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arm64: patching: Add aarch64_insn_write_literal_u64()

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In subsequent patches we'll need to atomically write to a
naturally-aligned 64-bit literal embedded within the kernel text.

Add a helper for this. For consistency with other text patching code we
use copy_to_kernel_nofault(), which is atomic for naturally-aligned
accesses up to 64-bits.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230123134603.1064407-7-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Mark Rutland 2023-01-23 13:46:01 +00:00 committed by Catalin Marinas
parent 2bbbb4015a
commit e4ecbe83fd
2 changed files with 19 additions and 0 deletions
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2
arch/arm64/include/asm/patching.h
View file

@ -7,6 +7,8 @@
int aarch64_insn_read(void *addr, u32 *insnp);
int aarch64_insn_write(void *addr, u32 insn);
int aarch64_insn_write_literal_u64(void *addr, u64 val);
int aarch64_insn_patch_text_nosync(void *addr, u32 insn);
int aarch64_insn_patch_text(void *addrs[], u32 insns[], int cnt);

17
arch/arm64/kernel/patching.c
View file

@ -88,6 +88,23 @@ int __kprobes aarch64_insn_write(void *addr, u32 insn)
return __aarch64_insn_write(addr, cpu_to_le32(insn));
}
noinstr int aarch64_insn_write_literal_u64(void *addr, u64 val)
{
u64 *waddr;
unsigned long flags;
int ret;
raw_spin_lock_irqsave(&patch_lock, flags);
waddr = patch_map(addr, FIX_TEXT_POKE0);
ret = copy_to_kernel_nofault(waddr, &val, sizeof(val));
patch_unmap(FIX_TEXT_POKE0);
raw_spin_unlock_irqrestore(&patch_lock, flags);
return ret;
}
int __kprobes aarch64_insn_patch_text_nosync(void *addr, u32 insn)
{
u32 *tp = addr;