| Message ID | 20241107111630.31068-1-mpe@ellerman.id.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | cfec8463d9a19ec043845525fe5fd675e59a8aab |
| Headers | show |
| Series | powerpc/ftrace: Fix ftrace bug with KASAN=y | expand |
On Thu, 07 Nov 2024 22:16:30 +1100, Michael Ellerman wrote: > Booting a KASAN=y kernel with the recently added ftrace out-of-line > support causes a warning at boot: > > ------------[ cut here ]------------ > Stub index overflow (1729 > 1728) > WARNING: CPU: 0 PID: 0 at arch/powerpc/kernel/trace/ftrace.c:209 ftrace_init_nop+0x408/0x444 > ... > NIP ftrace_init_nop+0x408/0x444 > LR ftrace_init_nop+0x404/0x444 > Call Trace: > ftrace_init_nop+0x404/0x444 (unreliable) > ftrace_process_locs+0x544/0x8a0 > ftrace_init+0xb4/0x22c > start_kernel+0x1dc/0x4d4 > start_here_common+0x1c/0x20 > ... > ftrace failed to modify > [<c0000000030beddc>] _sub_I_65535_1+0x8/0x3c > actual: 00:00:00:60 > Initializing ftrace call sites > ftrace record flags: 0 > (0) > expected tramp: c00000000008b418 > ------------[ cut here ]------------ > > [...] Applied to powerpc/next. [1/1] powerpc/ftrace: Fix ftrace bug with KASAN=y https://git.kernel.org/powerpc/c/cfec8463d9a19ec043845525fe5fd675e59a8aab cheers
diff --git a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh index 950a7778324b..bac186bdf64a 100755 --- a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh +++ b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh @@ -15,10 +15,11 @@ if [ -z "$is_64bit" ]; then RELOCATION=R_PPC_ADDR32 fi -num_ool_stubs_text=$($objdump -r -j __patchable_function_entries "$vmlinux_o" | - grep -v ".init.text" | grep -c "$RELOCATION") +num_ool_stubs_total=$($objdump -r -j __patchable_function_entries "$vmlinux_o" | + grep -c "$RELOCATION") num_ool_stubs_inittext=$($objdump -r -j __patchable_function_entries "$vmlinux_o" | - grep ".init.text" | grep -c "$RELOCATION") + grep -e ".init.text" -e ".text.startup" | grep -c "$RELOCATION") +num_ool_stubs_text=$((num_ool_stubs_total - num_ool_stubs_inittext)) if [ "$num_ool_stubs_text" -gt "$num_ool_stubs_text_builtin" ]; then num_ool_stubs_text_end=$((num_ool_stubs_text - num_ool_stubs_text_builtin))
Booting a KASAN=y kernel with the recently added ftrace out-of-line support causes a warning at boot: ------------[ cut here ]------------ Stub index overflow (1729 > 1728) WARNING: CPU: 0 PID: 0 at arch/powerpc/kernel/trace/ftrace.c:209 ftrace_init_nop+0x408/0x444 ... NIP ftrace_init_nop+0x408/0x444 LR ftrace_init_nop+0x404/0x444 Call Trace: ftrace_init_nop+0x404/0x444 (unreliable) ftrace_process_locs+0x544/0x8a0 ftrace_init+0xb4/0x22c start_kernel+0x1dc/0x4d4 start_here_common+0x1c/0x20 ... ftrace failed to modify [<c0000000030beddc>] _sub_I_65535_1+0x8/0x3c actual: 00:00:00:60 Initializing ftrace call sites ftrace record flags: 0 (0) expected tramp: c00000000008b418 ------------[ cut here ]------------ The function in question, _sub_I_65535_1 is some sort of trampoline generated for KASAN, and is in the .text.startup section. That section is part of INIT_TEXT, meaning is_kernel_inittext() returns true for it. But the script that determines how many out-of-line ftrace stubs are needed isn't doesn't consider .text.startup as inittext, leading to there not being enough space for the init stubs. Conversely the logic to calculate how many stubs are needed for the text section isn't filtering out the symbols in .text.startup and so ends up over counting. Fix both problems by calculating the total number of stubs first, then the number that count as inittext, and then subtract the latter from the former to get the count for the text section. Fixes: eec37961a56a ("powerpc64/ftrace: Move ftrace sequence out of line") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> --- arch/powerpc/tools/ftrace-gen-ool-stubs.sh | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)