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a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689254269; bh=XkuqR9+OmJB+cQyg5eR/C6W11JZP+75jrSQ8yU4aF/c=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=hgvZgsHr+Nxo1yQxxS4Q92P6ny42qWbiuhEfimWBRzRooVNvDpCAyvCyfa+Ko0HAH M2JVIp8UuG6AFvr9LGUhX3a1oEhQkHHsEHn/KKg/P7H+BrV1GOgwt12bIXFqU33Fs2 HELT8ZU+wG+v0LnvVrevjz7Fgpa5vsYkfemhckJDrINGHu9K+1ADXv1JUEohjLGUiv gTwljY270JEMYVRNtFBqJdhKSFR0l5Q755IQrobN4EkcMOY8Mhd9Bp5O6dy+b9O1gG 5Crm4cTJd6xs6CJCmxUO9wX4hyqIY7J3uzGYqA2X4P6Wpcuibx8JPWO4esySDHqFFX ppwt7eKZevq0w== Message-ID: <08905362-248c-e6af-d750-9d385ad543e3@kernel.org> Date: Thu, 13 Jul 2023 23:17:45 +1000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.11.0 Subject: Re: [PATCH v2 2/2] riscv: support the elf-fdpic binfmt loader Content-Language: en-US To: Stefan O'Rear , linux-riscv@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Palmer Dabbelt , viro@zeniv.linux.org.uk, ebiederm@xmission.com, keescook@chromium.org, brauner@kernel.org References: <20230711130754.481209-1-gerg@kernel.org> <20230711130754.481209-3-gerg@kernel.org> <31c4024b-3553-4117-a22a-b39259c8fea4@app.fastmail.com> From: Greg Ungerer In-Reply-To: <31c4024b-3553-4117-a22a-b39259c8fea4@app.fastmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 3E4EE140024 X-Stat-Signature: 8xksahc5e1xjc4dycn7p83shmakksrhr X-HE-Tag: 1689254271-157754 X-HE-Meta: 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 OYYXRvv+ okrcbDH2qvdW6hRniMeh6T/R+Kj+UbjURJ2VOJyIJpwB83GLN95qULeB5woyirlS7dRbX1SKL4V765IAxE0e9umgY7vGBGhNQc+n+r6gilt1KcMZ24oVUkpNbntiTvH8N8Pl5JdJ99poR3UWGDqmGg3pqE58cCkVBcjtqlGIFqLPxeIfqp30C5C4644gvp6nWQ2tSbUsu0F82AlOdDGxFIKcdFz2INBP/sIazKGQSmpWkBkB02lTTWU8rXqchj3SyFqFOl4GvTKIsEDpccWj93rbO97Ah2OylQ+d4D4jYM/3FuYp3kqvi3gIBrGfeH042iZp4 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 13/7/23 01:12, Stefan O'Rear wrote: > On Tue, Jul 11, 2023, at 9:07 AM, Greg Ungerer wrote: >> Add support for enabling and using the binfmt_elf_fdpic program loader >> on RISC-V platforms. The most important change is to setup registers >> during program load to pass the mapping addresses to the new process. >> >> One of the interesting features of the elf-fdpic loader is that it >> also allows appropriately compiled ELF format binaries to be loaded on >> nommu systems. Appropriate being those compiled with -pie. >> >> Signed-off-by: Greg Ungerer >> --- >> v1->v2: rebase onto linux-6.5-rc1 >> increment PTRACE_GETFDPIC value to keep it unique >> >> arch/riscv/include/asm/elf.h | 11 ++++++++++- >> arch/riscv/include/asm/mmu.h | 4 ++++ >> arch/riscv/include/uapi/asm/ptrace.h | 5 +++++ >> fs/Kconfig.binfmt | 2 +- >> 4 files changed, 20 insertions(+), 2 deletions(-) >> >> diff --git a/arch/riscv/include/asm/elf.h b/arch/riscv/include/asm/elf.h >> index c24280774caf..c33fe923ef6d 100644 >> --- a/arch/riscv/include/asm/elf.h >> +++ b/arch/riscv/include/asm/elf.h >> @@ -41,6 +41,7 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr); >> #define compat_elf_check_arch compat_elf_check_arch >> >> #define CORE_DUMP_USE_REGSET >> +#define ELF_FDPIC_CORE_EFLAGS 0 >> #define ELF_EXEC_PAGESIZE (PAGE_SIZE) >> >> /* >> @@ -69,6 +70,13 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr); >> #define ELF_HWCAP