diff mbox series

libfdt: Revert 6dcb8ba4 from upstream libfdt

Message ID 20200127151909.21335-1-trini@konsulko.com
State Superseded
Headers show
Series libfdt: Revert 6dcb8ba4 from upstream libfdt | expand

Commit Message

Tom Rini Jan. 27, 2020, 3:19 p.m. UTC 
In upstream libfdt, 6dcb8ba4 "libfdt: Add helpers for accessing
unaligned words" introduced changes to support unaligned reads for ARM
platforms and 11738cf01f15 "libfdt: Don't use memcpy to handle unaligned
reads on ARM" improved the performance of these helpers.

In practice however, this only occurs when the user has forced the
device tree to be placed in memory in a non-aligned way, which in turn
violates both our rules and the Linux Kernel rules for how things must
reside in memory to function.

This "in practice" part is important as handling these other cases adds
visible (1 second or more) delay to boot in what would be considered the
fast path of the code.

Cc: Patrice CHOTARD <patrice.chotard at st.com>
Cc: Patrick DELAUNAY <patrick.delaunay at st.com>
Link: https://www.spinics.net/lists/devicetree-compiler/msg02972.html
Signed-off-by: Tom Rini <trini at konsulko.com>
---
 lib/libfdt/fdt_ro.c         | 20 ++++++++++----------
 scripts/dtc/libfdt/fdt_ro.c | 20 ++++++++++----------
 scripts/dtc/libfdt/libfdt.h | 33 +--------------------------------
 3 files changed, 21 insertions(+), 52 deletions(-)

Comments

Tom Rini Jan. 27, 2020, 3:20 p.m. UTC | #1 
On Mon, Jan 27, 2020 at 10:19:09AM -0500, Tom Rini wrote:

> In upstream libfdt, 6dcb8ba4 "libfdt: Add helpers for accessing
> unaligned words" introduced changes to support unaligned reads for ARM
> platforms and 11738cf01f15 "libfdt: Don't use memcpy to handle unaligned
> reads on ARM" improved the performance of these helpers.
> 
> In practice however, this only occurs when the user has forced the
> device tree to be placed in memory in a non-aligned way, which in turn
> violates both our rules and the Linux Kernel rules for how things must
> reside in memory to function.
> 
> This "in practice" part is important as handling these other cases adds
> visible (1 second or more) delay to boot in what would be considered the
> fast path of the code.
> 
> Cc: Patrice CHOTARD <patrice.chotard at st.com>
> Cc: Patrick DELAUNAY <patrick.delaunay at st.com>
> Link: https://www.spinics.net/lists/devicetree-compiler/msg02972.html
> Signed-off-by: Tom Rini <trini at konsulko.com>

I can see now I didn't quite catch everything, oops.  That's what I get
for posting and then testing.  v2 shortly, sorry all.
diff mbox series

Patch

diff --git a/lib/libfdt/fdt_ro.c b/lib/libfdt/fdt_ro.c
index 560041b603e1..03fa60583acc 100644
--- a/lib/libfdt/fdt_ro.c
+++ b/lib/libfdt/fdt_ro.c
@@ -183,8 +183,8 @@  int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
 	if (fdt_chk_extra() && !re)
 		return -FDT_ERR_BADOFFSET;
 
-	*address = fdt64_ld(&re->address);
-	*size = fdt64_ld(&re->size);
+	*address = fdt64_to_cpu(re->address);
+	*size = fdt64_to_cpu(re->size);
 	return 0;
 }
 
@@ -194,7 +194,7 @@  int fdt_num_mem_rsv(const void *fdt)
 	const struct fdt_reserve_entry *re;
 
 	for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
-		if (fdt64_ld(&re->size) == 0)
+		if (fdt64_to_cpu(re->size) == 0)
 			return i;
 	}
 	return -FDT_ERR_TRUNCATED;
@@ -372,7 +372,7 @@  static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
 	prop = fdt_offset_ptr_(fdt, offset);
 
 	if (lenp)
-		*lenp = fdt32_ld(&prop->len);
+		*lenp = fdt32_to_cpu(prop->len);
 
 	return prop;
 }
@@ -410,7 +410,7 @@  static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
 			offset = -FDT_ERR_INTERNAL;
 			break;
 		}
-		if (fdt_string_eq_(fdt, fdt32_ld(&prop->nameoff),
+		if (fdt_string_eq_(fdt, fdt32_to_cpu(prop->nameoff),
 				   name, namelen)) {
 			if (poffset)
 				*poffset = offset;
@@ -463,7 +463,7 @@  const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
 
