From 2aa6ac03516d078cf0c35aaa273b5cd11ea9734c Mon Sep 17 00:00:00 2001 From: Florent Revest Date: Wed, 5 Apr 2023 20:02:46 +0200 Subject: arm64: ftrace: Add direct call support This builds up on the CALL_OPS work which extends the ftrace patchsite on arm64 with an ops pointer usable by the ftrace trampoline. This ops pointer is valid at all time. Indeed, it is either pointing to ftrace_list_ops or to the single ops which should be called from that patchsite. There are a few cases to distinguish: - If a direct call ops is the only one tracing a function: - If the direct called trampoline is within the reach of a BL instruction -> the ftrace patchsite jumps to the trampoline - Else -> the ftrace patchsite jumps to the ftrace_caller trampoline which reads the ops pointer in the patchsite and jumps to the direct call address stored in the ops - Else -> the ftrace patchsite jumps to the ftrace_caller trampoline and its ops literal points to ftrace_list_ops so it iterates over all registered ftrace ops, including the direct call ops and calls its call_direct_funcs handler which stores the direct called trampoline's address in the ftrace_regs and the ftrace_caller trampoline will return to that address instead of returning to the traced function Signed-off-by: Florent Revest Co-developed-by: Mark Rutland Signed-off-by: Mark Rutland Link: https://lore.kernel.org/r/20230405180250.2046566-2-revest@chromium.org Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/arm64/Kconfig') diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1023e896d46b..f3503d0cc1b8 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -185,6 +185,10 @@ config ARM64 select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS select HAVE_DYNAMIC_FTRACE + select HAVE_DYNAMIC_FTRACE_WITH_ARGS \ + if $(cc-option,-fpatchable-function-entry=2) + select HAVE_DYNAMIC_FTRACE_WITH_DIRECT_CALLS \ + if DYNAMIC_FTRACE_WITH_ARGS && DYNAMIC_FTRACE_WITH_CALL_OPS select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS \ if (DYNAMIC_FTRACE_WITH_ARGS && !CFI_CLANG && \ !CC_OPTIMIZE_FOR_SIZE) -- cgit v1.2.3