| Message ID | 4f88d7e6fda53b5f80a71040ab400242f6c8cb93.1566400889.git.christophe.leroy@c-s.fr (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 46ddcb3950a28c0df4815e8dbb8d4b91d5d9f22d |
| Headers | show |
| Series | powerpc/mm: tell if a bad page fault on data is read or write. | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/apply_patch | success | Successfully applied on branch next (0e4523c0b4f64eaf7abe59e143e6bdf8f972acff) |
| snowpatch_ozlabs/build-ppc64le | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64be | success | Build succeeded |
| snowpatch_ozlabs/build-ppc64e | success | Build succeeded |
| snowpatch_ozlabs/build-pmac32 | success | Build succeeded |
| snowpatch_ozlabs/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 19 lines checked |
Christophe Leroy <christophe.leroy@c-s.fr> writes: > DSISR has a bit to tell if the fault is due to a read or a write. > > Display it. > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Reviewed-by: Santosh Sivaraj <santosh@fossix.org> > --- > arch/powerpc/mm/fault.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index 8432c281de92..b5047f9b5dec 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -645,6 +645,7 @@ NOKPROBE_SYMBOL(do_page_fault); > void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) > { > const struct exception_table_entry *entry; > + int is_write = page_fault_is_write(regs->dsisr); > > /* Are we prepared to handle this fault? */ > if ((entry = search_exception_tables(regs->nip)) != NULL) { > @@ -658,9 +659,10 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) > case 0x300: > case 0x380: > case 0xe00: > - pr_alert("BUG: %s at 0x%08lx\n", > + pr_alert("BUG: %s on %s at 0x%08lx\n", > regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : > - "Unable to handle kernel data access", regs->dar); > + "Unable to handle kernel data access", > + is_write ? "write" : "read", regs->dar); > break; > case 0x400: > case 0x480: > -- > 2.13.3
Christophe Leroy <christophe.leroy@c-s.fr> writes: > DSISR has a bit to tell if the fault is due to a read or a write. Except some CPUs don't have a DSISR? Which is why we have page_fault_is_write() that's used in __do_page_fault(). Or is that old cruft? I see eg. in head_40x.S we pass r5=0 for error code, and we don't set regs->dsisr anywhere AFAICS. So it might just contain some junk. cheers > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > index 8432c281de92..b5047f9b5dec 100644 > --- a/arch/powerpc/mm/fault.c > +++ b/arch/powerpc/mm/fault.c > @@ -645,6 +645,7 @@ NOKPROBE_SYMBOL(do_page_fault); > void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) > { > const struct exception_table_entry *entry; > + int is_write = page_fault_is_write(regs->dsisr); > > /* Are we prepared to handle this fault? */ > if ((entry = search_exception_tables(regs->nip)) != NULL) { > @@ -658,9 +659,10 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) > case 0x300: > case 0x380: > case 0xe00: > - pr_alert("BUG: %s at 0x%08lx\n", > + pr_alert("BUG: %s on %s at 0x%08lx\n", > regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : > - "Unable to handle kernel data access", regs->dar); > + "Unable to handle kernel data access", > + is_write ? "write" : "read", regs->dar); > break; > case 0x400: > case 0x480: > -- > 2.13.3
Le 29/08/2019 à 14:14, Michael Ellerman a écrit : > Christophe Leroy <christophe.leroy@c-s.fr> writes: >> DSISR has a bit to tell if the fault is due to a read or a write. > > Except some CPUs don't have a DSISR? > > Which is why we have page_fault_is_write() that's used in > __do_page_fault(). > > Or is that old cruft? > > I see eg. in head_40x.S we pass r5=0 for error code, and we don't set > regs->dsisr anywhere AFAICS. So it might just contain some junk. But then we have a problem with show_regs() as well, havent't we ? if (trap == 0x200 || trap == 0x300 || trap == 0x600) #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) pr_cont("DEAR: "REG" ESR: "REG" ", regs->dar, regs->dsisr); #else pr_cont("DAR: "REG" DSISR: %08lx ", regs->dar, regs->dsisr); #endif