 	/* Handle realignment */
 	if (fdt_chk_version() && fdt_version(fdt) < 0x10 &&
-	    (poffset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+	    (poffset + sizeof(*prop)) % 8 && fdt32_to_cpu(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -481,7 +481,7 @@  const void *fdt_getprop_by_offset(const void *fdt, int offset,
 		int namelen;
 
 		if (fdt_chk_extra()) {
-			name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff),
+			name = fdt_get_string(fdt, fdt32_to_cpu(&prop->nameoff),
 					      &namelen);
 			if (!name) {
 				if (lenp)
@@ -490,13 +490,13 @@  const void *fdt_getprop_by_offset(const void *fdt, int offset,
 			}
 			*namep = name;
 		} else {
-			*namep = fdt_string(fdt, fdt32_ld(&prop->nameoff));
+			*namep = fdt_string(fdt, fdt32_to_cpu(&prop->nameoff));
 		}
 	}
 
 	/* Handle realignment */
 	if (fdt_chk_version() && fdt_version(fdt) < 0x10 &&
-	    (offset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+	    (offset + sizeof(*prop)) % 8 && fdt32_to_cpu(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -521,7 +521,7 @@  uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
 			return 0;
 	}
 
-	return fdt32_ld(php);
+	return fdt32_to_cpu(*php);
 }
 
 const char *fdt_get_alias_namelen(const void *fdt,
diff --git a/scripts/dtc/libfdt/fdt_ro.c b/scripts/dtc/libfdt/fdt_ro.c
index e398815485d6..91a69009d698 100644
--- a/scripts/dtc/libfdt/fdt_ro.c
+++ b/scripts/dtc/libfdt/fdt_ro.c
@@ -179,8 +179,8 @@  int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size)
 	if (fdt_chk_extra() && !re)
 		return -FDT_ERR_BADOFFSET;
 
-	*address = fdt64_ld(&re->address);
-	*size = fdt64_ld(&re->size);
+	*address = fdt64_to_cpu(re->address);
+	*size = fdt64_to_cpu(re->size);
 	return 0;
 }
 
@@ -190,7 +190,7 @@  int fdt_num_mem_rsv(const void *fdt)
 	const struct fdt_reserve_entry *re;
 
 	for (i = 0; (re = fdt_mem_rsv(fdt, i)) != NULL; i++) {
-		if (fdt64_ld(&re->size) == 0)
+		if (fdt64_to_cpu(re->size) == 0)
 			return i;
 	}
 	return -FDT_ERR_TRUNCATED;
@@ -368,7 +368,7 @@  static const struct fdt_property *fdt_get_property_by_offset_(const void *fdt,
 	prop = fdt_offset_ptr_(fdt, offset);
 
 	if (lenp)
-		*lenp = fdt32_ld(&prop->len);
+		*lenp = fdt32_to_cpu(prop->len);
 
 	return prop;
 }
@@ -406,7 +406,7 @@  static const struct fdt_property *fdt_get_property_namelen_(const void *fdt,
 			offset = -FDT_ERR_INTERNAL;
 			break;
 		}
-		if (fdt_string_eq_(fdt, fdt32_ld(&prop->nameoff),
+		if (fdt_string_eq_(fdt, fdt32_to_cpu(prop->nameoff),
 				   name, namelen)) {
 			if (poffset)
 				*poffset = offset;
@@ -459,7 +459,7 @@  const void *fdt_getprop_namelen(const void *fdt, int nodeoffset,
 
