Message ID | 20170809132131.GB29494@leverpostej (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On Wed, Aug 09, 2017 at 02:21:31PM +0100, Mark Rutland wrote: > On Wed, Aug 09, 2017 at 11:07:35AM +0100, Catalin Marinas wrote: > > On Tue, Aug 08, 2017 at 05:10:51PM +0100, Mark Rutland wrote: > > > On Tue, Aug 08, 2017 at 04:58:53PM +0100, Catalin Marinas wrote: > > > > I'll pull arm64/exception-stack into for-next/core (I haven't got to the > > > > vmap-stack series yet). > > > > > > If you could hold off for a day, I'd like to make one final change and prevent > > > use of the final record's LR value, where FP is NULL, since that LR isn't > > > meaningful, and makes the backtrace look weird: > > > > > > [ 2785.650646] [<ffff000008082cb0>] el0_svc_naked+0x24/0x28 > > > [ 2785.656016] [<0000ffffaf717554>] 0xffffaf717554 > > > > > > Otherwise, I can do that as a fixup. > > > > I'll hold off, I haven't pushed the for-next/core branch out yet. > > I've pushed out an updated arm64/exception-stack branch. The HEAD should > be: > > 31e43ad3b74a5d7b ("arm64: unwind: remove sp from struct stackframe") > > That should have tvhe ASM_BUG() fix, and the below diff folded into the > pt_regs patch, to ensure that backtraces don't use user-controlled PCs > or idmap aliases of startup code. > > If you'd like, I can send the updated series as a v3. No need to, I'll just pull the branch. Thanks.
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 4ddb8d7..612a077 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -116,7 +116,11 @@ * time the exception was taken (in case we attempt to walk the call * stack later), chain it together with the stack frames. */ + .if \el == 0 + stp xzr, xzr, [sp, #S_STACKFRAME] + .else stp x29, x22, [sp, #S_STACKFRAME] + .endif add x29, sp, #S_STACKFRAME #ifdef CONFIG_ARM64_SW_TTBR0_PAN diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 973df7d..f9e4aac 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -362,6 +362,9 @@ __primary_switched: ret // to __primary_switch() 0: #endif + add sp, sp, #16 + mov x29, #0 + mov x30, #0 b start_kernel ENDPROC(__primary_switched) @@ -617,6 +620,7 @@ __secondary_switched: ldr x2, [x0, #CPU_BOOT_TASK] msr sp_el0, x2 mov x29, #0 + mov x30, #0 b secondary_start_kernel ENDPROC(__secondary_switched) diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c index 54f3463..35588ca 100644 --- a/arch/arm64/kernel/stacktrace.c +++ b/arch/arm64/kernel/stacktrace.c @@ -74,6 +74,15 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame) } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + /* + * Frames created upon entry from EL0 have NULL FP and PC values, so + * don't bother reporting these. Frames created by __noreturn functions + * might have a valid FP even if PC is bogus, so only terminate where + * both are NULL. + */ + if (!frame->fp && !frame->pc) + return -EINVAL; + return 0; }