Hi Ricardo and folks, On Fri, May 19, 2023 at 7:48 AM Ricardo Ribalda <riba...@chromium.org> wrote: > > 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. > > Signed-off-by: Ricardo Ribalda <riba...@chromium.org>
We are seeing WARNINGs like the following while kexec'ing a PGO and LTO enabled kernel: WARNING: CPU: 26 PID: 110894 at kernel/kexec_file.c:919 kexec_load_purgatory+0x37f/0x390 AFAICT, the warning was added by this set, and it was triggered when we have many .text sections in purgatory.ro. The kexec was actually successful. So I wonder whether we really need the WARNING here. If we disable LTO (PGO is still enabled), we don't see the WARNING any more. I also tested an older kernel (5.19 based), where we also see many .text sections with LTO. It kexec()'ed fine. (It doesn't have the WARN_ON() in kexec_purgatory_setup_sechdrs). Please help us fix this properly (as I really don't know much about kexec). Thanks in advance, Song Here is readelf -S output on purgatory.ro. With LTO: readelf -W -S purgatory.ro There are 48 section headers, starting at offset 0x4a10: Section Headers: [Nr] Name Type Address Off Size ES Flg Lk Inf Al [ 0] NULL 0000000000000000 000000 000000 00 0 0 0 [ 1] .text PROGBITS 0000000000000000 000040 0000d0 00 AX 0 0 16 [ 2] .data PROGBITS 0000000000000000 001000 001000 00 WA 0 0 4096 [ 3] .rela.text RELA 0000000000000000 003788 000228 18 I 45 1 8 [ 4] .rodata PROGBITS 0000000000000000 002000 0000e0 00 A 0 0 16 [ 5] .rela.rodata RELA 0000000000000000 0039b0 000030 18 I 45 4 8 [ 6] .bss NOBITS 0000000000000000 0020e0 001000 00 WA 0 0 4096 [ 7] .text.purgatory PROGBITS 0000000000000000 0020e0 0000df 00 AX 0 0 16 [ 8] .rela.text.purgatory RELA 0000000000000000 0039e0 000060 18 I 45 7 8 [ 9] .text.warn PROGBITS 0000000000000000 0021c0 000001 00 AX 0 0 16 [10] .kexec-purgatory PROGBITS 0000000000000000 0021d0 000120 00 WA 0 0 16 [11] .comment PROGBITS 0000000000000000 003a40 000046 01 MS 0 0 1 [12] .llvm_addrsig LOOS+0xfff4c03 0000000000000000 003a86 000005 00 E 0 0 1 [13] .text.sha256_update PROGBITS 0000000000000000 0022f0 0008eb 00 AX 0 0 16 [14] .rela.text.sha256_update RELA 0000000000000000 003a90 000060 18 I 45 13 8 [15] .text.sha224_update PROGBITS 0000000000000000 002be0 00000c 00 AX 0 0 16 [16] .rela.text.sha224_update RELA 0000000000000000 003af0 000018 18 I 45 15 8 [17] .text.sha256_final PROGBITS 0000000000000000 002bf0 0000cd 00 AX 0 0 16 [18] .rela.text.sha256_final RELA 0000000000000000 003b08 000030 18 I 45 17 8 [19] .text.sha224_final PROGBITS 0000000000000000 002cc0 0000bd 00 AX 0 0 16 [20] .rela.text.sha224_final RELA 0000000000000000 003b38 000030 18 I 45 19 8 [21] .text.sha256 PROGBITS 0000000000000000 002d80 00011d 00 AX 0 0 16 [22] .rela.text.sha256 RELA 0000000000000000 003b68 000030 18 I 45 21 8 [23] .modinfo PROGBITS 0000000000000000 002e9d 000039 00 A 0 0 1 [24] .rodata.SHA256_K PROGBITS 0000000000000000 002ee0 000100 00 A 0 0 16 [25] .rodata.__sha256_final.padding PROGBITS 0000000000000000 002fe0 000040 00 A 0 0 16 [26] .text.memcmp PROGBITS 0000000000000000 003020 00000b 00 AX 0 0 16 [27] .text.bcmp PROGBITS 0000000000000000 003030 00000b 00 AX 0 0 16 [28] .text.strcmp PROGBITS 0000000000000000 003040 000041 00 AX 0 0 16 [29] .text.strncmp PROGBITS 0000000000000000 003090 00003a 00 AX 0 0 16 [30] .text.strnlen PROGBITS 0000000000000000 0030d0 000039 00 AX 0 0 16 [31] .text.atou PROGBITS 0000000000000000 003110 000035 00 AX 0 0 16 [32] .text.simple_strtoull PROGBITS 0000000000000000 