Message ID | 1371724110-8250-4-git-send-email-tiejun.chen@windriver.com (mailing list archive) |
---|---|
State | Changes Requested |
Headers | show |
On Thu, 2013-06-20 at 18:28 +0800, Tiejun Chen wrote: > gdb always need to generate a single step properly to invoke > a kgdb state. But with lazy interrupt, book3e can't always > trigger a debug exception with a single step since the current > is blocked for handling those pending exception, then we miss > that expected dbcr configuration at last to generate a debug > exception. What do you mean by "the current is blocked"? Could you explain more clearly what lazy EE has to do with MSR_DE and DBCR0? > So here we also update thread's dbcr0 to make sure the current > can go back with that missed dbcr0 configuration. > > Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com> > --- > arch/powerpc/kernel/kgdb.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c > index c1eef24..55409ac 100644 > --- a/arch/powerpc/kernel/kgdb.c > +++ b/arch/powerpc/kernel/kgdb.c > @@ -410,7 +410,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, > struct pt_regs *linux_regs) > { > char *ptr = &remcom_in_buffer[1]; > - unsigned long addr; > + unsigned long addr, dbcr0; > > switch (remcom_in_buffer[0]) { > /* > @@ -427,8 +427,15 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, > /* set the trace bit if we're stepping */ > if (remcom_in_buffer[0] == 's') { > #ifdef CONFIG_PPC_ADV_DEBUG_REGS > - mtspr(SPRN_DBCR0, > - mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM); > + dbcr0 = mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM; > + mtspr(SPRN_DBCR0, dbcr0); > +#ifdef CONFIG_PPC_BOOK3E_64 This could as well be "CONFIG_PPC64" -- CONFIG_PPC_ADV_DEBUG_REGS implies booke or 40x. Lazy EE is a CONFIG_PPC64 thing, not specifically CONFIG_PPC_BOOK3E_64. > + /* With lazy interrut we have to update thread dbcr0 here s/interrut/interrupts/ > + * to make sure we can set debug properly at last to invoke > + * kgdb again to work well. > + */ > + current->thread.dbcr0 = dbcr0; > +#endif > linux_regs->msr |= MSR_DE; > #else > linux_regs->msr |= MSR_SE; Hmm, what happens here if we enable KGDB on booke without CONFIG_PPC_ADV_DEBUG_REGS? Kconfig doesn't appear to prevent it. -Scott
On 10/19/2013 06:57 AM, Scott Wood wrote: > On Thu, 2013-06-20 at 18:28 +0800, Tiejun Chen wrote: >> gdb always need to generate a single step properly to invoke >> a kgdb state. But with lazy interrupt, book3e can't always >> trigger a debug exception with a single step since the current >> is blocked for handling those pending exception, then we miss >> that expected dbcr configuration at last to generate a debug >> exception. > > What do you mean by "the current is blocked"? Could you explain more > clearly what lazy EE has to do with MSR_DE and DBCR0? > I will go another path to make sure the lazy EE doesn't affect KGDB, so please see next version. Thanks, Tiejun
diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c index c1eef24..55409ac 100644 --- a/arch/powerpc/kernel/kgdb.c +++ b/arch/powerpc/kernel/kgdb.c @@ -410,7 +410,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, struct pt_regs *linux_regs) { char *ptr = &remcom_in_buffer[1]; - unsigned long addr; + unsigned long addr, dbcr0; switch (remcom_in_buffer[0]) { /* @@ -427,8 +427,15 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, /* set the trace bit if we're stepping */ if (remcom_in_buffer[0] == 's') { #ifdef CONFIG_PPC_ADV_DEBUG_REGS - mtspr(SPRN_DBCR0, - mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM); + dbcr0 = mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM; + mtspr(SPRN_DBCR0, dbcr0); +#ifdef CONFIG_PPC_BOOK3E_64 + /* With lazy interrut we have to update thread dbcr0 here + * to make sure we can set debug properly at last to invoke + * kgdb again to work well. + */ + current->thread.dbcr0 = dbcr0; +#endif linux_regs->msr |= MSR_DE; #else linux_regs->msr |= MSR_SE;
gdb always need to generate a single step properly to invoke a kgdb state. But with lazy interrupt, book3e can't always trigger a debug exception with a single step since the current is blocked for handling those pending exception, then we miss that expected dbcr configuration at last to generate a debug exception. So here we also update thread's dbcr0 to make sure the current can go back with that missed dbcr0 configuration. Signed-off-by: Tiejun Chen <tiejun.chen@windriver.com> --- arch/powerpc/kernel/kgdb.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)