From 9aad563d15da07fdd938014e65c1bbc38fcf3f6c Mon Sep 17 00:00:00 2001 From: Salvador Arroyo Date: Thu, 1 Nov 2012 15:45:12 +0100 Subject: [PATCH] mips: code clean up in mips_m4k_debug_entry() function The function mips_ejtag_read_debug() is defined in mips_ejtag.c and is called only by mips_m4k_debug_entry() for reading the CP0 debug register. The comment in this function is obviously wrong. There is a generic function to read CP0 registers with similar code. A call to mips32_cp0_read() should work in the same way. The purpose of reading the debug register is to test if the DSS bit is set and clear the SSt bit. It is faster and easier if the SSt bit is cleared without any check. Remark: DSS bit set only means that a debug single-step exception ocurred, but it is not possible to step over a sdbbp instruction, in this case DSS will not be set and the SSt bit not cleared by code. Resume command at another address will step, so really the behavior is not the same. Change-Id: Ibd35f80e0f7669976d96f4ed813830cecf587971 Signed-off-by: Salvador Arroyo Reviewed-on: http://openocd.zylin.com/950 Tested-by: jenkins Reviewed-by: Spencer Oliver --- src/target/mips_ejtag.c | 23 ----------------------- src/target/mips_ejtag.h | 1 - src/target/mips_m4k.c | 11 ++--------- 3 files changed, 2 insertions(+), 33 deletions(-) diff --git a/src/target/mips_ejtag.c b/src/target/mips_ejtag.c index c2bee941d9..bd7ae14dd7 100644 --- a/src/target/mips_ejtag.c +++ b/src/target/mips_ejtag.c @@ -248,29 +248,6 @@ int mips_ejtag_exit_debug(struct mips_ejtag *ejtag_info) return mips32_pracc_exec(ejtag_info, 1, &inst, 0, NULL, 0, NULL, 0); } -int mips_ejtag_read_debug(struct mips_ejtag *ejtag_info, uint32_t* debug_reg) -{ - /* read ejtag ECR */ - static const uint32_t code[] = { - MIPS32_MTC0(15, 31, 0), /* move $15 to COP0 DeSave */ - MIPS32_LUI(15, UPPER16(MIPS32_PRACC_STACK)), /* $15 = MIPS32_PRACC_STACK */ - MIPS32_ORI(15, 15, LOWER16(MIPS32_PRACC_STACK)), - MIPS32_SW(1, 0, 15), /* sw $1,($15) */ - MIPS32_SW(2, 0, 15), /* sw $2,($15) */ - MIPS32_LUI(1, UPPER16(MIPS32_PRACC_PARAM_OUT)), /* $1 = MIPS32_PRACC_PARAM_OUT */ - MIPS32_ORI(1, 1, LOWER16(MIPS32_PRACC_PARAM_OUT)), - MIPS32_MFC0(2, 23, 0), /* move COP0 Debug to $2 */ - MIPS32_SW(2, 0, 1), - MIPS32_LW(2, 0, 15), - MIPS32_LW(1, 0, 15), - MIPS32_B(NEG16(12)), - MIPS32_MFC0(15, 31, 0), /* move COP0 DeSave to $15 */ - }; - - return mips32_pracc_exec(ejtag_info, ARRAY_SIZE(code), code, - 0, NULL, 1, debug_reg, 1); -} - int mips_ejtag_init(struct mips_ejtag *ejtag_info) { uint32_t ejtag_version; diff --git a/src/target/mips_ejtag.h b/src/target/mips_ejtag.h index be2af27e73..653103cdb6 100644 --- a/src/target/mips_ejtag.h +++ b/src/target/mips_ejtag.h @@ -143,7 +143,6 @@ int mips_ejtag_fastdata_scan(struct mips_ejtag *ejtag_info, int write_t, uint32_ int mips_ejtag_init(struct mips_ejtag *ejtag_info); int mips_ejtag_config_step(struct mips_ejtag *ejtag_info, int enable_step); -int mips_ejtag_read_debug(struct mips_ejtag *ejtag_info, uint32_t* debug_reg); static inline void mips_le_to_h_u32(jtag_callback_data_t arg) { diff --git a/src/target/mips_m4k.c b/src/target/mips_m4k.c index 1a10d5a979..9a3d929c8c 100644 --- a/src/target/mips_m4k.c +++ b/src/target/mips_m4k.c @@ -82,10 +82,9 @@ static int mips_m4k_debug_entry(struct target *target) { struct mips32_common *mips32 = target_to_mips32(target); struct mips_ejtag *ejtag_info = &mips32->ejtag_info; - uint32_t debug_reg; - /* read debug register */ - mips_ejtag_read_debug(ejtag_info, &debug_reg); + /* make sure stepping disabled, SSt bit in CP0 debug register cleared */ + mips_ejtag_config_step(ejtag_info, 0); /* make sure break unit configured */ mips32_configure_break_unit(target); @@ -93,12 +92,6 @@ static int mips_m4k_debug_entry(struct target *target) /* attempt to find halt reason */ mips_m4k_examine_debug_reason(target); - /* clear single step if active */ - if (debug_reg & EJTAG_DEBUG_DSS) { - /* stopped due to single step - clear step bit */ - mips_ejtag_config_step(ejtag_info, 0); - } - mips32_save_context(target); /* default to mips32 isa, it will be changed below if required */ -- 2.30.2