[PATCH 2/3] uprobes/core: remove uprobe_opcode_sz

[Srikar Dronamraju]

From: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>

uprobe_opcode_sz refers to the smallest instruction size for that
architecture. UPROBES_BKPT_INSN_SIZE refers to the size of the breakpoint
instruction for that architecture.

For now we are assuming that both uprobe_opcode_sz and
UPROBES_BKPT_INSN_SIZE are the same for all archs and hence removing
uprobe_opcode_sz in favour of UPROBES_BKPT_INSN_SIZE.

However if we have to support architectures where the smallest instruction
size is different from the size of breakpoint instruction, we may have to
re-introduce uprobe_opcode_sz.

Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
 include/linux/uprobes.h |    2 --
 kernel/uprobes.c        |    6 +++---
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index 64e45f1..fd45b70 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -37,8 +37,6 @@ struct uprobe_arch_info {};
 #define MAX_UINSN_BYTES 4
 #endif
 
-#define uprobe_opcode_sz sizeof(uprobe_opcode_t)
-
 /* flags that denote/change uprobes behaviour */
 
 /* Have a copy of original instruction */
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
index 884817f..ee496ad 100644
--- a/kernel/uprobes.c
+++ b/kernel/uprobes.c
@@ -244,8 +244,8 @@ static int write_opcode(struct mm_struct *mm, struct uprobe *uprobe,
 
 	/* poke the new insn in, ASSUMES we don't cross page boundary */
 	vaddr &= ~PAGE_MASK;
-	BUG_ON(vaddr + uprobe_opcode_sz > PAGE_SIZE);
-	memcpy(vaddr_new + vaddr, &opcode, uprobe_opcode_sz);
+	BUG_ON(vaddr + UPROBES_BKPT_INSN_SIZE > PAGE_SIZE);
+	memcpy(vaddr_new + vaddr, &opcode, UPROBES_BKPT_INSN_SIZE);
 
 	kunmap_atomic(vaddr_new);
 	kunmap_atomic(vaddr_old);
@@ -293,7 +293,7 @@ static int read_opcode(struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_
 	lock_page(page);
 	vaddr_new = kmap_atomic(page);
 	vaddr &= ~PAGE_MASK;
-	memcpy(opcode, vaddr_new + vaddr, uprobe_opcode_sz);
+	memcpy(opcode, vaddr_new + vaddr, UPROBES_BKPT_INSN_SIZE);
 	kunmap_atomic(vaddr_new);
 	unlock_page(page);
 


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