[PATCH] x86/unwind: fix guess unwinder regression
My attempt at fixing some KASAN false positive warnings was rather brain dead, and it broke the guess unwinder. With frame pointers disabled, /proc//stack is broken: # cat /proc/1/stack [] 0x Restore the code flow to more closely resemble its previous state, while still using READ_ONCE_NOCHECK macros to silence KASAN false positives. Fixes: c2d75e03d630 ("x86/unwind: Prevent KASAN false positive warnings in guess unwinder") Signed-off-by: Josh Poimboeuf--- arch/x86/kernel/unwind_guess.c | 9 ++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c index b80e8bf..22881dd 100644 --- a/arch/x86/kernel/unwind_guess.c +++ b/arch/x86/kernel/unwind_guess.c @@ -7,11 +7,13 @@ unsigned long unwind_get_return_address(struct unwind_state *state) { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + unsigned long addr; if (unwind_done(state)) return 0; + addr = READ_ONCE_NOCHECK(*state->sp); + return ftrace_graph_ret_addr(state->task, >graph_idx, addr, state->sp); } @@ -25,11 +27,12 @@ bool unwind_next_frame(struct unwind_state *state) return false; do { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + for (state->sp++; state->sp < info->end; state->sp++) { + unsigned long addr = READ_ONCE_NOCHECK(*state->sp); - for (state->sp++; state->sp < info->end; state->sp++) if (__kernel_text_address(addr)) return true; + } state->sp = info->next_sp; -- 2.7.4
[PATCH] x86/unwind: fix guess unwinder regression
My attempt at fixing some KASAN false positive warnings was rather brain dead, and it broke the guess unwinder. With frame pointers disabled, /proc//stack is broken: # cat /proc/1/stack [] 0x Restore the code flow to more closely resemble its previous state, while still using READ_ONCE_NOCHECK macros to silence KASAN false positives. Fixes: c2d75e03d630 ("x86/unwind: Prevent KASAN false positive warnings in guess unwinder") Signed-off-by: Josh Poimboeuf --- arch/x86/kernel/unwind_guess.c | 9 ++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/unwind_guess.c b/arch/x86/kernel/unwind_guess.c index b80e8bf..22881dd 100644 --- a/arch/x86/kernel/unwind_guess.c +++ b/arch/x86/kernel/unwind_guess.c @@ -7,11 +7,13 @@ unsigned long unwind_get_return_address(struct unwind_state *state) { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + unsigned long addr; if (unwind_done(state)) return 0; + addr = READ_ONCE_NOCHECK(*state->sp); + return ftrace_graph_ret_addr(state->task, >graph_idx, addr, state->sp); } @@ -25,11 +27,12 @@ bool unwind_next_frame(struct unwind_state *state) return false; do { - unsigned long addr = READ_ONCE_NOCHECK(*state->sp); + for (state->sp++; state->sp < info->end; state->sp++) { + unsigned long addr = READ_ONCE_NOCHECK(*state->sp); - for (state->sp++; state->sp < info->end; state->sp++) if (__kernel_text_address(addr)) return true; + } state->sp = info->next_sp; -- 2.7.4