I need to look closer. Christophe > > cheers > >> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c >> index 8432c281de92..b5047f9b5dec 100644 >> --- a/arch/powerpc/mm/fault.c >> +++ b/arch/powerpc/mm/fault.c >> @@ -645,6 +645,7 @@ NOKPROBE_SYMBOL(do_page_fault); >> void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) >> { >> const struct exception_table_entry *entry; >> + int is_write = page_fault_is_write(regs->dsisr); >> >> /* Are we prepared to handle this fault? */ >> if ((entry = search_exception_tables(regs->nip)) != NULL) { >> @@ -658,9 +659,10 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) >> case 0x300: >> case 0x380: >> case 0xe00: >> - pr_alert("BUG: %s at 0x%08lx\n", >> + pr_alert("BUG: %s on %s at 0x%08lx\n", >> regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : >> - "Unable to handle kernel data access", regs->dar); >> + "Unable to handle kernel data access", >> + is_write ? "write" : "read", regs->dar); > >> break; >> case 0x400: >> case 0x480: >> -- >> 2.13.3
Le 29/08/2019 à 14:14, Michael Ellerman a écrit : > Christophe Leroy <christophe.leroy@c-s.fr> writes: >> DSISR has a bit to tell if the fault is due to a read or a write. > > Except some CPUs don't have a DSISR? > > Which is why we have page_fault_is_write() that's used in > __do_page_fault(). And that's why I'm also using page_fault_is_write() in my patch. > > Or is that old cruft? > > I see eg. in head_40x.S we pass r5=0 for error code, and we don't set > regs->dsisr anywhere AFAICS. So it might just contain some junk. We pass r5=0 in ISI but r5=SPRN_ESR in DSI. And r5 is also saved into _ESR(r11) And in asm-offset.c, we have: STACK_PT_REGS_OFFSET(_ESR, dsisr); So regs->dsisr has the expected content. Christophe > > cheers > >> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c >> index 8432c281de92..b5047f9b5dec 100644 >> --- a/arch/powerpc/mm/fault.c >> +++ b/arch/powerpc/mm/fault.c >> @@ -645,6 +645,7 @@ NOKPROBE_SYMBOL(do_page_fault); >> void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) >> { >> const struct exception_table_entry *entry; >> + int is_write = page_fault_is_write(regs->dsisr); >> >> /* Are we prepared to handle this fault? */ >> if ((entry = search_exception_tables(regs->nip)) != NULL) { >> @@ -658,9 +659,10 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) >> case 0x300: >> case 0x380: >> case 0xe00: >> - pr_alert("BUG: %s at 0x%08lx\n", >> + pr_alert("BUG: %s on %s at 0x%08lx\n", >> regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : >> - "Unable to handle kernel data access", regs->dar); >> + "Unable to handle kernel data access", >> + is_write ? "write" : "read", regs->dar); > >> break; >> case 0x400: >> case 0x480: >> -- >> 2.13.3
On Wed, 2019-08-21 at 15:21:55 UTC, Christophe Leroy wrote: > DSISR has a bit to tell if the fault is due to a read or a write. > > Display it. > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/46ddcb3950a28c0df4815e8dbb8d4b91d5d9f22d cheers
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 8432c281de92..b5047f9b5dec 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -645,6 +645,7 @@ NOKPROBE_SYMBOL(do_page_fault); void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) { const struct exception_table_entry *entry; + int is_write = page_fault_is_write(regs->dsisr); /* Are we prepared to handle this fault? */ if ((entry = search_exception_tables(regs->nip)) != NULL) { @@ -658,9 +659,10 @@ void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) case 0x300: case 0x380: case 0xe00: - pr_alert("BUG: %s at 0x%08lx\n", + pr_alert("BUG: %s on %s at 0x%08lx\n", regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" : - "Unable to handle kernel data access", regs->dar); + "Unable to handle kernel data access", + is_write ? "write" : "read", regs->dar); break; case 0x400: case 0x480:
DSISR has a bit to tell if the fault is due to a read or a write. Display it. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> --- arch/powerpc/mm/fault.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)