| Message ID | 20170517152336.6052-3-punit.agrawal@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, May 17, 2017 at 04:23:35PM +0100, Punit Agrawal wrote: > From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org> > > Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault > handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar > to VM_FAULT_OOM, the only difference is that a different si_code > (BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is > initialized. > > Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> > Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org> > (fix new __do_user_fault call-site) > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> > Acked-by: Steve Capper <steve.capper@arm.com> > --- > arch/arm64/mm/fault.c | 22 +++++++++++++++++++--- > 1 file changed, 19 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index 37b95dff0b07..a85b44343ac6 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -31,6 +31,7 @@ > #include <linux/highmem.h> > #include <linux/perf_event.h> > #include <linux/preempt.h> > +#include <linux/hugetlb.h> > > #include <asm/bug.h> > #include <asm/cpufeature.h> > @@ -239,10 +240,11 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, > */ > static void __do_user_fault(struct task_struct *tsk, unsigned long addr, > unsigned int esr, unsigned int sig, int code, > - struct pt_regs *regs) > + struct pt_regs *regs, int fault) > { > struct siginfo si; > const struct fault_info *inf; > + unsigned int lsb = 0; > > if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { > inf = esr_to_fault_info(esr); > @@ -259,6 +261,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, > si.si_errno = 0; > si.si_code = code; > si.si_addr = (void __user *)addr; > + /* > + * Either small page or large page may be poisoned. > + * In other words, VM_FAULT_HWPOISON_LARGE and > + * VM_FAULT_HWPOISON are mutually exclusive. > + */ > + if (fault & VM_FAULT_HWPOISON_LARGE) > + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); > + else if (fault & VM_FAULT_HWPOISON) > + lsb = PAGE_SHIFT; > + si.si_addr_lsb = lsb; > + If we're going to start handling poison faults, then we should probably rejig the perf page fault accounting around here so that we follow x86: * Always report PERF_COUNT_SW_PAGE_FAULTS, * Don't report anything else for VM_FAULT_ERROR * Report PERF_COUNT_SW_PAGE_FAULTS_MAJ if VM_FAULT_MAJOR * Otherwise, report PERF_COUNT_SW_PAGE_FAULTS_MIN at the moment, I think you're accounting VM_FAULT_ERROR as PERF_COUNT_SW_PAGE_FAULTS_MIN, which doesn't feel right at all. Will
Will Deacon <will.deacon@arm.com> writes: > On Wed, May 17, 2017 at 04:23:35PM +0100, Punit Agrawal wrote: >> From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org> >> >> Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault >> handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar >> to VM_FAULT_OOM, the only difference is that a different si_code >> (BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is >> initialized. >> >> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> >> Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org> >> (fix new __do_user_fault call-site) >> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> >> Acked-by: Steve Capper <steve.capper@arm.com> >> --- >> arch/arm64/mm/fault.c | 22 +++++++++++++++++++--- >> 1 file changed, 19 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c >> index 37b95dff0b07..a85b44343ac6 100644 >> --- a/arch/arm64/mm/fault.c >> +++ b/arch/arm64/mm/fault.c >> @@ -31,6 +31,7 @@ >> #include <linux/highmem.h> >> #include <linux/perf_event.h> >> #include <linux/preempt.h> >> +#include <linux/hugetlb.h> >> >> #include <asm/bug.h> >> #include <asm/cpufeature.h> >> @@ -239,10 +240,11 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, >> */ >> static void __do_user_fault(struct task_struct *tsk, unsigned long addr, >> unsigned int esr, unsigned int sig, int code, >> - struct pt_regs *regs) >> + struct pt_regs *regs, int fault) >> { >> struct siginfo si; >> const struct fault_info *inf; >> + unsigned int lsb = 0; >> >> if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { >> inf = esr_to_fault_info(esr); >> @@ -259,6 +261,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, >> si.si_errno = 0; >> si.si_code = code; >> si.si_addr = (void __user *)addr; >> + /* >> + * Either small page or large page may be poisoned. >> + * In other words, VM_FAULT_HWPOISON_LARGE and >> + * VM_FAULT_HWPOISON are mutually exclusive. >> + */ >> + if (fault & VM_FAULT_HWPOISON_LARGE) >> + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); >> + else if (fault & VM_FAULT_HWPOISON) >> + lsb = PAGE_SHIFT; >> + si.si_addr_lsb = lsb; >> + > > If we're going to start handling poison faults, then we should probably > rejig the perf page fault accounting around here so that we follow x86: > > * Always report PERF_COUNT_SW_PAGE_FAULTS, > * Don't report anything else for VM_FAULT_ERROR > * Report PERF_COUNT_SW_PAGE_FAULTS_MAJ if VM_FAULT_MAJOR > * Otherwise, report PERF_COUNT_SW_PAGE_FAULTS_MIN > > at the moment, I think you're accounting VM_FAULT_ERROR as > PERF_COUNT_SW_PAGE_FAULTS_MIN, which doesn't feel right at all. Ok. I'd missed the implication of enabling poisoned pages fault handling on the perf accounting. I'll add a patch to update the reporting. > > Will
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 37b95dff0b07..a85b44343ac6 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -31,6 +31,7 @@ #include <linux/highmem.h> #include <linux/perf_event.h> #include <linux/preempt.h> +#include <linux/hugetlb.h> #include <asm/bug.h> #include <asm/cpufeature.h> @@ -239,10 +240,11 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, */ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, unsigned int esr, unsigned int sig, int code, - struct pt_regs *regs) + struct pt_regs *regs, int fault) { struct siginfo si; const struct fault_info *inf; + unsigned int lsb = 0; if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { inf = esr_to_fault_info(esr); @@ -259,6 +261,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, si.si_errno = 0; si.si_code = code; si.si_addr = (void __user *)addr; + /* + * Either small page or large page may be poisoned. + * In other words, VM_FAULT_HWPOISON_LARGE and + * VM_FAULT_HWPOISON are mutually exclusive. + */ + if (fault & VM_FAULT_HWPOISON_LARGE) + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); + else if (fault & VM_FAULT_HWPOISON) + lsb = PAGE_SHIFT; + si.si_addr_lsb = lsb; + force_sig_info(sig, &si, tsk); } @@ -274,7 +287,7 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re */ if (user_mode(regs)) { inf = esr_to_fault_info(esr); - __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs); + __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs, 0); } else __do_kernel_fault(mm, addr, esr, regs); } @@ -461,6 +474,9 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, */ sig = SIGBUS; code = BUS_ADRERR; + } else if (fault & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE)) { + sig = SIGBUS; + code = BUS_MCEERR_AR; } else { /* * Something tried to access memory that isn't in our memory @@ -471,7 +487,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, SEGV_ACCERR : SEGV_MAPERR; } - __do_user_fault(tsk, addr, esr, sig, code, regs); + __do_user_fault(tsk, addr, esr, sig, code, regs, fault); return 0; no_context: