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Thu, 3 Dec 2015 18:12:31 +0530 Received: from vineetg-E7440.internal.synopsys.com (10.12.197.182) by IN01WEHTCA.internal.synopsys.com (10.144.199.243) with Microsoft SMTP Server (TLS) id 14.3.195.1; Thu, 3 Dec 2015 18:12:31 +0530 From: Vineet Gupta To: Subject: [PATCH 12/17] ARC: dw2 unwind: Elide a loop if DW_CFA_register not present Date: Thu, 3 Dec 2015 18:11:10 +0530 Message-ID: <1449146475-15335-13-git-send-email-vgupta@synopsys.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1449146475-15335-1-git-send-email-vgupta@synopsys.com> References: <1449146475-15335-1-git-send-email-vgupta@synopsys.com> MIME-Version: 1.0 X-Originating-IP: [10.12.197.182] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20151203_044254_362482_2C08B97F X-CRM114-Status: GOOD ( 11.85 ) X-Spam-Score: -2.6 (--) X-Spam-Report: SpamAssassin version 3.4.0 on bombadil.infradead.org summary: Content analysis details: (-2.6 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_MSPIKE_H3 RBL: Good reputation (+3) [198.182.60.111 listed in wl.mailspike.net] -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at http://www.dnswl.org/, low trust [198.182.60.111 listed in list.dnswl.org] -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] -0.0 RCVD_IN_MSPIKE_WL Mailspike good senders X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Vineet Gupta , Alexey.Brodkin@synopsys.com, linux-kernel@vger.kernel.org, JBeulich@suse.com Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+incoming=patchwork.ozlabs.org@lists.infradead.org Signed-off-by: Vineet Gupta --- arch/arc/kernel/unwind.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-) diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c index b1a520afcbcb..6eb377c102c6 100644 --- a/arch/arc/kernel/unwind.c +++ b/arch/arc/kernel/unwind.c @@ -149,7 +149,7 @@ struct unwind_state { uleb128_t reg, offs; } cfa; struct unwind_item regs[ARRAY_SIZE(reg_info)]; - unsigned stackDepth; + unsigned stackDepth:8, has_cfa_register:8; const u8 *label; const u8 *stack[MAX_STACK_DEPTH]; }; @@ -697,6 +697,7 @@ static int processCFI(const u8 *start, const u8 *end, unsigned long targetLoc, case DW_CFA_register: str = "cfa_register: "; value = get_uleb128(&ptr.p8, end); + state->has_cfa_register = 1; set_rule(value, Register, get_uleb128(&ptr.p8, end), state, str); break; case DW_CFA_remember_state: @@ -1010,11 +1011,18 @@ int arc_unwind(struct unwind_frame_info *frame) unw_debug("\nCFA reg: r%ld, off: %ld => [SP] 0x%lx\n", state.cfa.reg, state.cfa.offs, cfa); - for (i = 0; i < ARRAY_SIZE(state.regs); ++i) { - switch (state.regs[i].where) { - default: - break; - case Register: + /* + * For DW_CFA_register instruction, save registers initial state + * Note that a seperate pass is needed (vs. doing this in main loop below) + * to capture state of those regs at time of entry into function since + * the main loop below can possibly clobber them due to CFA ops of + * function being processed + * + * Since ARC gcc doesn't seem to generate those (ABI thing ?) try to + * optimize out the loop + */ + for (i = 0; state.has_cfa_register && i < ARRAY_SIZE(state.regs); ++i) { + if (state.regs[i].where == Register) { if (state.regs[i].value >= ARRAY_SIZE(reg_info)) return -EIO; switch (reg_info[state.regs[i].value].width) { @@ -1039,7 +1047,6 @@ int arc_unwind(struct unwind_frame_info *frame) default: return -EIO; } - break; } }