From: Ard Biesheuvel <ardb+git@google.com>
To: linux-kernel@vger.kernel.org
Cc: llvm@lists.linux.dev, keescook@chromium.org,
linux-hardening@vger.kernel.org, nathan@kernel.org,
Ard Biesheuvel <ardb@kernel.org>,
Josh Poimboeuf <jpoimboe@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Jan Beulich <jbeulich@suse.com>,
"Jose E. Marchesi" <jemarch@gnu.org>,
Kees Cook <kees@kernel.org>
Subject: [PATCH v3 2/8] objtool: Allow arch code to discover jump table size
Date: Fri, 11 Oct 2024 19:08:50 +0200 [thread overview]
Message-ID: <20241011170847.334429-12-ardb+git@google.com> (raw)
In-Reply-To: <20241011170847.334429-10-ardb+git@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
In preparation for adding support for annotated jump tables, where
ELF relocations and symbols are used to describe the locations of jump
tables in the executable, refactor the jump table discovery logic so the
table size can be returned from arch_find_switch_table().
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
tools/objtool/arch/loongarch/special.c | 3 +-
tools/objtool/arch/powerpc/special.c | 3 +-
tools/objtool/arch/x86/special.c | 4 ++-
tools/objtool/check.c | 31 +++++++++++++-------
tools/objtool/include/objtool/check.h | 5 +++-
tools/objtool/include/objtool/special.h | 3 +-
6 files changed, 33 insertions(+), 16 deletions(-)
diff --git a/tools/objtool/arch/loongarch/special.c b/tools/objtool/arch/loongarch/special.c
index 9bba1e9318e0..87230ed570fd 100644
--- a/tools/objtool/arch/loongarch/special.c
+++ b/tools/objtool/arch/loongarch/special.c
@@ -9,7 +9,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
}
struct reloc *arch_find_switch_table(struct objtool_file *file,
- struct instruction *insn)
+ struct instruction *insn,
+ unsigned long *table_size)
{
return NULL;
}
diff --git a/tools/objtool/arch/powerpc/special.c b/tools/objtool/arch/powerpc/special.c
index d33868147196..51610689abf7 100644
--- a/tools/objtool/arch/powerpc/special.c
+++ b/tools/objtool/arch/powerpc/special.c
@@ -13,7 +13,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
}
struct reloc *arch_find_switch_table(struct objtool_file *file,
- struct instruction *insn)
+ struct instruction *insn,
+ unsigned long *table_size)
{
exit(-1);
}
diff --git a/tools/objtool/arch/x86/special.c b/tools/objtool/arch/x86/special.c
index 415e4d035e53..f8fb67636384 100644
--- a/tools/objtool/arch/x86/special.c
+++ b/tools/objtool/arch/x86/special.c
@@ -109,7 +109,8 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
* NOTE: MITIGATION_RETPOLINE made it harder still to decode dynamic jumps.
*/
struct reloc *arch_find_switch_table(struct objtool_file *file,
- struct instruction *insn)
+ struct instruction *insn,
+ unsigned long *table_size)
{
struct reloc *text_reloc, *rodata_reloc;
struct section *table_sec;
@@ -150,5 +151,6 @@ struct reloc *arch_find_switch_table(struct objtool_file *file,
if (!rodata_reloc)
return NULL;
+ *table_size = 0;
return rodata_reloc;
}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index aa07fdf1cf13..b73e43b9b9e3 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -150,6 +150,15 @@ static inline struct reloc *insn_jump_table(struct instruction *insn)
return NULL;
}
+static inline unsigned long insn_jump_table_size(struct instruction *insn)
+{
+ if (insn->type == INSN_JUMP_DYNAMIC ||
+ insn->type == INSN_CALL_DYNAMIC)
+ return insn->_jump_table_size;
+
+ return 0;
+}
+
static bool is_jump_table_jump(struct instruction *insn)
{
struct alt_group *alt_group = insn->alt_group;
@@ -2099,6 +2108,7 @@ static int add_special_section_alts(struct objtool_file *file)
static int add_jump_table(struct objtool_file *file, struct instruction *insn,
struct reloc *next_table)
{
+ unsigned long table_size = insn_jump_table_size(insn);
struct symbol *pfunc = insn_func(insn)->pfunc;
struct reloc *table = insn_jump_table(insn);
unsigned int rtype = reloc_type(table);
@@ -2116,6 +2126,8 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
unsigned long addend = reloc_addend(reloc);
/* Check for the end of the table: */
+ if (table_size && reloc_offset(reloc) - reloc_offset(table) >= table_size)
+ break;
if (reloc != table && reloc == next_table)
break;
@@ -2175,12 +2187,12 @@ static int add_jump_table(struct objtool_file *file, struct instruction *insn,
* find_jump_table() - Given a dynamic jump, find the switch jump table
* associated with it.
