53861d..4bfa08e27319 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -236,12 +236,6 @@ static void __init arm_initrd_init(void)
 	phys_addr_t start;
 	unsigned long size;
 
-	/* FDT scan will populate initrd_start */
-	if (initrd_start && !phys_initrd_size) {
-		phys_initrd_start = __virt_to_phys(initrd_start);
-		phys_initrd_size = initrd_end - initrd_start;
-	}
-
 	initrd_start = initrd_end = 0;
 
 	if (!phys_initrd_size)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 76c83c1ffeda..e34cb49231b5 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -925,6 +925,8 @@ static void __init early_init_dt_check_for_initrd(unsigned long node)
 	end = of_read_number(prop, len/4);
 
 	__early_init_dt_declare_initrd(start, end);
+	phys_initrd_start = start;
+	phys_initrd_size = end - start;
 
 	pr_debug("initrd_start=0x%llx  initrd_end=0x%llx\n",
 		 (unsigned long long)start, (unsigned long long)end);
-- 
2.17.1

[PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

[Florian Fainelli]

ARM64 is the only architecture that re-defines
__early_init_dt_declare_initrd() in order for that function to populate
initrd_start/initrd_end with physical addresses instead of virtual
addresses. Instead of having an override we can leverage
drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
populate those variables for us.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arm64/mm/init.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 3cf87341859f..e95cee656a55 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
 	if (*endp == ',') {
 		size = memparse(endp + 1, NULL);
 
-		initrd_start = start;
-		initrd_end = start + size;
+		phys_initrd_start = start;
+		phys_initrd_size = size;
 	}
 	return 0;
 }
@@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
 		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
 	}
 
-	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
+	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
 		/*
 		 * Add back the memory we just removed if it results in the
 		 * initrd to become inaccessible via the linear mapping.
 		 * Otherwise, this is a no-op
 		 */
-		u64 base = initrd_start & PAGE_MASK;
-		u64 size = PAGE_ALIGN(initrd_end) - base;
+		u64 base = phys_initrd_start & PAGE_MASK;
+		u64 size = PAGE_ALIGN(phys_initrd_size);
 
 		/*
 		 * We can only add back the initrd memory if we don't end up
@@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
 	 */
 	memblock_reserve(__pa_symbol(_text), _end - _text);
 #ifdef CONFIG_BLK_DEV_INITRD
-	if (initrd_start) {
-		memblock_reserve(initrd_start, initrd_end - initrd_start);
-
-		/* the generic initrd code expects virtual addresses */
-		initrd_start = __phys_to_virt(initrd_start);
-		initrd_end = __phys_to_virt(initrd_end);
-	}
+	/* the generic initrd code expects virtual addresses */
+	initrd_start = __phys_to_virt(phys_initrd_start);
+	initrd_end = initrd_start + phys_initrd_size;
+	initrd_below_start_ok = 0;
 #endif
 
 	early_init_fdt_scan_reserved_mem();
-- 
2.17.1

[PATCH v2 5/6] of/fdt: Remove custom __early_init_dt_declare_initrd() implementation

[Florian Fainelli]

Now that ARM64 uses phys_initrd_start/phys_initrd_size, we can get rid
of its custom __early_init_dt_declare_initrd() which causes a fair
amount of objects rebuild when changing CONFIG_BLK_DEV_INITRD. In order
to make sure ARM64 does not produce a BUG() when VM debugging is turned
on though, we must avoid early calls to __va() which is what
__early_init_dt_declare_initrd() does and wrap this around to avoid
running that code on ARM64.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arm64/include/asm/memory.h | 8 --------
 drivers/of/fdt.c                | 9 +++++++--
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index b96442960aea..dc3ca21ba240 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -168,14 +168,6 @@
 #define IOREMAP_MAX_ORDER	(PMD_SHIFT)
 #endif
 
-#ifdef CONFIG_BLK_DEV_INITRD
-#define __early_init_dt_declare_initrd(__start, __end)			\
-	do {								\
-		initrd_start = (__start);				\
-		initrd_end = (__end);					\
-	} while (0)
-#endif
-
 #ifndef __ASSEMBLY__
 
 #include <linux/bitops.h>
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index e34cb49231b5..f2b5becae96a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -892,15 +892,20 @@ const void * __init of_flat_dt_match_machine(const void *default_match,
 }
 
 #ifdef CONFIG_BLK_DEV_INITRD
-#ifndef __early_init_dt_declare_initrd
 static void __early_init_dt_declare_initrd(unsigned long start,
 					   unsigned long end)
 {
+	/* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
+	 * enabled since __va() is called too early. ARM64 does make use
+	 * of phys_initrd_start/phys_initrd_size so we can skip this
+	 * conversion.
+	 */
+#if (!IS_ENABLED(CONFIG_ARM64))
 	initrd_start = (unsigned long)__va(start);
 	initrd_end = (unsigned long)__va(end);
 	initrd_below_start_ok = 1;
-}
 #endif
+}
 
