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powerpc: Add PTRACE_SINGLEBLOCK support

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Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

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 <roland@redhat.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
tirimbino
Roland McGrath 16 years ago committed by Benjamin Herrenschmidt
parent dac4ccfb64
commit ec097c84df
4 changed files with 60 additions and 11 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 4
      arch/powerpc/include/asm/ptrace.h
  2. 10
      arch/powerpc/kernel/head_booke.h
  3. 23
      arch/powerpc/kernel/ptrace.c
  4. 34
      arch/powerpc/kernel/traps.c

4
arch/powerpc/include/asm/ptrace.h
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@ -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 */

10
arch/powerpc/kernel/head_booke.h
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@ -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); \

23
arch/powerpc/kernel/ptrace.c
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@ -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);

34
arch/powerpc/kernel/traps.c
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@ -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)) {

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