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[24.6.192.50]) by smtp.gmail.com with ESMTPSA id i185-v6sm7551888pfg.89.2018.09.13.18.42.35 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 13 Sep 2018 18:42:37 -0700 (PDT) Subject: Re: [PATCH v14 06/16] of/fdt: add helper functions for handling properties To: AKASHI Takahiro , catalin.marinas@arm.com, will.deacon@arm.com, dhowells@redhat.com, vgoyal@redhat.com, herbert@gondor.apana.org.au, davem@davemloft.net, dyoung@redhat.com, bhe@redhat.com, arnd@arndb.de, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, prudo@linux.ibm.com, ard.biesheuvel@linaro.org, james.morse@arm.com, bhsharma@redhat.com, kexec@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Rob Herring References: <20180907080040.4967-1-takahiro.akashi@linaro.org> <20180910023819.GA30795@linaro.org> From: Frank Rowand Message-ID: <59d0bc6f-ab71-eb21-d438-da3cd09aaa79@gmail.com> Date: Thu, 13 Sep 2018 18:42:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180910023819.GA30795@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/09/18 19:38, AKASHI Takahiro wrote: > Frank, > > Thank you for the comments. I will address all of them, but > have one question: > > On Fri, Sep 07, 2018 at 12:53:58PM -0700, Frank Rowand wrote: >> On 09/07/18 01:00, AKASHI Takahiro wrote: >>> These functions will be used later to handle kexec-specific properties >>> in arm64's kexec_file implementation. >>> >>> Signed-off-by: AKASHI Takahiro >>> Cc: Rob Herring >>> Cc: Frank Rowand >>> --- >>> drivers/of/fdt.c | 62 ++++++++++++++++++++++++++++++++++++++++-- >>> include/linux/of_fdt.h | 10 +++++-- >>> 2 files changed, 68 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c >>> index 800ad252cf9c..dc960cea1355 100644 >>> --- a/drivers/of/fdt.c >>> +++ b/drivers/of/fdt.c >>> @@ -25,6 +25,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> >>> #include /* for COMMAND_LINE_SIZE */ >>> #include >>> @@ -537,8 +538,8 @@ void *of_fdt_unflatten_tree(const unsigned long *blob, >>> EXPORT_SYMBOL_GPL(of_fdt_unflatten_tree); >>> >>> /* Everything below here references initial_boot_params directly. */ >>> -int __initdata dt_root_addr_cells; >>> -int __initdata dt_root_size_cells; >>> +int dt_root_addr_cells; >>> +int dt_root_size_cells; >>> >>> void *initial_boot_params; >>> >>> @@ -1323,3 +1324,60 @@ late_initcall(of_fdt_raw_init); >>> #endif >>> >>> #endif /* CONFIG_OF_EARLY_FLATTREE */ >>> + >> >> Please add comment: >> >> /* helper functions for arm64 kexec */ >> >> >>> +bool of_fdt_cells_size_fitted(u64 base, u64 size) >> >> Please rename as of_fdt_range_valid() >> >> >>> +{ >>> + /* if *_cells >= 2, cells can hold 64-bit values anyway */ >>> + if ((dt_root_addr_cells == 1) && (base > U32_MAX)) >>> + return false; >>> + >>> + if ((dt_root_size_cells == 1) && (size > U32_MAX)) >>> + return false; >> >> Should also check that base + size does not wrap around. > > What is the upper limit here? > For instance, #address_cells = <1> and #size_cells = <1>, > and can 'base + size' be over U32_MAX? > Assuming 'not' is quite reasonable, but it seems to me > that devicetree spec doesn't exclude it, as least I couldn't > find any notes about such a case. > (In my understands, #address_cells only restricts a size in 'reg' property.) (See my other reply in this thread a few minutes ago -- the context of the ranges