 	/* Handle realignment */
 	if (fdt_chk_version() && fdt_version(fdt) < 0x10 &&
-	    (poffset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+	    (poffset + sizeof(*prop)) % 8 && fdt32_to_cpu(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -477,7 +477,7 @@  const void *fdt_getprop_by_offset(const void *fdt, int offset,
 		int namelen;
 
 		if (fdt_chk_extra()) {
-			name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff),
+			name = fdt_get_string(fdt, fdt32_to_cpu(&prop->nameoff),
 					      &namelen);
 			if (!name) {
 				if (lenp)
@@ -486,13 +486,13 @@  const void *fdt_getprop_by_offset(const void *fdt, int offset,
 			}
 			*namep = name;
 		} else {
-			*namep = fdt_string(fdt, fdt32_ld(&prop->nameoff));
+			*namep = fdt_string(fdt, fdt32_to_cpu(&prop->nameoff));
 		}
 	}
 
 	/* Handle realignment */
 	if (fdt_chk_version() && fdt_version(fdt) < 0x10 &&
-	    (offset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8)
+	    (offset + sizeof(*prop)) % 8 && fdt32_to_cpu(&prop->len) >= 8)
 		return prop->data + 4;
 	return prop->data;
 }
@@ -517,7 +517,7 @@  uint32_t fdt_get_phandle(const void *fdt, int nodeoffset)
 			return 0;
 	}
 
-	return fdt32_ld(php);
+	return fdt32_to_cpu(*php);
 }
 
 const char *fdt_get_alias_namelen(const void *fdt,
diff --git a/scripts/dtc/libfdt/libfdt.h b/scripts/dtc/libfdt/libfdt.h
index 36fadcdea516..fa63fffe28e9 100644
--- a/scripts/dtc/libfdt/libfdt.h
+++ b/scripts/dtc/libfdt/libfdt.h
@@ -117,23 +117,6 @@  static inline void *fdt_offset_ptr_w(void *fdt, int offset, int checklen)
 
 uint32_t fdt_next_tag(const void *fdt, int offset, int *nextoffset);
 
-/*
- * Alignment helpers:
- *     These helpers access words from a device tree blob.  They're
- *     built to work even with unaligned pointers on platforms (ike
- *     ARM) that don't like unaligned loads and stores
- */
-
-static inline uint32_t fdt32_ld(const fdt32_t *p)
-{
-	const uint8_t *bp = (const uint8_t *)p;
-
-	return ((uint32_t)bp[0] << 24)
-		| ((uint32_t)bp[1] << 16)
-		| ((uint32_t)bp[2] << 8)
-		| bp[3];
-}
-
 static inline void fdt32_st(void *property, uint32_t value)
 {
 	uint8_t *bp = (uint8_t *)property;
@@ -144,20 +127,6 @@  static inline void fdt32_st(void *property, uint32_t value)
 	bp[3] = value & 0xff;
 }
 
-static inline uint64_t fdt64_ld(const fdt64_t *p)
-{
-	const uint8_t *bp = (const uint8_t *)p;
-
-	return ((uint64_t)bp[0] << 56)
-		| ((uint64_t)bp[1] << 48)
-		| ((uint64_t)bp[2] << 40)
-		| ((uint64_t)bp[3] << 32)
-		| ((uint64_t)bp[4] << 24)
-		| ((uint64_t)bp[5] << 16)
-		| ((uint64_t)bp[6] << 8)
-		| bp[7];
-}
-
 static inline void fdt64_st(void *property, uint64_t value)
 {
 	uint8_t *bp = (uint8_t *)property;
@@ -232,7 +201,7 @@  int fdt_next_subnode(const void *fdt, int offset);
 /* General functions                                                  */
 /**********************************************************************/
 #define fdt_get_header(fdt, field) \
-	(fdt32_ld(&((const struct fdt_header *)(fdt))->field))
+	(fdt32_to_cpu(((const struct fdt_header *)(fdt))->field))
 #define fdt_magic(fdt)			(fdt_get_header(fdt, magic))
 #define fdt_totalsize(fdt)		(fdt_get_header(fdt, totalsize))
 #define fdt_off_dt_struct(fdt)		(fdt_get_header(fdt, off_dt_struct))