From ec6aba3d2be1ed75b3f4c894bb64a36d40db1f55 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 25 May 2021 09:25:19 +0200 Subject: kprobes: Remove kprobe::fault_handler The reason for kprobe::fault_handler(), as given by their comment: * We come here because instructions in the pre/post * handler caused the page_fault, this could happen * if handler tries to access user space by * copy_from_user(), get_user() etc. Let the * user-specified handler try to fix it first. Is just plain bad. Those other handlers are ran from non-preemptible context and had better use _nofault() functions. Also, there is no upstream usage of this. Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Christoph Hellwig Acked-by: Masami Hiramatsu Link: https://lore.kernel.org/r/20210525073213.561116662@infradead.org --- arch/arc/kernel/kprobes.c | 10 ---------- arch/arm/probes/kprobes/core.c | 9 --------- arch/arm64/kernel/probes/kprobes.c | 10 ---------- arch/csky/kernel/probes/kprobes.c | 10 ---------- arch/ia64/kernel/kprobes.c | 9 --------- arch/mips/kernel/kprobes.c | 3 --- arch/powerpc/kernel/kprobes.c | 10 ---------- arch/riscv/kernel/probes/kprobes.c | 10 ---------- arch/s390/kernel/kprobes.c | 10 ---------- arch/sh/kernel/kprobes.c | 10 ---------- arch/sparc/kernel/kprobes.c | 10 ---------- arch/x86/kernel/kprobes/core.c | 10 ---------- 12 files changed, 111 deletions(-) (limited to 'arch') diff --git a/arch/arc/kernel/kprobes.c b/arch/arc/kernel/kprobes.c index cabef45f11df..9f5b39f38736 100644 --- a/arch/arc/kernel/kprobes.c +++ b/arch/arc/kernel/kprobes.c @@ -323,16 +323,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned long trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned zero, * try to fix up. diff --git a/arch/arm/probes/kprobes/core.c b/arch/arm/probes/kprobes/core.c index a9653117ca0d..7b9b9a5a409b 100644 --- a/arch/arm/probes/kprobes/core.c +++ b/arch/arm/probes/kprobes/core.c @@ -358,15 +358,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) - return 1; break; default: diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c index d607c9912025..f6b088e9fa70 100644 --- a/arch/arm64/kernel/probes/kprobes.c +++ b/arch/arm64/kernel/probes/kprobes.c @@ -283,16 +283,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int fsr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, fsr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/csky/kernel/probes/kprobes.c b/arch/csky/kernel/probes/kprobes.c index 589f090f48b9..e0e973e49770 100644 --- a/arch/csky/kernel/probes/kprobes.c +++ b/arch/csky/kernel/probes/kprobes.c @@ -301,16 +301,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/ia64/kernel/kprobes.c b/arch/ia64/kernel/kprobes.c index fc1ff8a4d7de..6efed4ecff9e 100644 --- a/arch/ia64/kernel/kprobes.c +++ b/arch/ia64/kernel/kprobes.c @@ -850,15 +850,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/mips/kernel/kprobes.c b/arch/mips/kernel/kprobes.c index 54dfba8fa77c..75bff0f77319 100644 --- a/arch/mips/kernel/kprobes.c +++ b/arch/mips/kernel/kprobes.c @@ -403,9 +403,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) struct kprobe *cur = kprobe_running(); struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - if (kcb->kprobe_status & KPROBE_HIT_SS) { resume_execution(cur, regs, kcb); regs->cp0_status |= kcb->kprobe_old_SR; diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 01ab2163659e..75b4e874269d 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -508,16 +508,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c index 10b965c34536..923b5ea396ea 100644 --- a/arch/riscv/kernel/probes/kprobes.c +++ b/arch/riscv/kernel/probes/kprobes.c @@ -283,16 +283,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c index aae24dc75df6..ad631e33df24 100644 --- a/arch/s390/kernel/kprobes.c +++ b/arch/s390/kernel/kprobes.c @@ -452,16 +452,6 @@ static int kprobe_trap_handler(struct pt_regs *regs, int trapnr) */ kprobes_inc_nmissed_count(p); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (p->fault_handler && p->fault_handler(p, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/sh/kernel/kprobes.c b/arch/sh/kernel/kprobes.c index 756100b01e84..58263420ad2a 100644 --- a/arch/sh/kernel/kprobes.c +++ b/arch/sh/kernel/kprobes.c @@ -389,16 +389,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/sparc/kernel/kprobes.c b/arch/sparc/kernel/kprobes.c index 217c21a6986a..db4e341b4b6e 100644 --- a/arch/sparc/kernel/kprobes.c +++ b/arch/sparc/kernel/kprobes.c @@ -352,16 +352,6 @@ int __kprobes kprobe_fault_handler(struct pt_regs *regs, int trapnr) */ kprobes_inc_nmissed_count(cur); - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; - /* * In case the user-specified fault handler returned * zero, try to fix up. diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index d3d65545cb8b..cfcdf4b8a306 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -1110,16 +1110,6 @@ int kprobe_fault_handler(struct pt_regs *regs, int trapnr) * these specific fault cases. */ kprobes_inc_nmissed_count(cur); - - /* - * We come here because instructions in the pre/post - * handler caused the page_fault, this could happen - * if handler tries to access user space by - * copy_from_user(), get_user() etc. Let the - * user-specified handler try to fix it first. - */ - if (cur->fault_handler && cur->fault_handler(cur, regs, trapnr)) - return 1; } return 0; -- cgit v1.2.3