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Commit 4890ae46 authored by Robin Murphy's avatar Robin Murphy Committed by Catalin Marinas
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arm64/kprobes: Tidy up sign-extension usage 



Kprobes does not need its own homebrewed (and frankly inscrutable) sign
extension macro; just use the standard kernel functions instead. Since
the compiler actually recognises the sign-extension idiom of the latter,
we also get the small bonus of some nicer codegen, as each displacement
calculation helper then compiles to a single optimal SBFX instruction.

Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent be8f185d

arch/arm64/kernel/probes/simulate-insn.c

+7 −9
Original line number Diff line number Diff line
@@ -13,28 +13,26 @@ 
 * General Public License for more details.

 */



#include <linux/bitops.h>

#include <linux/kernel.h>

#include <linux/kprobes.h>



#include "simulate-insn.h"



#define sign_extend(x, signbit)		\

	((x) | (0 - ((x) & (1 << (signbit)))))



#define bbl_displacement(insn)		\

	sign_extend(((insn) & 0x3ffffff) << 2, 27)

	sign_extend32(((insn) & 0x3ffffff) << 2, 27)



#define bcond_displacement(insn)	\

	sign_extend(((insn >> 5) & 0x7ffff) << 2, 20)

	sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)



#define cbz_displacement(insn)	\

	sign_extend(((insn >> 5) & 0x7ffff) << 2, 20)

	sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)



#define tbz_displacement(insn)	\

	sign_extend(((insn >> 5) & 0x3fff) << 2, 15)

	sign_extend32(((insn >> 5) & 0x3fff) << 2, 15)



#define ldr_displacement(insn)	\

	sign_extend(((insn >> 5) & 0x7ffff) << 2, 20)

	sign_extend32(((insn >> 5) & 0x7ffff) << 2, 20)



static inline void set_x_reg(struct pt_regs *regs, int reg, u64 val)

{
@@ -106,7 +104,7 @@ simulate_adr_adrp(u32 opcode, long addr, struct pt_regs *regs) 


	xn = opcode & 0x1f;

	imm = ((opcode >> 3) & 0x1ffffc) | ((opcode >> 29) & 0x3);

	imm = sign_extend(imm, 20);

	imm = sign_extend64(imm, 20);

	if (opcode & 0x80000000)

		val = (imm<<12) + (addr & 0xfffffffffffff000);

	else