 /**
  * early_init_dt_check_for_initrd - Decode initrd location from flat tree
-- 
2.17.1

[PATCH v2 6/6] arch: Move initrd= parsing into do_mounts_initrd.c

[Florian Fainelli]

ARC, ARM, ARM64 and Unicore32 are all capable of parsing the "initrd="
command line parameter to allow specifying the physical address and size
of an initrd. Move that parsing into init/do_mounts_initrd.c such that
we no longer duplicate that logic.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 arch/arc/mm/init.c       | 25 +++++--------------------
 arch/arm/mm/init.c       | 17 -----------------
 arch/arm64/mm/init.c     | 18 ------------------
 arch/unicore32/mm/init.c | 18 ------------------
 init/do_mounts_initrd.c  | 17 +++++++++++++++++
 5 files changed, 22 insertions(+), 73 deletions(-)

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index ba145065c579..369d3d699929 100644
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -79,24 +79,6 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
 		base, TO_MB(size), !in_use ? "Not used":"");
 }
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-	unsigned long start, size;
-	char *endp;
-
-	start = memparse(p, &endp);
-	if (*endp == ',') {
-		size = memparse(endp + 1, NULL);
-
-		initrd_start = (unsigned long)__va(start);
-		initrd_end = (unsigned long)__va(start + size);
-	}
-	return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 /*
  * First memory setup routine called from setup_arch()
  * 1. setup swapper's mm @init_mm
@@ -141,8 +123,11 @@ void __init setup_arch_memory(void)
 	memblock_reserve(low_mem_start, __pa(_end) - low_mem_start);
 
 #ifdef CONFIG_BLK_DEV_INITRD
-	if (initrd_start)
-		memblock_reserve(__pa(initrd_start), initrd_end - initrd_start);
+	if (phys_initrd_size) {
+		memblock_reserve(phys_initrd_start, phys_initrd_size);
+		initrd_start = __va(phys_initrd_start);
+		initrd_end = initrd_start + phys_initrd_size;
+	}
 #endif
 
 	early_init_fdt_reserve_self();
diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index 4bfa08e27319..58ec68709606 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -52,23 +52,6 @@ unsigned long __init __clear_cr(unsigned long mask)
 #endif
 
 #ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-	phys_addr_t start;
-	unsigned long size;
-	char *endp;
-
-	start = memparse(p, &endp);
-	if (*endp == ',') {
-		size = memparse(endp + 1, NULL);
-
-		phys_initrd_start = start;
-		phys_initrd_size = size;
-	}
-	return 0;
-}
-early_param("initrd", early_initrd);
-
 static int __init parse_tag_initrd(const struct tag *tag)
 {
 	pr_warn("ATAG_INITRD is deprecated; "
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index e95cee656a55..9045afacd10b 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -62,24 +62,6 @@
 s64 memstart_addr __ro_after_init = -1;
 phys_addr_t arm64_dma_phys_limit __ro_after_init;
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-	unsigned long start, size;
-	char *endp;
-
-	start = memparse(p, &endp);
-	if (*endp == ',') {
-		size = memparse(endp + 1, NULL);
-
-		phys_initrd_start = start;
-		phys_initrd_size = size;
-	}
-	return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 #ifdef CONFIG_KEXEC_CORE
 /*
  * reserve_crashkernel() - reserves memory for crash kernel
diff --git a/arch/unicore32/mm/init.c b/arch/unicore32/mm/init.c
index f2f815d46846..99acdb829a7e 100644
--- a/arch/unicore32/mm/init.c
+++ b/arch/unicore32/mm/init.c
@@ -31,24 +31,6 @@
 
 #include "mm.h"
 
-#ifdef CONFIG_BLK_DEV_INITRD
-static int __init early_initrd(char *p)
-{
-	unsigned long start, size;
-	char *endp;
-
-	start = memparse(p, &endp);
-	if (*endp == ',') {
-		size = memparse(endp + 1, NULL);
-
-		phys_initrd_start = start;
-		phys_initrd_size = size;
-	}
-	return 0;
-}
-early_param("initrd", early_initrd);
-#endif
-
 /*
  * This keeps memory configuration data used by a couple memory
  * initialization functions, as well as show_mem() for the skipping
diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index 45865b72f4ea..732d21f4a637 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -27,6 +27,23 @@ static int __init no_initrd(char *str)
 
