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authorMark Rutland <mark.rutland@arm.com>2017-02-09 15:19:18 +0000
committerWill Deacon <will.deacon@arm.com>2017-02-15 12:20:29 +0000
commit6c23e2ff7013be2c4bbcb7b9b3cc27c763348223 (patch)
treeac620cda6fcbcaf0303b62e4e0689c0034e869f1 /arch/arm64
parentf705d954634d161db5923fc86cacf0f9e301f73a (diff)
downloadlinux-6c23e2ff7013be2c4bbcb7b9b3cc27c763348223.tar.bz2
arm64: ptrace: add XZR-safe regs accessors
In A64, XZR and the SP share the same encoding (31), and whether an instruction accesses XZR or SP for a particular register parameter depends on the definition of the instruction. We store the SP in pt_regs::regs[31], and thus when emulating instructions, we must be careful to not erroneously read from or write back to the saved SP. Unfortunately, we often fail to be this careful. In all cases, instructions using a transfer register parameter Xt use this to refer to XZR rather than SP. This patch adds helpers so that we can more easily and consistently handle these cases. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/include/asm/ptrace.h20
1 files changed, 20 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
index 513daf050e84..11403fdd0a50 100644
--- a/arch/arm64/include/asm/ptrace.h
+++ b/arch/arm64/include/asm/ptrace.h
@@ -194,6 +194,26 @@ static inline u64 regs_get_register(struct pt_regs *regs, unsigned int offset)
return val;
}
+/*
+ * Read a register given an architectural register index r.
+ * This handles the common case where 31 means XZR, not SP.
+ */
+static inline unsigned long pt_regs_read_reg(const struct pt_regs *regs, int r)
+{
+ return (r == 31) ? 0 : regs->regs[r];
+}
+
+/*
+ * Write a register given an architectural register index r.
+ * This handles the common case where 31 means XZR, not SP.
+ */
+static inline void pt_regs_write_reg(struct pt_regs *regs, int r,
+ unsigned long val)
+{
+ if (r != 31)
+ regs->regs[r] = val;
+}
+
/* Valid only for Kernel mode traps. */
static inline unsigned long kernel_stack_pointer(struct pt_regs *regs)
{