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Mon, 26 Sep 2022 06:43:55 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AB32611C04C; Mon, 26 Sep 2022 06:43:54 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 26 Sep 2022 06:43:54 +0000 (GMT) Received: from beng-ozlabs-ibm-com.ozlabs.ibm.com (haven.au.ibm.com [9.192.254.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id C1BD26058C; Mon, 26 Sep 2022 16:43:45 +1000 (AEST) From: Benjamin Gray To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v2 2/6] powerpc/module: Handle caller-saved TOC in module linker Date: Mon, 26 Sep 2022 16:43:12 +1000 Message-Id: <20220926064316.765967-3-bgray@linux.ibm.com> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220926064316.765967-1-bgray@linux.ibm.com> References: <20220926064316.765967-1-bgray@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 1z5Vnnrv0KFoVkqbThVKXfnWBOZtOv02 X-Proofpoint-ORIG-GUID: GG3DUrlsywyd6RdpmkKnkVyL6vJdZYcY X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-26_04,2022-09-22_02,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 clxscore=1015 priorityscore=1501 phishscore=0 lowpriorityscore=0 mlxlogscore=999 bulkscore=0 adultscore=0 mlxscore=0 malwarescore=0 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2209130000 definitions=main-2209260039 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: christophe.leroy@c-s.fr, ajd@linux.ibm.com, peterz@infradead.org, Benjamin Gray , npiggin@gmail.com, ardb@kernel.org, jbaron@akamai.com, rostedt@goodmis.org, jpoimboe@kernel.org Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" The callee may set a field in `st_other` to 1 to indicate r2 should be treated as caller-saved. This means a trampoline must be used to save the current TOC before calling it and restore it afterwards, much like external calls. This is necessary for supporting V2 ABI static calls that do not preserve the TOC. Signed-off-by: Benjamin Gray --- arch/powerpc/kernel/module_64.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 7e45dc98df8a..4d816f7785b4 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -55,6 +55,12 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym) * of function and try to derive r2 from it). */ return PPC64_LOCAL_ENTRY_OFFSET(sym->st_other); } + +static bool need_r2save_stub(unsigned char st_other) +{ + return ((st_other & STO_PPC64_LOCAL_MASK) >> STO_PPC64_LOCAL_BIT) == 1; +} + #else static func_desc_t func_desc(unsigned long addr) @@ -66,6 +72,11 @@ static unsigned int local_entry_offset(const Elf64_Sym *sym) return 0; } +static bool need_r2save_stub(unsigned char st_other) +{ + return false; +} + void *dereference_module_function_descriptor(struct module *mod, void *ptr) { if (ptr < (void *)mod->arch.start_opd || @@ -632,7 +643,8 @@ int apply_relocate_add(Elf64_Shdr *sechdrs, case R_PPC_REL24: /* FIXME: Handle weak symbols here --RR */ if (sym->st_shndx == SHN_UNDEF || - sym->st_shndx == SHN_LIVEPATCH) { + sym->st_shndx == SHN_LIVEPATCH || + need_r2save_stub(sym->st_other)) { /* External: go via stub */ value = stub_for_addr(sechdrs, value, me, strtab + sym->st_name);