 __setup("noinitrd", no_initrd);
 
+static int __init early_initrd(char *p)
+{
+	phys_addr_t start;
+	unsigned long size;
+	char *endp;
+
+	start = memparse(p, &endp);
+	if (*endp == ',') {
+		size = memparse(endp + 1, NULL);
+
+		phys_initrd_start = start;
+		phys_initrd_size = size;
+	}
+	return 0;
+}
+early_param("initrd", early_initrd);
+
 static int init_linuxrc(struct subprocess_info *info, struct cred *new)
 {
 	ksys_unshare(CLONE_FS | CLONE_FILES);
-- 
2.17.1

[PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

[Mike Rapoport]

On Tue, Oct 30, 2018 at 04:07:19PM -0700, Florian Fainelli wrote:
> ARM64 is the only architecture that re-defines
> __early_init_dt_declare_initrd() in order for that function to populate
> initrd_start/initrd_end with physical addresses instead of virtual
> addresses. Instead of having an override we can leverage
> drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
> populate those variables for us.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
>  arch/arm64/mm/init.c | 21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 3cf87341859f..e95cee656a55 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
>  	if (*endp == ',') {
>  		size = memparse(endp + 1, NULL);
>  
> -		initrd_start = start;
> -		initrd_end = start + size;
> +		phys_initrd_start = start;
> +		phys_initrd_size = size;
>  	}
>  	return 0;
>  }
> @@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
>  		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
>  	}
>  
> -	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
> +	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
>  		/*
>  		 * Add back the memory we just removed if it results in the
>  		 * initrd to become inaccessible via the linear mapping.
>  		 * Otherwise, this is a no-op
>  		 */
> -		u64 base = initrd_start & PAGE_MASK;
> -		u64 size = PAGE_ALIGN(initrd_end) - base;
> +		u64 base = phys_initrd_start & PAGE_MASK;
> +		u64 size = PAGE_ALIGN(phys_initrd_size);
>  
>  		/*
>  		 * We can only add back the initrd memory if we don't end up
> @@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
>  	 */
>  	memblock_reserve(__pa_symbol(_text), _end - _text);
>  #ifdef CONFIG_BLK_DEV_INITRD
> -	if (initrd_start) {

There may be no initrd at all, so the condition here would rather become

	if (phys_initrd_start)

> -		memblock_reserve(initrd_start, initrd_end - initrd_start);
> -
> -		/* the generic initrd code expects virtual addresses */
> -		initrd_start = __phys_to_virt(initrd_start);
> -		initrd_end = __phys_to_virt(initrd_end);
> -	}
> +	/* the generic initrd code expects virtual addresses */
> +	initrd_start = __phys_to_virt(phys_initrd_start);
> +	initrd_end = initrd_start + phys_initrd_size;
> +	initrd_below_start_ok = 0;
>  #endif

I also wonder what is the reason to keep memstart_addr randomization and
initrd setup interleaved?

What we have now is roughly:

1) set memstart_addr
2) enforce memory_limit
3) reserve initrd
4) randomize memstart_addr
5) reserve text + data
6) reserve initrd again and set virtual addresses of initrd_{start,end}

Maybe it's possible to merge (3) into (6) ?

>  	early_init_fdt_scan_reserved_mem();
> -- 
> 2.17.1
> 

-- 
Sincerely yours,
Mike.

[PATCH v2 5/6] of/fdt: Remove custom __early_init_dt_declare_initrd() implementation

[Rob Herring]

On Tue, Oct 30, 2018 at 6:07 PM Florian Fainelli <f.fainelli@gmail.com> wrote:
>
> Now that ARM64 uses phys_initrd_start/phys_initrd_size, we can get rid
> of its custom __early_init_dt_declare_initrd() which causes a fair
> amount of objects rebuild when changing CONFIG_BLK_DEV_INITRD. In order
> to make sure ARM64 does not produce a BUG() when VM debugging is turned
> on though, we must avoid early calls to __va() which is what
> __early_init_dt_declare_initrd() does and wrap this around to avoid
> running that code on ARM64.
>
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
>  arch/arm64/include/asm/memory.h | 8 --------
>  drivers/of/fdt.c                | 9 +++++++--
>  2 files changed, 7 insertions(+), 10 deletions(-)
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index b96442960aea..dc3ca21ba240 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -168,14 +168,6 @@
>  #define IOREMAP_MAX_ORDER      (PMD_SHIFT)
>  #endif
>
> -#ifdef CONFIG_BLK_DEV_INITRD
> -#define __early_init_dt_declare_initrd(__start, __end)                 \
> -       do {                                                            \
> -               initrd_start = (__start);                               \
> -               initrd_end = (__end);                                   \
> -       } while (0)
> -#endif
> -
>  #ifndef __ASSEMBLY__
>
>  #include <linux/bitops.h>
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index e34cb49231b5..f2b5becae96a 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -892,15 +892,20 @@ const void * __init of_flat_dt_match_machine(const void *default_match,
>  }
>
>  #ifdef CONFIG_BLK_DEV_INITRD
> -#ifndef __early_init_dt_declare_initrd
>  static void __early_init_dt_declare_initrd(unsigned long start,
>                                            unsigned long end)
>  {
> +       /* ARM64 would cause a BUG to occur here when CONFIG_DEBUG_VM is
> +        * enabled since __va() is called too early. ARM64 does make use
> +        * of phys_initrd_start/phys_initrd_size so we can skip this
> +        * conversion.
> +        */
> +#if (!IS_ENABLED(CONFIG_ARM64))

