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([2804:431:c7ca:709a:aad4:4e8:bc05:17ad]) by smtp.gmail.com with ESMTPSA id 96sm6536971otv.33.2022.01.28.12.48.24 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 28 Jan 2022 12:48:25 -0800 (PST) Message-ID: <31decb16-c634-183a-a82d-6710157216af@linaro.org> Date: Fri, 28 Jan 2022 17:48:23 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.5.1 Subject: Re: [PATCH] mips: pldd: support DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL Content-Language: en-US To: libc-alpha@sourceware.org References: <046da3ae8fc57687b5a9480381904d3f53b1010f.camel@mengyan1223.wang> From: Adhemerval Zanella In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, NICE_REPLY_A, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 28 Jan 2022 20:48:29 -0000 On 28/01/2022 17:45, H.J. Lu via Libc-alpha wrote: > On Fri, Jan 28, 2022 at 10:57 AM Xi Ruoyao via Libc-alpha > wrote: >> >> MIPS uses DT_MIPS_RLD_MAP and DT_MIPS_RLD_MAP_REL for accessing r_debug, >> instead of DT_DEBUG. >> --- >> elf/pldd-xx.c | 67 ++++++++++++++++++++++++++++++++++++++++----------- >> 1 file changed, 53 insertions(+), 14 deletions(-) >> >> diff --git a/elf/pldd-xx.c b/elf/pldd-xx.c >> index 1cdfb49c53..ec397f00e5 100644 >> --- a/elf/pldd-xx.c >> +++ b/elf/pldd-xx.c >> @@ -22,6 +22,12 @@ >> #define EW_(e, w, t) EW__(e, w, _##t) >> #define EW__(e, w, t) e##w##t >> >> +#if CLASS == 32 >> +typedef Elf32_Word E(val_type); >> +#else >> +typedef Elf64_Xword E(val_type); >> +#endif >> + >> struct E(link_map) >> { >> EW(Addr) l_addr; >> @@ -70,6 +76,35 @@ _Static_assert (offsetof (struct r_debug, r_map) >> == offsetof (struct E(r_debug), r_map), "r_map"); >> #endif >> >> +static EW(Addr) >> +E(r_debug_offset) (EW(Dyn) *d, int memfd, EW(Addr) d_addr) >> +{ >> +#ifdef __mips__ >> + EW(Addr) ptr; >> + >> + switch (d->d_tag) >> + { >> + case DT_MIPS_RLD_MAP_REL: >> + ptr = d_addr + d->d_un.d_val; >> + break; >> + case DT_MIPS_RLD_MAP: >> + ptr = d->d_un.d_ptr; >> + break; >> + default: >> + return 0; >> + } >> + >> + if (pread (memfd, &ptr, sizeof (ptr), ptr) != sizeof (ptr)) >> + return 0; >> + >> + return ptr; >> +#else >> + if (d->d_tag == DT_DEBUG) >> + return (off_t) d->d_un.d_ptr; >> + >> + return 0; >> +#endif >> +} >> >> static int >> >> @@ -126,21 +161,25 @@ E(find_maps) (const char *exe, int memfd, pid_t pid, void *auxv, >> != p[i].p_filesz) >> error (EXIT_FAILURE, 0, gettext ("cannot read dynamic section")); >> >> - /* Search for the DT_DEBUG entry. */ >> + /* Search for the r_debug struct. */ >> for (unsigned int j = 0; j < p[i].p_filesz / sizeof (EW(Dyn)); ++j) >> - if (dyn[j].d_tag == DT_DEBUG && dyn[j].d_un.d_ptr != 0) >> - { >> - struct E(r_debug) r; >> - if (pread (memfd, &r, sizeof (r), dyn[j].d_un.d_ptr) >> - != sizeof (r)) >> - error (EXIT_FAILURE, 0, gettext ("cannot read r_debug")); >> - >> - if (r.r_map != 0) >> - { >> - list = r.r_map; >> - break; >> - } >> - } >> + { >> + EW(Addr) d_addr = offset + p[i].p_vaddr + sizeof (EW(Dyn)) * j; >> + EW(Addr) off = E(r_debug_offset)(&dyn[j], memfd, d_addr); >> + if (off != 0) >> + { >> + struct E(r_debug) r; >> + if (pread (memfd, &r, sizeof (r), off) >> + != sizeof (r)) >> + error (EXIT_FAILURE, 0, gettext ("cannot read r_debug")); >> + >> + if (r.r_map != 0) >> + { >> + list = r.r_map; >> + break; >> + } >> + } >> + } >> >> free (dyn); >> break; >> -- >> 2.35.0 >> >> > > I think a header file to access r_debug works better. MIPS can provide > one to override the generic header file. > Agreed, I think we should avoid arch specific defines (__mips__) on generic code.