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Mon, 27 Mar 2023 08:07:07 -0700 (PDT) Received: from alco.roam.corp.google.com ([2620:0:1059:10:ed3c:5e9e:b8e4:8695]) by smtp.gmail.com with ESMTPSA id t9-20020a50c249000000b005021d1ae6adsm5312428edf.28.2023.03.27.08.07.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Mar 2023 08:07:07 -0700 (PDT) From: Ricardo Ribalda Date: Mon, 27 Mar 2023 17:06:53 +0200 Subject: [PATCH v4 1/2] kexec: Support purgatories with .text.hot sections MIME-Version: 1.0 Message-Id: <20230321-kexec_clang16-v4-1-1340518f98e9@chromium.org> References: <20230321-kexec_clang16-v4-0-1340518f98e9@chromium.org> In-Reply-To: <20230321-kexec_clang16-v4-0-1340518f98e9@chromium.org> To: Eric Biederman Cc: linux-kernel@vger.kernel.org, Baoquan He , stable@vger.kernel.org, Ross Zwisler , Ricardo Ribalda , Philipp Rudo , Steven Rostedt , kexec@lists.infradead.org X-Mailer: b4 0.11.0-dev-696ae X-Developer-Signature: v=1; a=openpgp-sha256; l=2330; i=ribalda@chromium.org; h=from:subject:message-id; bh=Ei7yD2n0waFqw7CoS4vSLL1z8Jz5Bb9trLKry0qiinI=; 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[17] .text.hot. PROGBITS 0000000000000000 00003220 000000000000020b 0000000000000000 AX 0 0 1 [18] .rela.text.hot. RELA 0000000000000000 00004428 0000000000000078 0000000000000018 I 24 17 8 And both of them have their range [sh_addr ... sh_addr+sh_size] on the area pointed by `e_entry`. This causes that image->start is calculated twice, once for .text and another time for .text.hot. The second calculation leaves image->start in a random location. Because of this, the system crashes inmediatly after: kexec_core: Starting new kernel Cc: stable@vger.kernel.org Reviewed-by: Ross Zwisler Signed-off-by: Ricardo Ribalda --- kernel/kexec_file.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index f1a0e4e3fb5c..25a37d8f113a 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -901,10 +901,21 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi, } offset = ALIGN(offset, align); + + /* + * Check if the segment contains the entry point, if so, + * calculate the value of image->start based on it. + * If the compiler has produced more than one .text sections + * (Eg: .text.hot), they are generally after the main .text + * section, and they shall not be used to calculate + * image->start. So do not re-calculate image->start if it + * is not set to the initial value. + */ if (sechdrs[i].sh_flags & SHF_EXECINSTR && pi->ehdr->e_entry >= sechdrs[i].sh_addr && pi->ehdr->e_entry < (sechdrs[i].sh_addr - + sechdrs[i].sh_size)) { + + sechdrs[i].sh_size) && + kbuf->image->start == pi->ehdr->e_entry) { kbuf->image->start -= sechdrs[i].sh_addr; kbuf->image->start += kbuf->mem + offset; }