Re: [RFC v2 PATCH 1/1] ARM64: KGDB: Add FP/SIMD debug support

On Mon, Nov 18, 2013 at 12:06:57PM +0000, vijay.kilari@gmail.com wrote:

From: Vijaya Kumar K Vijaya.Kumar@caviumnetworks.com

Add KGDB debug support for FP/SIMD processor.This support only debugging of FP/SIMD in kernel mode. With this patch one can view or set FP/SIMD registers in kernel context

Signed-off-by: Vijaya Kumar K Vijaya.Kumar@caviumnetworks.com

arch/arm64/include/asm/fpsimd.h | 1 + arch/arm64/kernel/fpsimd.c | 5 ++ arch/arm64/kernel/kgdb.c | 105 +++++++++++++++++++++++++-------------- 3 files changed, 73 insertions(+), 38 deletions(-)

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h index 609bc44..5039d6d 100644 --- a/arch/arm64/include/asm/fpsimd.h +++ b/arch/arm64/include/asm/fpsimd.h @@ -60,6 +60,7 @@ extern void fpsimd_load_state(struct fpsimd_state *state); extern void fpsimd_thread_switch(struct task_struct *next); extern void fpsimd_flush_thread(void); extern void fpsimd_reload_fpstate(void); +extern int fpsimd_thread_state(void); #endif diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c index 5b13c17..27604c1 100644 --- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -124,6 +124,11 @@ void fpsimd_flush_thread(void) set_thread_flag(TIF_FOREIGN_FPSTATE); } +int fpsimd_thread_state(void) +{

• return (current->mm && test_thread_flag(TIF_FOREIGN_FPSTATE)) ? 1 : 0;

+}

Erm...

1. `? 1 : 0' doesn't do anything 2. TIF_FOREIGN_FPSTATE doesn't seem to appear in my source tree (3.13-rc1) 3. Does it make sense for threads without an mm to have TIF_FOREIGN_FPSTATE set?

void fpsimd_reload_fpstate(void) { preempt_disable(); diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index f10f2ba..5e34852 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -23,6 +23,14 @@ #include <linux/kdebug.h> #include <linux/kgdb.h> #include <asm/traps.h> +#include <asm/fpsimd.h>

+#ifdef CONFIG_KERNEL_MODE_NEON +/*

• • Structure to hold FP/SIMD register contents
• */

+struct fpsimd_state kgdb_fpsimd_regs; +#endif struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { { "x0", 8, offsetof(struct pt_regs, regs[0])}, @@ -59,40 +67,40 @@ struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { { "sp", 8, offsetof(struct pt_regs, sp)}, { "pc", 8, offsetof(struct pt_regs, pc)}, { "pstate", 4, offsetof(struct pt_regs, pstate)},

• { "v0", 16, -1 },
• { "v1", 16, -1 },
• { "v2", 16, -1 },
• { "v3", 16, -1 },
• { "v4", 16, -1 },
• { "v5", 16, -1 },
• { "v6", 16, -1 },
• { "v7", 16, -1 },
• { "v8", 16, -1 },
• { "v9", 16, -1 },
• { "v10", 16, -1 },
• { "v11", 16, -1 },
• { "v12", 16, -1 },
• { "v13", 16, -1 },
• { "v14", 16, -1 },
• { "v15", 16, -1 },
• { "v16", 16, -1 },
• { "v17", 16, -1 },
• { "v18", 16, -1 },
• { "v19", 16, -1 },
• { "v20", 16, -1 },
• { "v21", 16, -1 },
• { "v22", 16, -1 },
• { "v23", 16, -1 },
• { "v24", 16, -1 },
• { "v25", 16, -1 },
• { "v26", 16, -1 },
• { "v27", 16, -1 },
• { "v28", 16, -1 },
• { "v29", 16, -1 },
• { "v30", 16, -1 },
• { "v31", 16, -1 },
• { "fpsr", 4, -1 },
• { "fpcr", 4, -1 },

• { "v0", 16, offsetof(struct fpsimd_state, vregs[0])},
• { "v1", 16, offsetof(struct fpsimd_state, vregs[1])},
• { "v2", 16, offsetof(struct fpsimd_state, vregs[2])},
• { "v3", 16, offsetof(struct fpsimd_state, vregs[3])},
• { "v4", 16, offsetof(struct fpsimd_state, vregs[4])},
• { "v5", 16, offsetof(struct fpsimd_state, vregs[5])},
• { "v6", 16, offsetof(struct fpsimd_state, vregs[6])},
• { "v7", 16, offsetof(struct fpsimd_state, vregs[7])},
• { "v8", 16, offsetof(struct fpsimd_state, vregs[8])},
• { "v9", 16, offsetof(struct fpsimd_state, vregs[9])},
• { "v10", 16, offsetof(struct fpsimd_state, vregs[10])},
• { "v11", 16, offsetof(struct fpsimd_state, vregs[11])},
• { "v12", 16, offsetof(struct fpsimd_state, vregs[12])},
• { "v13", 16, offsetof(struct fpsimd_state, vregs[13])},
• { "v14", 16, offsetof(struct fpsimd_state, vregs[14])},
• { "v15", 16, offsetof(struct fpsimd_state, vregs[15])},
• { "v16", 16, offsetof(struct fpsimd_state, vregs[16])},
• { "v17", 16, offsetof(struct fpsimd_state, vregs[17])},
• { "v18", 16, offsetof(struct fpsimd_state, vregs[18])},
• { "v19", 16, offsetof(struct fpsimd_state, vregs[19])},
• { "v20", 16, offsetof(struct fpsimd_state, vregs[20])},
• { "v21", 16, offsetof(struct fpsimd_state, vregs[21])},
• { "v22", 16, offsetof(struct fpsimd_state, vregs[22])},
• { "v23", 16, offsetof(struct fpsimd_state, vregs[23])},
• { "v24", 16, offsetof(struct fpsimd_state, vregs[24])},
• { "v25", 16, offsetof(struct fpsimd_state, vregs[25])},
• { "v26", 16, offsetof(struct fpsimd_state, vregs[26])},
• { "v27", 16, offsetof(struct fpsimd_state, vregs[27])},
• { "v28", 16, offsetof(struct fpsimd_state, vregs[28])},
• { "v29", 16, offsetof(struct fpsimd_state, vregs[29])},
• { "v30", 16, offsetof(struct fpsimd_state, vregs[30])},
• { "v31", 16, offsetof(struct fpsimd_state, vregs[31])},
• { "fpsr", 4, offsetof(struct fpsimd_state, fpsr)},
• { "fpcr", 4, offsetof(struct fpsimd_state, fpcr)},

}; char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) @@ -100,11 +108,22 @@ char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) if (regno >= DBG_MAX_REG_NUM || regno < 0) return NULL;

• if (dbg_reg_def[regno].offset != -1)

• if (dbg_reg_def[regno].offset != -1 && regno < _GP_REGS) memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, dbg_reg_def[regno].size);

• else

• else {

+#ifdef CONFIG_KERNEL_MODE_NEON

• if (fpsimd_thread_state()) {
  

• 	fpsimd_save_state(&kgdb_fpsimd_regs);
  

• 	memcpy(mem, (void *)&kgdb_fpsimd_regs +
  

• 			dbg_reg_def[regno].offset,
  

• 			dbg_reg_def[regno].size);
  

• } else
  

• 	memset(mem, 0, dbg_reg_def[regno].size);
  

+#else memset(mem, 0, dbg_reg_def[regno].size);

Can you use IS_ENABLED to tidy this up?

Will