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Subject[PATCH 2/5] uprobes/x86: Add is_64bit_mm(), kill validate_insn_bits()
1. Extract the ->ia32_compat check from 64bit validate_insn_bits()
into the new helper, is_64bit_mm(), it will have more users.

TODO: this checks is actually wrong if mm owner is X32 task,
we need another fix which changes set_personality_ia32().

TODO: even worse, the whole 64-or-32-bit logic is very broken
and the fix is not simple, we need the nontrivial changes in
the core uprobes code.

2. Kill validate_insn_bits() and change its single caller to use
uprobe_init_insn(is_64bit_mm(mm).

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
---
arch/x86/kernel/uprobes.c | 20 +++++++++-----------
1 files changed, 9 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 68c63ab..5876ba5 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -231,6 +231,11 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
}

#ifdef CONFIG_X86_64
+static inline bool is_64bit_mm(struct mm_struct *mm)
+{
+ return !config_enabled(CONFIG_IA32_EMULATION) ||
+ !mm->context.ia32_compat;
+}
/*
* If arch_uprobe->insn doesn't use rip-relative addressing, return
* immediately. Otherwise, rewrite the instruction so that it accesses
@@ -355,13 +360,11 @@ handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *
*correction += 4;
}
}
-
-static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
+#else /* 32-bit: */
+static inline bool is_64bit_mm(struct mm_struct *mm)
{
- bool x86_64 = !mm->context.ia32_compat;
- return uprobe_init_insn(auprobe, insn, x86_64);
+ return false;
}
-#else /* 32-bit: */
/*
* No RIP-relative addressing on 32-bit
*/
@@ -376,11 +379,6 @@ static void handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *
long *correction)
{
}
-
-static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm, struct insn *insn)
-{
- return uprobe_init_insn(auprobe, insn, false);
-}
#endif /* CONFIG_X86_64 */

struct uprobe_xol_ops {
@@ -614,7 +612,7 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
bool fix_ip = true, fix_call = false;
int ret;

- ret = validate_insn_bits(auprobe, mm, &insn);
+ ret = uprobe_init_insn(auprobe, &insn, is_64bit_mm(mm));
if (ret)
return ret;

--
1.5.5.1


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