Messages in this thread | | | Subject | Re: [PATCH 07/15] powerpc/watchpoint: Get watchpoint count dynamically while disabling them | From | Ravi Bangoria <> | Date | Thu, 26 Mar 2020 09:02:05 +0530 |
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On 3/18/20 12:27 PM, Ravi Bangoria wrote: > > > On 3/17/20 4:02 PM, Christophe Leroy wrote: >> >> >> Le 09/03/2020 à 09:57, Ravi Bangoria a écrit : >>> Instead of disabling only one watchpooint, get num of available >>> watchpoints dynamically and disable all of them. >>> >>> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> >>> --- >>> arch/powerpc/include/asm/hw_breakpoint.h | 15 +++++++-------- >>> 1 file changed, 7 insertions(+), 8 deletions(-) >>> >>> diff --git a/arch/powerpc/include/asm/hw_breakpoint.h b/arch/powerpc/include/asm/hw_breakpoint.h >>> index 980ac7d9f267..ec61e2b7195c 100644 >>> --- a/arch/powerpc/include/asm/hw_breakpoint.h >>> +++ b/arch/powerpc/include/asm/hw_breakpoint.h >>> @@ -75,14 +75,13 @@ extern void ptrace_triggered(struct perf_event *bp, >>> struct perf_sample_data *data, struct pt_regs *regs); >>> static inline void hw_breakpoint_disable(void) >>> { >>> - struct arch_hw_breakpoint brk; >>> - >>> - brk.address = 0; >>> - brk.type = 0; >>> - brk.len = 0; >>> - brk.hw_len = 0; >>> - if (ppc_breakpoint_available()) >>> - __set_breakpoint(&brk, 0); >>> + int i; >>> + struct arch_hw_breakpoint null_brk = {0}; >>> + >>> + if (ppc_breakpoint_available()) { >> >> I think this test should go into nr_wp_slots() which should return zero when no breakpoint is available. > > Seems possible. Will change it in next version.
Once we move ppc_breakpoint_available() logic into nr_wp_slots(), 'dawr_force_enable' variable is checked in nr_wp_slots() before it gets initialized in dawr_force_setup():
start_kernel() |-> perf_event_init() | init_hw_breakpoint() | hw_breakpoint_slots() | nr_wp_slots() | /* Check dawr_force_enable variable */ | |-> arch_call_rest_init() rest_init() kernel_thread(kernel_init, ...) ... kernel_init() kernel_init_freeable() ... do_one_initcall() dawr_force_setup() /* Set dawr_force_enable = true */
Because of this, hw-breakpoint infrastructure is initialized with no DAWRs. So I'm thinking to keep the code as it is i.e. not moving ppc_breakpoint_available() test inside nr_wp_slots().
Ravi
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