riscv_get_elf_hwcap() >> extern unsigned long elf_hwcap; >> >> +#define ELF_FDPIC_PLAT_INIT(_r, _exec_map_addr, _interp_map_addr, >> dynamic_addr) \ >> + do { \ >> + (_r)->a1 = _exec_map_addr; \ >> + (_r)->a2 = _interp_map_addr; \ >> + (_r)->a3 = dynamic_addr; \ >> + } while (0) >> + > > This should probably be left empty for now; it will be defined by the > ELF FDPIC ABI when that is done, and shouldn't be used by normal ELF > binaries. True, not used by the ELF binaries themselves. But used by an ELF interpreter to do the runtime relocations. > I'd ask if there's a reason it starts at a1 instead of a0, > but it seems idiosyncratic on all arches that have full FDPIC support. This comment in the crt1.S code of uClibc made me think that a0 already had a pre-defined use in the ABI: /* The entry point's job is to call __uClibc_main. Per the ABI, a0 contains the address of a function to be passed to atexit. But I didn't dig any further than that. Regards Greg > -s > >> /* >> * This yields a string that ld.so will use to load implementation >> * specific libraries for optimization. This is more specific in >> @@ -78,7 +86,6 @@ extern unsigned long elf_hwcap; >> >> #define COMPAT_ELF_PLATFORM (NULL) >> >> -#ifdef CONFIG_MMU >> #define ARCH_DLINFO \ >> do { \ >> /* \ >> @@ -115,6 +122,8 @@ do { \ >> else \ >> NEW_AUX_ENT(AT_IGNORE, 0); \ >> } while (0) >> + >> +#ifdef CONFIG_MMU >> #define ARCH_HAS_SETUP_ADDITIONAL_PAGES >> struct linux_binprm; >> extern int arch_setup_additional_pages(struct linux_binprm *bprm, >> diff --git a/arch/riscv/include/asm/mmu.h b/arch/riscv/include/asm/mmu.h >> index 0099dc116168..355504b37f8e 100644 >> --- a/arch/riscv/include/asm/mmu.h >> +++ b/arch/riscv/include/asm/mmu.h >> @@ -20,6 +20,10 @@ typedef struct { >> /* A local icache flush is needed before user execution can resume. */ >> cpumask_t icache_stale_mask; >> #endif >> +#ifdef CONFIG_BINFMT_ELF_FDPIC >> + unsigned long exec_fdpic_loadmap; >> + unsigned long interp_fdpic_loadmap; >> +#endif >> } mm_context_t; >> >> void __init create_pgd_mapping(pgd_t *pgdp, uintptr_t va, phys_addr_t >> pa, >> diff --git a/arch/riscv/include/uapi/asm/ptrace.h >> b/arch/riscv/include/uapi/asm/ptrace.h >> index e17c550986a6..30f6d6537adc 100644 >> --- a/arch/riscv/include/uapi/asm/ptrace.h >> +++ b/arch/riscv/include/uapi/asm/ptrace.h >> @@ -10,6 +10,11 @@ >> >> #include >> >> +#define PTRACE_GETFDPIC 33 >> + >> +#define PTRACE_GETFDPIC_EXEC 0 >> +#define PTRACE_GETFDPIC_INTERP 1 >> + >> /* >> * User-mode register state for core dumps, ptrace, sigcontext >> * >> diff --git a/fs/Kconfig.binfmt b/fs/Kconfig.binfmt >> index 93539aac0e5b..f5693164ca9a 100644 >> --- a/fs/Kconfig.binfmt >> +++ b/fs/Kconfig.binfmt >> @@ -58,7 +58,7 @@ config ARCH_USE_GNU_PROPERTY >> config BINFMT_ELF_FDPIC >> bool "Kernel support for FDPIC ELF binaries" >> default y if !BINFMT_ELF >> - depends on ARM || ((M68K || SUPERH || XTENSA) && !MMU) >> + depends on ARM || ((M68K || RISCV || SUPERH || XTENSA) && !MMU) >> select ELFCORE >> help >> ELF FDPIC binaries are based on ELF, but allow the individual load >> -- >> 2.25.1 >> >> >> _______________________________________________ >> linux-riscv mailing list >> linux-riscv@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-riscv