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-rw-r--r--debian/patches/bugfix/x86/retbleed/0007-x86-objtool-Create-.return_sites.patch202
1 files changed, 202 insertions, 0 deletions
diff --git a/debian/patches/bugfix/x86/retbleed/0007-x86-objtool-Create-.return_sites.patch b/debian/patches/bugfix/x86/retbleed/0007-x86-objtool-Create-.return_sites.patch
new file mode 100644
index 000000000..7014a0786
--- /dev/null
+++ b/debian/patches/bugfix/x86/retbleed/0007-x86-objtool-Create-.return_sites.patch
@@ -0,0 +1,202 @@
+From: Peter Zijlstra <peterz@infradead.org>
+Date: Tue, 14 Jun 2022 23:15:38 +0200
+Subject: x86,objtool: Create .return_sites
+Origin: https://git.kernel.org/linus/d9e9d2300681d68a775c28de6aa6e5290ae17796
+
+Find all the return-thunk sites and record them in a .return_sites
+section such that the kernel can undo this.
+
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Signed-off-by: Borislav Petkov <bp@suse.de>
+Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
+Signed-off-by: Borislav Petkov <bp@suse.de>
+---
+ tools/objtool/arch/x86/decode.c | 5 ++
+ tools/objtool/check.c | 74 +++++++++++++++++++++++++
+ tools/objtool/include/objtool/arch.h | 1 +
+ tools/objtool/include/objtool/elf.h | 1 +
+ tools/objtool/include/objtool/objtool.h | 1 +
+ tools/objtool/objtool.c | 1 +
+ 6 files changed, 83 insertions(+)
+
+diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c
+index 8b990a52aada..c260006106be 100644
+--- a/tools/objtool/arch/x86/decode.c
++++ b/tools/objtool/arch/x86/decode.c
+@@ -787,3 +787,8 @@ bool arch_is_retpoline(struct symbol *sym)
+ {
+ return !strncmp(sym->name, "__x86_indirect_", 15);
+ }
++
++bool arch_is_rethunk(struct symbol *sym)
++{
++ return !strcmp(sym->name, "__x86_return_thunk");
++}
+diff --git a/tools/objtool/check.c b/tools/objtool/check.c
+index 864bb9dd3584..f6d4ffa82432 100644
+--- a/tools/objtool/check.c
++++ b/tools/objtool/check.c
+@@ -749,6 +749,52 @@ static int create_retpoline_sites_sections(struct objtool_file *file)
+ return 0;
+ }
+
++static int create_return_sites_sections(struct objtool_file *file)
++{
++ struct instruction *insn;
++ struct section *sec;
++ int idx;
++
++ sec = find_section_by_name(file->elf, ".return_sites");
++ if (sec) {
++ WARN("file already has .return_sites, skipping");
++ return 0;
++ }
++
++ idx = 0;
++ list_for_each_entry(insn, &file->return_thunk_list, call_node)
++ idx++;
++
++ if (!idx)
++ return 0;
++
++ sec = elf_create_section(file->elf, ".return_sites", 0,
++ sizeof(int), idx);
++ if (!sec) {
++ WARN("elf_create_section: .return_sites");
++ return -1;
++ }
++
++ idx = 0;
++ list_for_each_entry(insn, &file->return_thunk_list, call_node) {
++
++ int *site = (int *)sec->data->d_buf + idx;
++ *site = 0;
++
++ if (elf_add_reloc_to_insn(file->elf, sec,
++ idx * sizeof(int),
++ R_X86_64_PC32,
++ insn->sec, insn->offset)) {
++ WARN("elf_add_reloc_to_insn: .return_sites");
++ return -1;
++ }
++
++ idx++;
++ }
++
++ return 0;
++}
++
+ static int create_ibt_endbr_seal_sections(struct objtool_file *file)
+ {
+ struct instruction *insn;
+@@ -1083,6 +1129,11 @@ __weak bool arch_is_retpoline(struct symbol *sym)
+ return false;
+ }
+
++__weak bool arch_is_rethunk(struct symbol *sym)
++{
++ return false;
++}
++
+ #define NEGATIVE_RELOC ((void *)-1L)
+
+ static struct reloc *insn_reloc(struct objtool_file *file, struct instruction *insn)
+@@ -1250,6 +1301,18 @@ static void add_retpoline_call(struct objtool_file *file, struct instruction *in
+ annotate_call_site(file, insn, false);
+ }
+
++static void add_return_call(struct objtool_file *file, struct instruction *insn)
++{
++ /*
++ * Return thunk tail calls are really just returns in disguise,
++ * so convert them accordingly.
