From 03b601aff130616e730ac81cc6f448f2bd2bc192 Mon Sep 17 00:00:00 2001 From: Tom Rini Date: Thu, 10 Dec 2020 21:27:36 -0500 Subject: libfdt: Internally perform potentially unaligned loads Commits 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. On further discussion, while there are potential cases where we could be used on platforms that do not fixup unaligned reads for us, making this choice the default is very expensive in terms of binary size and access time. To address this, introduce and use new fdt{32,64}_ld_ functions that call fdt{32,64}_to_cpu() as was done prior to the above mentioned commits. Leave the existing load functions as unaligned-safe and include comments in both cases. Reviewed-by: Rob Herring Signed-off-by: Tom Rini Message-Id: <20201211022736.31657-1-trini@konsulko.com> Tested-by: John Paul Adrian Glaubitz Signed-off-by: David Gibson --- cpukit/dtc/libfdt/fdt_ro.c | 20 ++++++++++---------- cpukit/dtc/libfdt/libfdt_internal.h | 19 +++++++++++++++++++ 2 files changed, 29 insertions(+), 10 deletions(-) (limited to 'cpukit/dtc/libfdt') diff --git a/cpukit/dtc/libfdt/fdt_ro.c b/cpukit/dtc/libfdt/fdt_ro.c index 91cc6fefe3..17584da257 100644 --- a/cpukit/dtc/libfdt/fdt_ro.c +++ b/cpukit/dtc/libfdt/fdt_ro.c @@ -181,8 +181,8 @@ int fdt_get_mem_rsv(const void *fdt, int n, uint64_t *address, uint64_t *size) if (!can_assume(VALID_INPUT) && !re) return -FDT_ERR_BADOFFSET; - *address = fdt64_ld(&re->address); - *size = fdt64_ld(&re->size); + *address = fdt64_ld_(&re->address); + *size = fdt64_ld_(&re->size); return 0; } @@ -192,7 +192,7 @@ 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_ld_(&re->size) == 0) return i; } return -FDT_ERR_TRUNCATED; @@ -370,7 +370,7 @@ 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_ld_(&prop->len); return prop; } @@ -408,7 +408,7 @@ 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_ld_(&prop->nameoff), name, namelen)) { if (poffset) *poffset = offset; @@ -461,7 +461,7 @@ const void *fdt_getprop_namelen(const void *fdt, int nodeoffset, /* Handle realignment */ if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 && - (poffset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8) + (poffset + sizeof(*prop)) % 8 && fdt32_ld_(&prop->len) >= 8) return prop->data + 4; return prop->data; } @@ -479,7 +479,7 @@ const void *fdt_getprop_by_offset(const void *fdt, int offset, int namelen; if (!can_assume(VALID_INPUT)) { - name = fdt_get_string(fdt, fdt32_ld(&prop->nameoff), + name = fdt_get_string(fdt, fdt32_ld_(&prop->nameoff), &namelen); if (!name) { if (lenp) @@ -488,13 +488,13 @@ 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_ld_(&prop->nameoff)); } } /* Handle realignment */ if (!can_assume(LATEST) && fdt_version(fdt) < 0x10 && - (offset + sizeof(*prop)) % 8 && fdt32_ld(&prop->len) >= 8) + (offset + sizeof(*prop)) % 8 && fdt32_ld_(&prop->len) >= 8) return prop->data + 4; return prop->data; } @@ -519,7 +519,7 @@ uint32_t fdt_get_phandle(const void *fdt, int nodeoffset) return 0; } - return fdt32_ld(php); + return fdt32_ld_(php); } const char *fdt_get_alias_namelen(const void *fdt, diff --git a/cpukit/dtc/libfdt/libfdt_internal.h b/cpukit/dtc/libfdt/libfdt_internal.h index d4e0bd49c0..8b580aa507 100644 --- a/cpukit/dtc/libfdt/libfdt_internal.h +++ b/cpukit/dtc/libfdt/libfdt_internal.h @@ -46,6 +46,25 @@ static inline struct fdt_reserve_entry *fdt_mem_rsv_w_(void *fdt, int n) return (void *)(uintptr_t)fdt_mem_rsv_(fdt, n); } +/* + * Internal helpers to access tructural elements of the device tree blob + * (rather than for exaple reading integers from within property values). We + * assume that we are either given a naturally aligned address for the platform + * or if we are not, we are on a platform where unaligned memory reads will be + * handled in a graceful manner. If this is not the case there are _unaligned + * versions of these functions that follow and can be used. + * + */ +static inline uint32_t fdt32_ld_(const fdt32_t *p) +{ + return fdt32_to_cpu(*p); +} + +static inline uint64_t fdt64_ld_(const fdt64_t *p) +{ + return fdt64_to_cpu(*p); +} + #define FDT_SW_MAGIC (~FDT_MAGIC) /**********************************************************************/ -- cgit v1.2.3