is essentially what is valid for the "reg" property of the "/memory" nodes.) The "Devicetree Specification" does not specify whether a memory range can wrap around. For example, can a region of size 0x2000 that wraps around the highest 32 bit address be specified as: / memory@0xfffff000 { reg = <0xfffff000 0x2000>; } or must it be specified as (option 1): / memory@0xfffff000 { reg = <0xfffff000 0x1000 0x0 0x1000> } or (option 2): / memory@0xfffff000 { reg = <0xfffff000 0x1000>; } memory@0 { reg = <0x0 0x1000>; } I suggest you start a thread on the devicetree specification list asking that the spec be updated to state whether wrap around is allowed. > > Thanks, > -Takahiro Akashi > >> >>> + >>> + return true; >>> +} >>> + >>> +size_t of_fdt_reg_cells_size(void) >> >> Please rename as of_fdt_root_range_size() >> >> >>> +{ >>> + return (dt_root_addr_cells + dt_root_size_cells) * sizeof(u32); >>> +} >>> + >>> +#define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1)) >>> +#define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE)) >>> + >>> +int fdt_prop_len(const char *prop_name, int len) >> >> Please rename as fdt_len_added_prop() >> >> >>> +{ >>> + return (strlen(prop_name) + 1) + >>> + sizeof(struct fdt_property) + >>> + FDT_TAGALIGN(len); >>> +} >>> + >> >> Please add comment, something like: >> >> /* cells must be 1 or 2 */ >> >> >>> +static void fill_property(void *buf, u64 val64, int cells) >> >> Please rename as cpu64_to_fdt_cells() >> >> Thanks, >> >> Frank >> >>> +{ >>> + __be32 val32; >>> + >>> + while (cells) { >>> + val32 = cpu_to_fdt32((val64 >> (32 * (--cells))) & U32_MAX); >>> + memcpy(buf, &val32, sizeof(val32)); >>> + buf += sizeof(val32); >>> + } >>> +} >>> + >>> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name, >>> + u64 addr, u64 size) >>> +{ >>> + char buf[sizeof(__be32) * 2 * 2]; >>> + /* assume dt_root_[addr|size]_cells <= 2 */ >>> + void *prop; >>> + size_t buf_size; >>> + >>> + buf_size = of_fdt_reg_cells_size(); >>> + prop = buf; >>> + >>> + fill_property(prop, addr, dt_root_addr_cells); >>> + prop += dt_root_addr_cells * sizeof(u32); >>> + >>> + fill_property(prop, size, dt_root_size_cells); >>> + >>> + return fdt_setprop(fdt, nodeoffset, name, buf, buf_size); >>> +} >>> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h >>> index b9cd9ebdf9b9..9615d6142578 100644 >>> --- a/include/linux/of_fdt.h >>> +++ b/include/linux/of_fdt.h >>> @@ -37,8 +37,8 @@ extern void *of_fdt_unflatten_tree(const unsigned long *blob, >>> struct device_node **mynodes); >>> >>> /* TBD: Temporary export of fdt globals - remove when code fully merged */ >>> -extern int __initdata dt_root_addr_cells; >>> -extern int __initdata dt_root_size_cells; >>> +extern int dt_root_addr_cells; >>> +extern int dt_root_size_cells; >>> extern void *initial_boot_params; >>> >>> extern char __dtb_start[]; >>> @@ -108,5 +108,11 @@ static inline void unflatten_device_tree(void) {} >>> static inline void unflatten_and_copy_device_tree(void) {} >>> #endif /* CONFIG_OF_EARLY_FLATTREE */ >>> >>> +bool of_fdt_cells_size_fitted(u64 base, u64 size); >>> +size_t of_fdt_reg_cells_size(void); >>> +int fdt_prop_len(const char *prop_name, int len); >>> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name, >>> + u64 addr, u64 size); >>> + >>> #endif /* __ASSEMBLY__ */ >>> #endif /* _LINUX_OF_FDT_H */ >>> >> >