From ec097c84dff17511f2693e6ef6c3064dfbf0a3af Mon Sep 17 00:00:00 2001 From: Roland McGrath Date: Thu, 28 May 2009 21:26:38 +0000 Subject: [PATCH] powerpc: Add PTRACE_SINGLEBLOCK support Reworked by: Benjamin Herrenschmidt This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK request for ptrace. The BookE implementation is tweaked to fire a single step after a block step in order to mimmic the server behaviour. Signed-off-by: Roland McGrath Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/include/asm/ptrace.h | 4 ++++ arch/powerpc/kernel/head_booke.h | 10 ++++----- arch/powerpc/kernel/ptrace.c | 23 +++++++++++++++++++-- arch/powerpc/kernel/traps.c | 34 +++++++++++++++++++++++++++---- 4 files changed, 60 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/include/asm/ptrace.h b/arch/powerpc/include/asm/ptrace.h index c9c678fb2538..8c341490cfc5 100644 --- a/arch/powerpc/include/asm/ptrace.h +++ b/arch/powerpc/include/asm/ptrace.h @@ -135,7 +135,9 @@ do { \ * These are defined as per linux/ptrace.h, which see. */ #define arch_has_single_step() (1) +#define arch_has_block_step() (!cpu_has_feature(CPU_FTR_601)) extern void user_enable_single_step(struct task_struct *); +extern void user_enable_block_step(struct task_struct *); extern void user_disable_single_step(struct task_struct *); #endif /* __ASSEMBLY__ */ @@ -288,4 +290,6 @@ extern void user_disable_single_step(struct task_struct *); #define PPC_PTRACE_PEEKUSR_3264 0x91 #define PPC_PTRACE_POKEUSR_3264 0x90 +#define PTRACE_SINGLEBLOCK 0x100 /* resume execution until next branch */ + #endif /* _ASM_POWERPC_PTRACE_H */ diff --git a/arch/powerpc/kernel/head_booke.h b/arch/powerpc/kernel/head_booke.h index 95f39f1e68d4..5f9febc8d143 100644 --- a/arch/powerpc/kernel/head_booke.h +++ b/arch/powerpc/kernel/head_booke.h @@ -256,7 +256,7 @@ label: * off DE in the DSRR1 value and clearing the debug status. \ */ \ mfspr r10,SPRN_DBSR; /* check single-step/branch taken */ \ - andis. r10,r10,DBSR_IC@h; \ + andis. r10,r10,(DBSR_IC|DBSR_BT)@h; \ beq+ 2f; \ \ lis r10,KERNELBASE@h; /* check if exception in vectors */ \ @@ -271,7 +271,7 @@ label: \ /* here it looks like we got an inappropriate debug exception. */ \ 1: rlwinm r9,r9,0,~MSR_DE; /* clear DE in the CDRR1 value */ \ - lis r10,DBSR_IC@h; /* clear the IC event */ \ + lis r10,(DBSR_IC|DBSR_BT)@h; /* clear the IC event */ \ mtspr SPRN_DBSR,r10; \ /* restore state and get out */ \ lwz r10,_CCR(r11); \ @@ -309,7 +309,7 @@ label: * off DE in the CSRR1 value and clearing the debug status. \ */ \ mfspr r10,SPRN_DBSR; /* check single-step/branch taken */ \ - andis. r10,r10,DBSR_IC@h; \ + andis. r10,r10,(DBSR_IC|DBSR_BT)@h; \ beq+ 2f; \ \ lis r10,KERNELBASE@h; /* check if exception in vectors */ \ @@ -317,14 +317,14 @@ label: cmplw r12,r10; \ blt+ 2f; /* addr below exception vectors */ \ \ - lis r10,DebugCrit@h; \ + lis r10,DebugCrit@h; \ ori r10,r10,DebugCrit@l; \ cmplw r12,r10; \ bgt+ 2f; /* addr above exception vectors */ \ \ /* here it looks like we got an inappropriate debug exception. */ \ 1: rlwinm r9,r9,0,~MSR_DE; /* clear DE in the CSRR1 value */ \ - lis r10,DBSR_IC@h; /* clear the IC event */ \ + lis r10,(DBSR_IC|DBSR_BT)@h; /* clear