From: Julien Thierry <jthierry@redhat.com>
To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: mark.rutland@arm.com, linux-efi@vger.kernel.org,
michal.lkml@markovi.net, keescook@chromium.org,
peterz@infradead.org, catalin.marinas@arm.com,
masahiroy@kernel.org, Raphael Gault <raphael.gault@arm.com>,
broonie@kernel.org, linux-hardening@vger.kernel.org,
jpoimboe@redhat.com, will@kernel.org, ardb@kernel.org,
Julien Thierry <jthierry@redhat.com>
Subject: [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64
Date: Wed, 20 Jan 2021 18:37:55 +0100 [thread overview]
Message-ID: <20210120173800.1660730-13-jthierry@redhat.com> (raw)
In-Reply-To: <20210120173800.1660730-1-jthierry@redhat.com>
From: Raphael Gault <raphael.gault@arm.com>
This plugins comes into play before the final 2 RTL passes of GCC and
detects switch-tables that are to be outputed in the ELF and writes
information in an ".discard.switch_table_info" section which will be
used by objtool.
Signed-off-by: Raphael Gault <raphael.gault@arm.com>
[J.T.: Change section name to store switch table information,
Make plugin Kconfig be selected rather than opt-in by user,
Add a relocation in the switch_table_info that points to
the jump operation itself]
Signed-off-by: Julien Thierry <jthierry@redhat.com>
---
arch/arm64/Kconfig | 1 +
scripts/Makefile.gcc-plugins | 2 +
scripts/gcc-plugins/Kconfig | 4 +
.../arm64_switch_table_detection_plugin.c | 85 +++++++++++++++++++
4 files changed, 92 insertions(+)
create mode 100644 scripts/gcc-plugins/arm64_switch_table_detection_plugin.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 05e17351e4f3..93a320cc8e03 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -100,6 +100,7 @@ config ARM64
select DMA_DIRECT_REMAP
select EDAC_SUPPORT
select FRAME_POINTER
+ select GCC_PLUGIN_SWITCH_TABLES if STACK_VALIDATION
select GENERIC_ALLOCATOR
select GENERIC_ARCH_TOPOLOGY
select GENERIC_CLOCKEVENTS_BROADCAST
diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
index 952e46876329..8af322311f6b 100644
--- a/scripts/Makefile.gcc-plugins
+++ b/scripts/Makefile.gcc-plugins
@@ -46,6 +46,8 @@ ifdef CONFIG_GCC_PLUGIN_ARM_SSP_PER_TASK
endif
export DISABLE_ARM_SSP_PER_TASK_PLUGIN
+gcc-plugin-$(CONFIG_GCC_PLUGIN_SWITCH_TABLES) += arm64_switch_table_detection_plugin.so
+
# All the plugin CFLAGS are collected here in case a build target needs to
# filter them out of the KBUILD_CFLAGS.
GCC_PLUGINS_CFLAGS := $(strip $(addprefix -fplugin=$(objtree)/scripts/gcc-plugins/, $(gcc-plugin-y)) $(gcc-plugin-cflags-y))
diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
index ab9eb4cbe33a..76efbb97d223 100644
--- a/scripts/gcc-plugins/Kconfig
+++ b/scripts/gcc-plugins/Kconfig
@@ -104,4 +104,8 @@ config GCC_PLUGIN_ARM_SSP_PER_TASK
bool
depends on GCC_PLUGINS && ARM
+config GCC_PLUGIN_SWITCH_TABLES
+ bool
+ depends on GCC_PLUGINS && ARM64
+
endif
diff --git a/scripts/gcc-plugins/arm64_switch_table_detection_plugin.c b/scripts/gcc-plugins/arm64_switch_table_detection_plugin.c
new file mode 100644
index 000000000000..60ef00ff2c5b
--- /dev/null
+++ b/scripts/gcc-plugins/arm64_switch_table_detection_plugin.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <stdio.h>
+#include "gcc-common.h"
+
+__visible int plugin_is_GPL_compatible;
+
+#define GEN_QUAD(rtx) assemble_integer_with_op(".quad ", rtx)
+
+/*
+ * Create an array of metadata for each jump table found in the rtl.
+ * The metadata contains:
+ * - A reference to first instruction part of the RTL expanded into an
+ * acutal jump
+ * - The number of entries in the table of offsets
+ * - A reference to each possible jump target
+ *
+ * Separate each entry with a null quad word.