++ */
++ insn->type = INSN_RETURN;
++ insn->retpoline_safe = true;
++
++ list_add_tail(&insn->call_node, &file->return_thunk_list);
++}
++
+ static bool same_function(struct instruction *insn1, struct instruction *insn2)
+ {
+ return insn1->func->pfunc == insn2->func->pfunc;
+@@ -1302,6 +1365,9 @@ static int add_jump_destinations(struct objtool_file *file)
+ } else if (reloc->sym->retpoline_thunk) {
+ add_retpoline_call(file, insn);
+ continue;
++ } else if (reloc->sym->return_thunk) {
++ add_return_call(file, insn);
++ continue;
+ } else if (insn->func) {
+ /*
+ * External sibling call or internal sibling call with
+@@ -2184,6 +2250,9 @@ static int classify_symbols(struct objtool_file *file)
+ if (arch_is_retpoline(func))
+ func->retpoline_thunk = true;
+
++ if (arch_is_rethunk(func))
++ func->return_thunk = true;
++
+ if (!strcmp(func->name, "__fentry__"))
+ func->fentry = true;
+
+@@ -3972,6 +4041,11 @@ int check(struct objtool_file *file)
+ if (ret < 0)
+ goto out;
+ warnings += ret;
++
++ ret = create_return_sites_sections(file);
++ if (ret < 0)
++ goto out;
++ warnings += ret;
+ }
+
+ if (opts.mcount) {
+diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
+index 9b19cc304195..beb2f3aa94ff 100644
+--- a/tools/objtool/include/objtool/arch.h
++++ b/tools/objtool/include/objtool/arch.h
+@@ -89,6 +89,7 @@ const char *arch_ret_insn(int len);
+ int arch_decode_hint_reg(u8 sp_reg, int *base);
+
+ bool arch_is_retpoline(struct symbol *sym);
++bool arch_is_rethunk(struct symbol *sym);
+
+ int arch_rewrite_retpolines(struct objtool_file *file);
+
+diff --git a/tools/objtool/include/objtool/elf.h b/tools/objtool/include/objtool/elf.h
+index adebfbc2b518..16f4067b82ae 100644
+--- a/tools/objtool/include/objtool/elf.h
++++ b/tools/objtool/include/objtool/elf.h
+@@ -57,6 +57,7 @@ struct symbol {
+ u8 uaccess_safe : 1;
+ u8 static_call_tramp : 1;
+ u8 retpoline_thunk : 1;
++ u8 return_thunk : 1;
+ u8 fentry : 1;
+ u8 profiling_func : 1;
+ struct list_head pv_target;
+diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
+index a6e72d916807..7f2d1b095333 100644
+--- a/tools/objtool/include/objtool/objtool.h
++++ b/tools/objtool/include/objtool/objtool.h
+@@ -24,6 +24,7 @@ struct objtool_file {
+ struct list_head insn_list;
+ DECLARE_HASHTABLE(insn_hash, 20);
+ struct list_head retpoline_call_list;
++ struct list_head return_thunk_list;
+ struct list_head static_call_list;
+ struct list_head mcount_loc_list;
+ struct list_head endbr_list;
+diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
+index 512669ce064c..a7ecc32e3512 100644
+--- a/tools/objtool/objtool.c
++++ b/tools/objtool/objtool.c
+@@ -102,6 +102,7 @@ struct objtool_file *objtool_open_read(const char *_objname)
+ INIT_LIST_HEAD(&file.insn_list);
+ hash_init(file.insn_hash);
+ INIT_LIST_HEAD(&file.retpoline_call_list);
++ INIT_LIST_HEAD(&file.return_thunk_list);
+ INIT_LIST_HEAD(&file.static_call_list);
+ INIT_LIST_HEAD(&file.mcount_loc_list);
+ INIT_LIST_HEAD(&file.endbr_list);
generated by cgit v1.2.3 (git 2.39.1) at 2024-08-09 02:28:20 +0000