the IC event */ \ mtspr SPRN_DBSR,r10; \ /* restore state and get out */ \ lwz r10,_CCR(r11); \ diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index 3635be61f899..9fa2c7dcd05a 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -704,15 +704,34 @@ void user_enable_single_step(struct task_struct *task) if (regs != NULL) { #if defined(CONFIG_40x) || defined(CONFIG_BOOKE) + task->thread.dbcr0 &= ~DBCR0_BT; task->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC; regs->msr |= MSR_DE; #else + regs->msr &= ~MSR_BE; regs->msr |= MSR_SE; #endif } set_tsk_thread_flag(task, TIF_SINGLESTEP); } +void user_enable_block_step(struct task_struct *task) +{ + struct pt_regs *regs = task->thread.regs; + + if (regs != NULL) { +#if defined(CONFIG_40x) || defined(CONFIG_BOOKE) + task->thread.dbcr0 &= ~DBCR0_IC; + task->thread.dbcr0 = DBCR0_IDM | DBCR0_BT; + regs->msr |= MSR_DE; +#else + regs->msr &= ~MSR_SE; + regs->msr |= MSR_BE; +#endif + } + set_tsk_thread_flag(task, TIF_SINGLESTEP); +} + void user_disable_single_step(struct task_struct *task) { struct pt_regs *regs = task->thread.regs; @@ -726,10 +745,10 @@ void user_disable_single_step(struct task_struct *task) if (regs != NULL) { #if defined(CONFIG_40x) || defined(CONFIG_BOOKE) - task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_IDM); + task->thread.dbcr0 &= ~(DBCR0_IC | DBCR0_BT | DBCR0_IDM); regs->msr &= ~MSR_DE; #else - regs->msr &= ~MSR_SE; + regs->msr &= ~(MSR_SE | MSR_BE); #endif } clear_tsk_thread_flag(task, TIF_SINGLESTEP); diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index 6a5b2b731f43..6f0ae1a9bfae 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -1041,7 +1041,34 @@ void SoftwareEmulation(struct pt_regs *regs) void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status) { - if (debug_status & DBSR_IC) { /* instruction completion */ + /* Hack alert: On BookE, Branch Taken stops on the branch itself, while + * on server, it stops on the target of the branch. In order to simulate + * the server behaviour, we thus restart right away with a single step + * instead of stopping here when hitting a BT + */ + if (debug_status & DBSR_BT) { + regs->msr &= ~MSR_DE; + + /* Disable BT */ + mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_BT); + /* Clear the BT event */ + mtspr(SPRN_DBSR, DBSR_BT); + + /* Do the single step trick only when coming from userspace */ + if (user_mode(regs)) { + current->thread.dbcr0 &= ~DBCR0_BT; + current->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC; + regs->msr |= MSR_DE; + return; + } + + if (notify_die(DIE_SSTEP, "block_step", regs, 5, + 5, SIGTRAP) == NOTIFY_STOP) { + return; + } + if (debugger_sstep(regs)) + return; + } else if (debug_status & DBSR_IC) { /* Instruction complete */ regs->msr &= ~MSR_DE; /* Disable instruction completion */ @@ -1057,9 +1084,8 @@ void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status) if (debugger_sstep(regs)) return; - if (user_mode(regs)) { - current->thread.dbcr0 &= ~DBCR0_IC; - } + if (user_mode(regs)) + current->thread.dbcr0 &= ~(DBCR0_IC); _exception(SIGTRAP, regs, TRAP_TRACE, regs->nip); } else if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) { -- 2.34.1