Patchwork [v1,3/6] book3e/kgdb: update thread's dbcr0

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Submitter Tiejun Chen
Date Dec. 20, 2012, 9:08 a.m.
Message ID <1355994510-11934-4-git-send-email-tiejun.chen@windriver.com>
Download mbox | patch
Permalink /patch/207627/
State Superseded
Headers show

Comments

Tiejun Chen - Dec. 20, 2012, 9:08 a.m.
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 |   10 ++++++++++
 1 file changed, 10 insertions(+)
Kumar Gala - Dec. 20, 2012, 6:41 p.m.
On Dec 20, 2012, at 3:08 AM, 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.
> 
> 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 |   10 ++++++++++
> 1 file changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
> index c470a40..516b44b 100644
> --- a/arch/powerpc/kernel/kgdb.c
> +++ b/arch/powerpc/kernel/kgdb.c
> @@ -426,8 +426,18 @@ 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
> +#ifdef CONFIG_PPC_BOOK3E

Should this really be CONFIG_PPC64 or 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 =
> +				mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM;
> +			mtspr(SPRN_DBCR0, current->thread.dbcr0);
> +#else
> 			mtspr(SPRN_DBCR0,
> 			      mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
> +#endif

Can we code this so we don't need the #else?

> 			linux_regs->msr |= MSR_DE;
> #else
> 			linux_regs->msr |= MSR_SE;
> -- 
> 1.7.9.5
> 
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Patch

diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c
index c470a40..516b44b 100644
--- a/arch/powerpc/kernel/kgdb.c
+++ b/arch/powerpc/kernel/kgdb.c
@@ -426,8 +426,18 @@  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
+#ifdef CONFIG_PPC_BOOK3E
+			/* 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 =
+				mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM;
+			mtspr(SPRN_DBCR0, current->thread.dbcr0);
+#else
 			mtspr(SPRN_DBCR0,
 			      mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
+#endif
 			linux_regs->msr |= MSR_DE;
 #else
 			linux_regs->msr |= MSR_SE;