003150 0000b6 00 AX 0 0 16 [33] .text.simple_strtol PROGBITS 0000000000000000 003210 0001b6 00 AX 0 0 16 [34] .text.strlen PROGBITS 0000000000000000 0033d0 00001c 00 AX 0 0 16 [35] .text.strstr PROGBITS 0000000000000000 0033f0 00005f 00 AX 0 0 16 [36] .text.strchr PROGBITS 0000000000000000 003450 000022 00 AX 0 0 16 [37] .text.kstrtoull PROGBITS 0000000000000000 003480 000142 00 AX 0 0 16 [38] .text.boot_kstrtoul PROGBITS 0000000000000000 0035d0 00000c 00 AX 0 0 16 [39] .rela.text.boot_kstrtoul RELA 0000000000000000 003b98 000018 18 I 45 38 8 [40] .text.memset PROGBITS 0000000000000000 0035e0 00001f 00 AX 0 0 16 [41] .text.memmove PROGBITS 0000000000000000 003600 0000a6 00 AX 0 0 16 [42] .text.memcpy PROGBITS 0000000000000000 0036b0 0000a6 00 AX 0 0 16 [43] .rodata.str1.1 PROGBITS 0000000000000000 003756 000032 01 AMS 0 0 1 [44] .note.GNU-stack PROGBITS 0000000000000000 003bb0 000000 00 0 0 1 [45] .symtab SYMTAB 0000000000000000 003bb0 000948 18 47 68 8 [46] .shstrtab STRTAB 0000000000000000 0044f8 0002cd 00 0 0 1 [47] .strtab STRTAB 0000000000000000 0047c5 000248 00 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings), I (info), L (link order), O (extra OS processing required), G (group), T (TLS), C (compressed), x (unknown), o (OS specific), E (exclude), l (large), p (processor specific) Without LTO: readelf -W -S purgatory.ro There are 16 section headers, starting at offset 0x4130: Section Headers: [Nr] Name Type Address Off Size ES Flg Lk Inf Al [ 0] NULL 0000000000000000 000000 000000 00 0 0 0 [ 1] .text PROGBITS 0000000000000000 000040 00131b 00 AX 0 0 16 [ 2] .rela.text RELA 0000000000000000 003290 000480 18 I 13 1 8 [ 3] .kexec-purgatory PROGBITS 0000000000000000 001360 000120 00 WA 0 0 16 [ 4] .comment PROGBITS 0000000000000000 003710 000046 01 MS 0 0 1 [ 5] .llvm_addrsig LOOS+0xfff4c03 0000000000000000 003756 000005 00 E 0 0 1 [ 6] .data PROGBITS 0000000000000000 002000 001000 00 WA 0 0 4096 [ 7] .rodata PROGBITS 0000000000000000 003000 000220 00 A 0 0 16 [ 8] .rela.rodata RELA 0000000000000000 003760 000030 18 I 13 7 8 [ 9] .bss NOBITS 0000000000000000 003220 001000 00 WA 0 0 4096 [10] .modinfo PROGBITS 0000000000000000 003220 000039 00 A 0 0 1 [11] .rodata.str1.1 PROGBITS 0000000000000000 003259 000032 01 AMS 0 0 1 [12] .note.GNU-stack PROGBITS 0000000000000000 003790 000000 00 0 0 1 [13] .symtab SYMTAB 0000000000000000 003790 0006d8 18 15 43 8 [14] .shstrtab STRTAB 0000000000000000 003e68 00009c 00 0 0 1 [15] .strtab STRTAB 0000000000000000 003f04 00022b 00 0 0 1 Key to Flags: W (write), A (alloc), X (execute), M (merge), S (strings), I (info), L (link order), O (extra OS processing required), G (group), T (TLS), C (compressed), x (unknown), o (OS specific), E (exclude), l (large), p (processor specific) [...] > Ricardo Ribalda (4): > kexec: Support purgatories with .text.hot sections > x86/purgatory: Remove PGO flags > powerpc/purgatory: Remove PGO flags > riscv/purgatory: Remove PGO flags > > arch/powerpc/purgatory/Makefile | 5 +++++ > arch/riscv/purgatory/Makefile | 5 +++++ > arch/x86/purgatory/Makefile | 5 +++++ > kernel/kexec_file.c | 14 +++++++++++++- > 4 files changed, 28 insertions(+), 1 deletion(-) > --- > base-commit: 58390c8ce1bddb6c623f62e7ed36383e7fa5c02f > change-id: 20230321-kexec_clang16-4510c23d129c > > Best regards, > -- > Ricardo Ribalda Delgado <riba...@chromium.org> > _______________________________________________ kexec mailing list 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