Use 'if' not '#if'. Use C code rather than preprocessor whenever possible.

>         initrd_start = (unsigned long)__va(start);
>         initrd_end = (unsigned long)__va(end);
>         initrd_below_start_ok = 1;
> -}
>  #endif
> +}
>
>  /**
>   * early_init_dt_check_for_initrd - Decode initrd location from flat tree
> --
> 2.17.1
>

[PATCH v2 4/6] arm64: Utilize phys_initrd_start/phys_initrd_size

[Florian Fainelli]

On 10/31/18 12:03 AM, Mike Rapoport wrote:
> On Tue, Oct 30, 2018 at 04:07:19PM -0700, Florian Fainelli wrote:
>> ARM64 is the only architecture that re-defines
>> __early_init_dt_declare_initrd() in order for that function to populate
>> initrd_start/initrd_end with physical addresses instead of virtual
>> addresses. Instead of having an override we can leverage
>> drivers/of/fdt.c populating phys_initrd_start/phys_initrd_size to
>> populate those variables for us.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
>> ---
>>  arch/arm64/mm/init.c | 21 +++++++++------------
>>  1 file changed, 9 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
>> index 3cf87341859f..e95cee656a55 100644
>> --- a/arch/arm64/mm/init.c
>> +++ b/arch/arm64/mm/init.c
>> @@ -72,8 +72,8 @@ static int __init early_initrd(char *p)
>>  	if (*endp == ',') {
>>  		size = memparse(endp + 1, NULL);
>>  
>> -		initrd_start = start;
>> -		initrd_end = start + size;
>> +		phys_initrd_start = start;
>> +		phys_initrd_size = size;
>>  	}
>>  	return 0;
>>  }
>> @@ -408,14 +408,14 @@ void __init arm64_memblock_init(void)
>>  		memblock_add(__pa_symbol(_text), (u64)(_end - _text));
>>  	}
>>  
>> -	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
>> +	if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) {
>>  		/*
>>  		 * Add back the memory we just removed if it results in the
>>  		 * initrd to become inaccessible via the linear mapping.
>>  		 * Otherwise, this is a no-op
>>  		 */
>> -		u64 base = initrd_start & PAGE_MASK;
>> -		u64 size = PAGE_ALIGN(initrd_end) - base;
>> +		u64 base = phys_initrd_start & PAGE_MASK;
>> +		u64 size = PAGE_ALIGN(phys_initrd_size);
>>  
>>  		/*
>>  		 * We can only add back the initrd memory if we don't end up
>> @@ -460,13 +460,10 @@ void __init arm64_memblock_init(void)
>>  	 */
>>  	memblock_reserve(__pa_symbol(_text), _end - _text);
>>  #ifdef CONFIG_BLK_DEV_INITRD
>> -	if (initrd_start) {
> 
> There may be no initrd at all, so the condition here would rather become
> 
> 	if (phys_initrd_start)

Or use phys_initrd_size, which would be consistent with how other
architectures typically test for this.

> 
>> -		memblock_reserve(initrd_start, initrd_end - initrd_start);
>> -
>> -		/* the generic initrd code expects virtual addresses */
>> -		initrd_start = __phys_to_virt(initrd_start);
>> -		initrd_end = __phys_to_virt(initrd_end);
>> -	}
>> +	/* the generic initrd code expects virtual addresses */
>> +	initrd_start = __phys_to_virt(phys_initrd_start);
>> +	initrd_end = initrd_start + phys_initrd_size;
>> +	initrd_below_start_ok = 0;
>>  #endif
> 
> I also wonder what is the reason to keep memstart_addr randomization and
> initrd setup interleaved?
> 
> What we have now is roughly:
> 
> 1) set memstart_addr
> 2) enforce memory_limit
> 3) reserve initrd
> 4) randomize memstart_addr
> 5) reserve text + data
> 6) reserve initrd again and set virtual addresses of initrd_{start,end}
> 
> Maybe it's possible to merge (3) into (6) ?

That's kind of orthogonal to this patch series, but it's a valid
question, not sure I would want to tackle that just now though :)
-- 
Florian