From d68133b5a81bd9c4b673c2a731ac1a33a9dc0cb8 Mon Sep 17 00:00:00 2001 From: Rabin Vincent <rabin@rab.in> Date: Tue, 24 Jan 2012 16:52:52 +0100 Subject: [PATCH] ARM: 7299/1: ftrace: clear zero bit in reported IPs for Thumb-2 The dynamic ftrace ops startup test currently fails on Thumb-2 kernels: Testing tracer function: PASSED Testing dynamic ftrace: PASSED Testing dynamic ftrace ops #1: (0 0 0 0 0) FAILED! This is because while the addresses in the mcount records do not have the zero bit set, the IP reported by the mcount call does have it set (because it is copied from the LR). This mismatch causes the ops filtering in ftrace_ops_list_func() to not call the relevant tracers. Fix this by clearing the zero bit before adjusting the LR for the mcount instruction size. Also, combine the mov+sub into a single sub instruction. Acked-by: Dave Martin <dave.martin@linaro.org> Signed-off-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> --- arch/arm/kernel/entry-common.S | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index 520889cf1b5b..9fd0ba90c1d2 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -149,6 +149,11 @@ ENDPROC(ret_from_fork) #endif #endif +.macro mcount_adjust_addr rd, rn + bic \rd, \rn, #1 @ clear the Thumb bit if present + sub \rd, \rd, #MCOUNT_INSN_SIZE +.endm + .macro __mcount suffix mcount_enter ldr r0, =ftrace_trace_function @@ -173,8 +178,7 @@ ENDPROC(ret_from_fork) mcount_exit 1: mcount_get_lr r1 @ lr of instrumented func - mov r0, lr @ instrumented function - sub r0, r0, #MCOUNT_INSN_SIZE + mcount_adjust_addr r0, lr @ instrumented function adr lr, BSYM(2f) mov pc, r2 2: mcount_exit @@ -184,8 +188,7 @@ ENDPROC(ret_from_fork) mcount_enter mcount_get_lr r1 @ lr of instrumented func - mov r0, lr @ instrumented function - sub r0, r0, #MCOUNT_INSN_SIZE + mcount_adjust_addr r0, lr @ instrumented function .globl ftrace_call\suffix ftrace_call\suffix: @@ -205,11 +208,11 @@ ftrace_graph_call\suffix: #ifdef CONFIG_DYNAMIC_FTRACE @ called from __ftrace_caller, saved in mcount_enter ldr r1, [sp, #16] @ instrumented routine (func) + mcount_adjust_addr r1, r1 #else @ called from __mcount, untouched in lr - mov r1, lr @ instrumented routine (func) + mcount_adjust_addr r1, lr @ instrumented routine (func) #endif - sub r1, r1, #MCOUNT_INSN_SIZE mov r2, fp @ frame pointer bl prepare_ftrace_return mcount_exit -- GitLab