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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: Robin Murphy <robin.murphy@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Robin Murphy 2016-10-18 13:46:27 +01:00 committed by Catalin Marinas
parent be8f185d8a
commit 4890ae4691
1 changed files with 7 additions and 9 deletions
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16
arch/arm64/kernel/probes/simulate-insn.c
View File

@ -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