From 013027918a4efa807409fcb356009c117e4d181a Mon Sep 17 00:00:00 2001 From: Ricardo Ribalda Date: Fri, 19 May 2023 16:47:36 +0200 Subject: [PATCH] kexec: support purgatories with .text.hot sections commit 8652d44f466ad5772e7d1756e9457046189b0dfc upstream. Patch series "kexec: Fix kexec_file_load for llvm16 with PGO", v7. When upreving llvm I realised that kexec stopped working on my test platform. The reason seems to be that due to PGO there are multiple .text sections on the purgatory, and kexec does not supports that. This patch (of 4): Clang16 links the purgatory text in two sections when PGO is in use: [ 1] .text PROGBITS 0000000000000000 00000040 00000000000011a1 0000000000000000 AX 0 0 16 [ 2] .rela.text RELA 0000000000000000 00003498 0000000000000648 0000000000000018 I 24 1 8 ... [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 immediately after: kexec_core: Starting new kernel Link: https://lkml.kernel.org/r/20230321-kexec_clang16-v7-0-b05c520b7296@chromium.org Link: https://lkml.kernel.org/r/20230321-kexec_clang16-v7-1-b05c520b7296@chromium.org Fixes: 930457057abe ("kernel/kexec_file.c: split up __kexec_load_puragory") Signed-off-by: Ricardo Ribalda Reviewed-by: Ross Zwisler Reviewed-by: Steven Rostedt (Google) Reviewed-by: Philipp Rudo Cc: Albert Ou Cc: Baoquan He Cc: Borislav Petkov (AMD) Cc: Christophe Leroy Cc: Dave Hansen Cc: Dave Young Cc: Eric W. Biederman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Michael Ellerman Cc: Nathan Chancellor Cc: Nicholas Piggin Cc: Nick Desaulniers Cc: Palmer Dabbelt Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Simon Horman Cc: Thomas Gleixner Cc: Tom Rix Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- kernel/kexec_file.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 4563751..6d787ae9 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -898,10 +898,22 @@ 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 section + * (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, and warn the user so they + * have a chance to fix their purgatory's linker script. + */ 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) && + !WARN_ON(kbuf->image->start != pi->ehdr->e_entry)) { kbuf->image->start -= sechdrs[i].sh_addr; kbuf->image->start += kbuf->mem + offset; } -- 2.7.4