Messages in this thread | | | Date | Tue, 31 Mar 2020 11:43:18 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH 10/12] powerpc/entry32: Blacklist exception entry points for kprobe. |
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Christophe Leroy wrote: > > > Le 30/03/2020 à 19:08, Naveen N. Rao a écrit : >> Christophe Leroy wrote: >>> kprobe does not handle events happening in real mode. >>> >>> As exception entry points are running with MMU disabled, >>> blacklist them. >>> >>> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> >>> --- >>> arch/powerpc/kernel/entry_32.S | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> diff --git a/arch/powerpc/kernel/entry_32.S >>> b/arch/powerpc/kernel/entry_32.S >>> index 94f78c03cb79..9a1a45d6038a 100644 >>> --- a/arch/powerpc/kernel/entry_32.S >>> +++ b/arch/powerpc/kernel/entry_32.S >>> @@ -51,6 +51,7 @@ mcheck_transfer_to_handler: >>> mfspr r0,SPRN_DSRR1 >>> stw r0,_DSRR1(r11) >>> /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(mcheck_transfer_to_handler) >>> >>> .globl debug_transfer_to_handler >>> debug_transfer_to_handler: >>> @@ -59,6 +60,7 @@ debug_transfer_to_handler: >>> mfspr r0,SPRN_CSRR1 >>> stw r0,_CSRR1(r11) >>> /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(debug_transfer_to_handler) >>> >>> .globl crit_transfer_to_handler >>> crit_transfer_to_handler: >>> @@ -94,6 +96,7 @@ crit_transfer_to_handler: >>> rlwinm r0,r1,0,0,(31 - THREAD_SHIFT) >>> stw r0,KSP_LIMIT(r8) >>> /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler) >>> #endif >>> >>> #ifdef CONFIG_40x >>> @@ -115,6 +118,7 @@ crit_transfer_to_handler: >>> rlwinm r0,r1,0,0,(31 - THREAD_SHIFT) >>> stw r0,KSP_LIMIT(r8) >>> /* fall through */ >>> +_ASM_NOKPROBE_SYMBOL(crit_transfer_to_handler) >>> #endif >>> >>> /* >>> @@ -127,6 +131,7 @@ crit_transfer_to_handler: >>> .globl transfer_to_handler_full >>> transfer_to_handler_full: >>> SAVE_NVGPRS(r11) >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_full) >>> /* fall through */ >>> >>> .globl transfer_to_handler >>> @@ -286,6 +291,8 @@ reenable_mmu: >>> lwz r2, GPR2(r11) >>> b fast_exception_return >>> #endif >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler) >>> +_ASM_NOKPROBE_SYMBOL(transfer_to_handler_cont) >> >> These are added after 'reenable_mmu', which is itself not blacklisted. >> Is that intentional? > > Yes I put it as the complete end of the entry part, ie just before > stack_ovf which is a function by itself. > > Note that reenable_mmu is inside an #ifdef CONFIG_TRACE_IRQFLAGS. > > I'm not completely sure where to put the _ASM_NOKPROBE_SYMBOL()s, that's > the reason why I put it close to the symbol itself in my first series.
Ok, I see what you mean. 'reenable_mmu' can probably be moved after the end of 'transfer_to_handler_cont' (as also removing what looks to be an unused label '1' for the branch to trace_hardirqs_off), but that's a minor thing. From the blacklisting point, this is not an issue.
- Naveen
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