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[81.140.166.164]) by smtp.gmail.com with ESMTPSA id e18sm8643101wrr.95.2020.01.09.08.06.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jan 2020 08:06:20 -0800 (PST) From: Julien Thierry To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: jpoimboe@redhat.com, peterz@infradead.org, raphael.gault@arm.com, catalin.marinas@arm.com, will@kernel.org, Julien Thierry Subject: [RFC v5 26/57] objtool: arm64: Decode brk instruction Date: Thu, 9 Jan 2020 16:02:29 +0000 Message-Id: <20200109160300.26150-27-jthierry@redhat.com> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200109160300.26150-1-jthierry@redhat.com> References: <20200109160300.26150-1-jthierry@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add decoding brk instructions. Associate known immediate values with their kernel/compiler semantics. Suggested-by: Raphael Gault Signed-off-by: Julien Thierry --- tools/objtool/arch/arm64/decode.c | 33 +++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/tools/objtool/arch/arm64/decode.c b/tools/objtool/arch/arm64/decode.c index aa00de725686..1609750cc4b9 100644 --- a/tools/objtool/arch/arm64/decode.c +++ b/tools/objtool/arch/arm64/decode.c @@ -507,6 +507,7 @@ int arm_decode_except_gen(u32 instr, enum insn_type *type, #define INSN_SVC 0b00000001 #define INSN_HVC 0b00000010 #define INSN_SMC 0b00000011 +#define INSN_BRK 0b00100000 switch (decode_field) { case INSN_SVC: @@ -518,6 +519,38 @@ int arm_decode_except_gen(u32 instr, enum insn_type *type, */ *type = INSN_NOP; return 0; + case INSN_BRK: + /* Based on arch/arm64/include/asm/brk-imm.h */ + switch (imm16) { + case 0x004: /* KPROBES_BRK_IMM */ + case 0x005: /* UPROBES_BRK_IMM */ + case 0x400: /* KGDB_DYN_DBG_BRK_IMM */ + case 0x401: /* KGDB_COMPILED_DBG_BRK_IMM */ + *type = INSN_OTHER; + break; + case 0x800: /* BUG_BRK_IMM */ + /* + * brk #0x800 is generated by the BUG()/WARN() linux API + * and is thus a particular case. Since those are not + * necessarily compiled in, the surrounding code should + * work properly without it. We thus consider it as a + * nop. + */ + *type = INSN_NOP; + break; + case 0x3e8: + /* + * Similar to the use of "ud2" on x86, GCC inserts + * "brk #0x38e" instructions for certain divide-by-zero + * cases. + */ + *type = INSN_BUG; + break; + default: + *type = INSN_CONTEXT_SWITCH; + break; + } + return 0; default: return arm_decode_unknown(instr, type, immediate, ops_list); } -- 2.21.0