diff options
| author | Peter Zijlstra | 2022-03-08 16:30:32 +0100 |
|---|---|---|
| committer | Peter Zijlstra | 2022-03-15 10:32:38 +0100 |
| commit | cc66bb91457827f62e2b6cb2518666820f0a6c48 (patch) | |
| tree | dcb636aca2a74467522c1d1b6896aa6c530cbac8 /arch | |
| parent | e52fc2cf3f662828cc0d51c4b73bed73ad275fce (diff) | |
x86/ibt,kprobes: Cure sym+0 equals fentry woes
In order to allow kprobes to skip the ENDBR instructions at sym+0 for
X86_KERNEL_IBT builds, change _kprobe_addr() to take an architecture
callback to inspect the function at hand and modify the offset if
needed.
This streamlines the existing interface to cover more cases and
require less hooks. Once PowerPC gets fully converted there will only
be the one arch hook.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220308154318.405947704@infradead.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/kprobes.c | 34 | ||||
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 17 |
2 files changed, 38 insertions, 13 deletions
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 9a492fdec1df..7dae0b01abfb 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -105,6 +105,27 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) return addr; } +static bool arch_kprobe_on_func_entry(unsigned long offset) +{ +#ifdef PPC64_ELF_ABI_v2 +#ifdef CONFIG_KPROBES_ON_FTRACE + return offset <= 16; +#else + return offset <= 8; +#endif +#else + return !offset; +#endif +} + +/* XXX try and fold the magic of kprobe_lookup_name() in this */ +kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, + bool *on_func_entry) +{ + *on_func_entry = arch_kprobe_on_func_entry(offset); + return (kprobe_opcode_t *)(addr + offset); +} + void *alloc_insn_page(void) { void *page; @@ -218,19 +239,6 @@ static nokprobe_inline void set_current_kprobe(struct kprobe *p, struct pt_regs kcb->kprobe_saved_msr = regs->msr; } -bool arch_kprobe_on_func_entry(unsigned long offset) -{ -#ifdef PPC64_ELF_ABI_v2 -#ifdef CONFIG_KPROBES_ON_FTRACE - return offset <= 16; -#else - return offset <= 8; -#endif -#else - return !offset; -#endif -} - void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs) { ri->ret_addr = (kprobe_opcode_t *)regs->link; diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 4d8086a1627e..9ea0e3e79896 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -52,6 +52,7 @@ #include <asm/insn.h> #include <asm/debugreg.h> #include <asm/set_memory.h> +#include <asm/ibt.h> #include "common.h" @@ -294,6 +295,22 @@ static int can_probe(unsigned long paddr) return (addr == paddr); } +/* If x86 supports IBT (ENDBR) it must be skipped. */ +kprobe_opcode_t *arch_adjust_kprobe_addr(unsigned long addr, unsigned long offset, + bool *on_func_entry) +{ + if (is_endbr(*(u32 *)addr)) { + *on_func_entry = !offset || offset == 4; + if (*on_func_entry) + offset = 4; + + } else { + *on_func_entry = !offset; + } + + return (kprobe_opcode_t *)(addr + offset); +} + /* * Copy an instruction with recovering modified instruction by kprobes * and adjust the displacement if the instruction uses the %rip-relative |