+ */
+static unsigned int arm64_switchtbl_rtl_execute(void)
+{
+ rtx_insn *insn;
+ rtx_insn *labelp = NULL;
+ rtx_jump_table_data *tablep = NULL;
+ section *swt_sec;
+ section *curr_sec = current_function_section();
+
+ swt_sec = get_section(".discard.switch_table_info",
+ SECTION_DEBUG | SECTION_EXCLUDE, NULL);
+
+ for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) {
+ /*
+ * Find a tablejump_p INSN (using a dispatch table)
+ */
+ if (!tablejump_p(insn, &labelp, &tablep))
+ continue;
+
+ if (labelp && tablep) {
+ rtx_code_label *label_to_jump;
+ rtvec jump_labels = tablep->get_labels();
+ int nr_labels = GET_NUM_ELEM(jump_labels);
+ int i;
+
+ label_to_jump = gen_label_rtx();
+ SET_LABEL_KIND(label_to_jump, LABEL_NORMAL);
+ emit_label_before(label_to_jump, insn);
+ LABEL_PRESERVE_P(label_to_jump) = 1;
+
+ switch_to_section(swt_sec);
+ GEN_QUAD(GEN_INT(0)); // mark separation between rela tables
+ GEN_QUAD(gen_rtx_LABEL_REF(Pmode, label_to_jump));
+ GEN_QUAD(GEN_INT(nr_labels));
+ for (i = 0; i < nr_labels; i++)
+ GEN_QUAD(gen_rtx_LABEL_REF(Pmode,
+ label_ref_label(RTVEC_ELT(jump_labels, i))));
+ switch_to_section(curr_sec);
+ delete_insn(label_to_jump);
+ }
+ }
+ return 0;
+}
+
+#define PASS_NAME arm64_switchtbl_rtl
+
+#define NO_GATE
+#include "gcc-generate-rtl-pass.h"
+
+__visible int plugin_init(struct plugin_name_args *plugin_info,
+ struct plugin_gcc_version *version)
+{
+ const char * const plugin_name = plugin_info->base_name;
+
+ if (!plugin_default_version_check(version, &gcc_version)) {
+ error(G_("incompatible gcc/plugin versions"));
+ return 1;
+ }
+
+ PASS_INFO(arm64_switchtbl_rtl, "final", 1,
+ PASS_POS_INSERT_BEFORE);
+
+ register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP,
+ NULL, &arm64_switchtbl_rtl_pass_info);
+
+ return 0;
+}
--
2.25.4
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next prev parent reply other threads:[~2021-01-20 17:46 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 17:37 [RFC PATCH 00/17] objtool: add base support for arm64 Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 01/17] tools: Add some generic functions and headers Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 02/17] tools: arm64: Make aarch64 instruction decoder available to tools Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 03/17] tools: bug: Remove duplicate definition Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 04/17] objtool: arm64: Add base definition for arm64 backend Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 05/17] objtool: arm64: Decode add/sub instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 06/17] objtool: arm64: Decode jump and call related instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 07/17] objtool: arm64: Decode other system instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 08/17] objtool: arm64: Decode load/store instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 09/17] objtool: arm64: Decode LDR instructions Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 10/17] objtool: arm64: Accept padding in code sections Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 11/17] efi: libstub: Ignore relocations for .discard sections Julien Thierry
2021-01-20 17:37 ` Julien Thierry [this message]
2021-01-27 22:15 ` [RFC PATCH 12/17] gcc-plugins: objtool: Add plugin to detect switch table on arm64 Nick Desaulniers
2021-01-27 23:26 ` Josh Poimboeuf
2021-01-29 18:10 ` Nick Desaulniers
2021-02-01 21:44 ` Josh Poimboeuf
2021-02-01 23:17 ` Nick Desaulniers
2021-02-02 0:02 ` Josh Poimboeuf
2021-02-02 14:24 ` David Laight
2021-02-02 22:33 ` Nick Desaulniers
2021-02-02 23:36 ` Josh Poimboeuf
2021-02-02 23:52 ` Nick Desaulniers
2021-02-02 8:57 ` Julien Thierry
2021-02-02 23:01 ` Nick Desaulniers
2021-02-03 0:14 ` Josh Poimboeuf
2021-02-03 11:57 ` Peter Zijlstra
2021-02-03 13:04 ` Mark Brown
2021-02-03 13:58 ` Mark Rutland
2021-02-03 8:11 ` Julien Thierry
2021-02-09 16:30 ` Daniel Kiss
2021-01-20 17:37 ` [RFC PATCH 13/17] objtool: arm64: Implement functions to add switch tables alternatives Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 14/17] objtool: arm64: Cache section with switch table information Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 15/17] objtool: arm64: Handle supported relocations in alternatives Julien Thierry
2021-01-20 17:37 ` [RFC PATCH 16/17] objtool: arm64: Ignore replacement section for alternative callback Julien Thierry
2021-01-20 17:38 ` [RFC PATCH 17/17] objtool: arm64: Enable stack validation for arm64 Julien Thierry
2021-01-21 9:03 ` [RFC PATCH 00/17] objtool: add base support " Ard Biesheuvel
2021-01-21 10:26 ` Julien Thierry
2021-01-21 11:08 ` Ard Biesheuvel
2021-01-21 11:23 ` Peter Zijlstra
2021-01-21 11:48 ` Ard Biesheuvel
2021-01-21 18:54 ` Josh Poimboeuf
2021-01-22 17:43 ` Mark Brown
2021-01-22 17:54 ` Ard Biesheuvel
2021-01-28 22:10 ` Madhavan T. Venkataraman
2021-01-29 15:47 ` Mark Brown
2021-01-22 21:15 ` Madhavan T. Venkataraman
2021-01-22 21:43 ` Ard Biesheuvel
2021-01-22 21:44 ` Madhavan T. Venkataraman
2021-01-25 21:19 ` Josh Poimboeuf
2021-01-22 21:16 ` Madhavan T. Venkataraman
2021-01-21 13:23 ` Julien Thierry
2021-01-21 14:23 ` Mark Brown
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