Messages in this thread | | | Subject | Re: [PATCH v2 13/16] powerpc/watchpoint: Prepare handler to handle more than one watcnhpoint | From | Ravi Bangoria <> | Date | Wed, 1 Apr 2020 14:43:41 +0530 |
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On 4/1/20 12:20 PM, Christophe Leroy wrote: > > > Le 01/04/2020 à 08:13, Ravi Bangoria a écrit : >> Currently we assume that we have only one watchpoint supported by hw. >> Get rid of that assumption and use dynamic loop instead. This should >> make supporting more watchpoints very easy. >> >> With more than one watchpoint, exception handler need to know which >> DAWR caused the exception, and hw currently does not provide it. So >> we need sw logic for the same. To figure out which DAWR caused the >> exception, check all different combinations of user specified range, >> dawr address range, actual access range and dawrx constrains. For ex, >> if user specified range and actual access range overlaps but dawrx is >> configured for readonly watchpoint and the instruction is store, this >> DAWR must not have caused exception. >> >> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> >> --- >> arch/powerpc/include/asm/processor.h | 2 +- >> arch/powerpc/include/asm/sstep.h | 2 + >> arch/powerpc/kernel/hw_breakpoint.c | 396 +++++++++++++++++++++------ >> arch/powerpc/kernel/process.c | 3 - >> 4 files changed, 313 insertions(+), 90 deletions(-) >> > > [...] > >> -static bool >> -dar_range_overlaps(unsigned long dar, int size, struct arch_hw_breakpoint *info) >> +static bool dar_user_range_overlaps(unsigned long dar, int size, >> + struct arch_hw_breakpoint *info) >> { >> return ((dar <= info->address + info->len - 1) && >> (dar + size - 1 >= info->address)); >> } > > Here and several other places, I think it would be more clear if you could avoid the - 1 : > > return ((dar < info->address + info->len) && > (dar + size > info->address));
Ok. see below...
> > >> +static bool dar_in_hw_range(unsigned long dar, struct arch_hw_breakpoint *info) >> +{ >> + unsigned long hw_start_addr, hw_end_addr; >> + >> + hw_start_addr = ALIGN_DOWN(info->address, HW_BREAKPOINT_SIZE); >> + hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE) - 1; >> + >> + return ((hw_start_addr <= dar) && (hw_end_addr >= dar)); >> +} > > hw_end_addr = ALIGN(info->address + info->len, HW_BREAKPOINT_SIZE); > > return ((hw_start_addr <= dar) && (hw_end_addr > dar));
I'm using -1 while calculating end address is to make it inclusive. If I don't use -1, the end address points to a location outside of actual range, i.e. it's not really an end address.
Ravi
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