5.10-stable patches

added patches:
	powerpc-64-signal-fix-regression-in-__kernel_sigtramp_rt64-semantics.patch

diff --git a/queue-5.10/powerpc-64-signal-fix-regression-in-__kernel_sigtramp_rt64-semantics.patch b/queue-5.10/powerpc-64-signal-fix-regression-in-__kernel_sigtramp_rt64-semantics.patch
new file mode 100644 (file)
index 0000000..a18c7f1
--- /dev/null
+++ b/queue-5.10/powerpc-64-signal-fix-regression-in-__kernel_sigtramp_rt64-semantics.patch
@@ -0,0 +1,87 @@
+From 24321ac668e452a4942598533d267805f291fdc9 Mon Sep 17 00:00:00 2001
+From: Raoni Fassina Firmino <raoni@linux.ibm.com>
+Date: Mon, 1 Feb 2021 17:05:05 -0300
+Subject: powerpc/64/signal: Fix regression in __kernel_sigtramp_rt64() semantics
+
+From: Raoni Fassina Firmino <raoni@linux.ibm.com>
+
+commit 24321ac668e452a4942598533d267805f291fdc9 upstream.
+
+Commit 0138ba5783ae ("powerpc/64/signal: Balance return predictor
+stack in signal trampoline") changed __kernel_sigtramp_rt64() VDSO and
+trampoline code, and introduced a regression in the way glibc's
+backtrace()[1] detects the signal-handler stack frame. Apart from the
+practical implications, __kernel_sigtramp_rt64() was a VDSO function
+with the semantics that it is a function you can call from userspace
+to end a signal handling. Now this semantics are no longer valid.
+
+I believe the aforementioned change affects all releases since 5.9.
+
+This patch tries to fix both the semantics and practical aspect of
+__kernel_sigtramp_rt64() returning it to the previous code, whilst
+keeping the intended behaviour of 0138ba5783ae by adding a new symbol
+to serve as the jump target from the kernel to the trampoline. Now the
+trampoline has two parts, a new entry point and the old return point.
+
+[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2021-January/223194.html
+
+Fixes: 0138ba5783ae ("powerpc/64/signal: Balance return predictor stack in signal trampoline")
+Cc: stable@vger.kernel.org # v5.9+
+Signed-off-by: Raoni Fassina Firmino <raoni@linux.ibm.com>
+Acked-by: Nicholas Piggin <npiggin@gmail.com>
+[mpe: Minor tweaks to change log formatting, add stable tag]
+Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
+Link: https://lore.kernel.org/r/20210201200505.iz46ubcizipnkcxe@work-tp
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/powerpc/kernel/vdso.c              |    2 +-
+ arch/powerpc/kernel/vdso64/sigtramp.S   |   11 ++++++++++-
+ arch/powerpc/kernel/vdso64/vdso64.lds.S |    1 +
+ 3 files changed, 12 insertions(+), 2 deletions(-)
+
+--- a/arch/powerpc/kernel/vdso.c
++++ b/arch/powerpc/kernel/vdso.c
+@@ -475,7 +475,7 @@ static __init void vdso_setup_trampoline
+        */
+ 
+ #ifdef CONFIG_PPC64
+-      vdso64_rt_sigtramp = find_function64(v64, "__kernel_sigtramp_rt64");
++      vdso64_rt_sigtramp = find_function64(v64, "__kernel_start_sigtramp_rt64");
+ #endif
+       vdso32_sigtramp    = find_function32(v32, "__kernel_sigtramp32");
+       vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32");
+--- a/arch/powerpc/kernel/vdso64/sigtramp.S
++++ b/arch/powerpc/kernel/vdso64/sigtramp.S
+@@ -15,11 +15,20 @@
+ 
+       .text
+ 
++/*
++ * __kernel_start_sigtramp_rt64 and __kernel_sigtramp_rt64 together
++ * are one function split in two parts. The kernel jumps to the former
++ * and the signal handler indirectly (by blr) returns to the latter.
++ * __kernel_sigtramp_rt64 needs to point to the return address so
++ * glibc can correctly identify the trampoline stack frame.
++ */
+       .balign 8
+       .balign IFETCH_ALIGN_BYTES
+-V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
++V_FUNCTION_BEGIN(__kernel_start_sigtramp_rt64)
+ .Lsigrt_start:
+       bctrl   /* call the handler */
++V_FUNCTION_END(__kernel_start_sigtramp_rt64)
++V_FUNCTION_BEGIN(__kernel_sigtramp_rt64)
+       addi    r1, r1, __SIGNAL_FRAMESIZE
+       li      r0,__NR_rt_sigreturn
+       sc
+--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
++++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
+@@ -150,6 +150,7 @@ VERSION
+               __kernel_get_tbfreq;
+               __kernel_sync_dicache;
+               __kernel_sync_dicache_p5;
++              __kernel_start_sigtramp_rt64;
+               __kernel_sigtramp_rt64;
+               __kernel_getcpu;
+               __kernel_time;

diff --git a/queue-5.10/series b/queue-5.10/series
index 613ee3e80fc16b3c22ccff82369a07c70cf0e6ac..6ec9734038644db62e18e876e179b50d078e18c6 100644 (file)
--- a/queue-5.10/series
+++ b/queue-5.10/series
@@ -15,3 +15,4 @@ io_uring-fix-sqo-ownership-false-positive-warning.patch
 io_uring-reinforce-cancel-on-flush-during-exit.patch
 io_uring-drop-mm-files-between-task_work_submit.patch
 gpiolib-cdev-clear-debounce-period-if-line-set-to-output.patch
+powerpc-64-signal-fix-regression-in-__kernel_sigtramp_rt64-semantics.patch