*/
-static struct reloc *find_jump_table(struct objtool_file *file,
- struct symbol *func,
- struct instruction *insn)
+static void find_jump_table(struct objtool_file *file, struct symbol *func,
+ struct instruction *insn)
{
struct reloc *table_reloc;
struct instruction *dest_insn, *orig_insn = insn;
+ unsigned long table_size;
/*
* Backward search using the @first_jump_src links, these help avoid
@@ -2201,17 +2213,17 @@ static struct reloc *find_jump_table(struct objtool_file *file,
insn->jump_dest->offset > orig_insn->offset))
break;
- table_reloc = arch_find_switch_table(file, insn);
+ table_reloc = arch_find_switch_table(file, insn, &table_size);
if (!table_reloc)
continue;
dest_insn = find_insn(file, table_reloc->sym->sec, reloc_addend(table_reloc));
if (!dest_insn || !insn_func(dest_insn) || insn_func(dest_insn)->pfunc != func)
continue;
- return table_reloc;
+ orig_insn->_jump_table = table_reloc;
+ orig_insn->_jump_table_size = table_size;
+ break;
}
-
- return NULL;
}
/*
@@ -2222,7 +2234,6 @@ static void mark_func_jump_tables(struct objtool_file *file,
struct symbol *func)
{
struct instruction *insn, *last = NULL;
- struct reloc *reloc;
func_for_each_insn(file, func, insn) {
if (!last)
@@ -2245,9 +2256,7 @@ static void mark_func_jump_tables(struct objtool_file *file,
if (insn->type != INSN_JUMP_DYNAMIC)
continue;
- reloc = find_jump_table(file, func, insn);
- if (reloc)
- insn->_jump_table = reloc;
+ find_jump_table(file, func, insn);
}
}
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index daa46f1f0965..e1cd13cd28a3 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -71,7 +71,10 @@ struct instruction {
struct instruction *first_jump_src;
union {
struct symbol *_call_dest;
- struct reloc *_jump_table;
+ struct {
+ struct reloc *_jump_table;
+ unsigned long _jump_table_size;
+ };
};
struct alternative *alts;
struct symbol *sym;
diff --git a/tools/objtool/include/objtool/special.h b/tools/objtool/include/objtool/special.h
index 86d4af9c5aa9..e7ee7ffccefd 100644
--- a/tools/objtool/include/objtool/special.h
+++ b/tools/objtool/include/objtool/special.h
@@ -38,5 +38,6 @@ bool arch_support_alt_relocation(struct special_alt *special_alt,
struct instruction *insn,
struct reloc *reloc);
struct reloc *arch_find_switch_table(struct objtool_file *file,
- struct instruction *insn);
+ struct instruction *insn,
+ unsigned long *table_size);
#endif /* _SPECIAL_H */
--
2.47.0.rc1.288.g06298d1525-goog
next prev parent reply other threads:[~2024-10-11 17:09 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-11 17:08 [PATCH v3 0/8] Improve objtool jump table handling Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 1/8] objtool: Deal with relative jump tables correctly Ard Biesheuvel
2024-10-11 17:08 ` Ard Biesheuvel [this message]
2024-12-03 10:45 ` [tip: objtool/core] objtool: Allow arch code to discover jump table size tip-bot2 for Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 3/8] objtool: Make some helper functions globally accessible Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 4/8] objtool: Move jump table heuristics to a x86 specific source file Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 5/8] objtool: Add generic support for jump table annotations Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 6/8] crypto: x86/crc32c - Use idiomatic relative jump table Ard Biesheuvel
2024-10-14 4:28 ` Eric Biggers
2024-10-14 9:36 ` Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 7/8] crypto: x86/crc32c - Add jump table annotation Ard Biesheuvel
2024-10-11 17:08 ` [PATCH v3 8/8] crypto: x86/crc32c-intel - Tweaks to make objtool's life harder Ard Biesheuvel
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20241011170847.334429-12-ardb+git@google.com \
--to=ardb+git@google.com \
--cc=ardb@kernel.org \
--cc=jbeulich@suse.com \
--cc=jemarch@gnu.org \
--cc=jpoimboe@kernel.org \
--cc=kees@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=llvm@lists.linux.dev \
--cc=nathan@kernel.org \
--cc=peterz@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox