diff options
| author | Christophe Leroy <christophe.leroy@csgroup.eu> | 2020-12-21 06:18:03 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-12-21 22:24:00 +1100 |
| commit | d5c243989fb0cb03c74d7340daca3b819f706ee7 (patch) | |
| tree | 951e03b4f41340c4faa01c0dd96b14bccd8236c7 /arch | |
| parent | 2eda7f11000646909a10298951c9defb2321b240 (diff) | |
powerpc/32: Fix vmap stack - Properly set r1 before activating MMU on syscall too
We need r1 to be properly set before activating MMU, otherwise any new
exception taken while saving registers into the stack in syscall
prologs will use the user stack, which is wrong and will even lockup
or crash when KUAP is selected.
Do that by switching the meaning of r11 and r1 until we have saved r1
to the stack: copy r1 into r11 and setup the new stack pointer in r1.
To avoid complicating and impacting all generic and specific prolog
code (and more), copy back r1 into r11 once r11 is save onto
the stack.
We could get rid of copying r1 back and forth at the cost of rewriting
everything to use r1 instead of r11 all the way when CONFIG_VMAP_STACK
is set, but the effort is probably not worth it for now.
Fixes: da7bb43ab9da ("powerpc/32: Fix vmap stack - Properly set r1 before activating MMU")
Cc: stable@vger.kernel.org # v5.10+
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a3d819d5c348cee9783a311d5d3f3ba9b48fd219.1608531452.git.christophe.leroy@csgroup.eu
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/head_32.h | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/powerpc/kernel/head_32.h b/arch/powerpc/kernel/head_32.h index 541664d95702..a2f72c966baf 100644 --- a/arch/powerpc/kernel/head_32.h +++ b/arch/powerpc/kernel/head_32.h @@ -121,18 +121,28 @@ #ifdef CONFIG_VMAP_STACK mfspr r11, SPRN_SRR0 mtctr r11 -#endif andi. r11, r9, MSR_PR - lwz r11,TASK_STACK-THREAD(r12) + mr r11, r1 + lwz r1,TASK_STACK-THREAD(r12) beq- 99f - addi r11, r11, THREAD_SIZE - INT_FRAME_SIZE -#ifdef CONFIG_VMAP_STACK + addi r1, r1, THREAD_SIZE - INT_FRAME_SIZE li r10, MSR_KERNEL & ~(MSR_IR | MSR_RI) /* can take DTLB miss */ mtmsr r10 isync + tovirt(r12, r12) + stw r11,GPR1(r1) + stw r11,0(r1) + mr r11, r1 +#else + andi. r11, r9, MSR_PR + lwz r11,TASK_STACK-THREAD(r12) + beq- 99f + addi r11, r11, THREAD_SIZE - INT_FRAME_SIZE + tophys(r11, r11) + stw r1,GPR1(r11) + stw r1,0(r11) + tovirt(r1, r11) /* set new kernel sp */ #endif - tovirt_vmstack r12, r12 - tophys_novmstack r11, r11 mflr r10 stw r10, _LINK(r11) #ifdef CONFIG_VMAP_STACK @@ -140,9 +150,6 @@ #else mfspr r10,SPRN_SRR0 #endif - stw r1,GPR1(r11) - stw r1,0(r11) - tovirt_novmstack r1, r11 /* set new kernel sp */ stw r10,_NIP(r11) mfcr r10 rlwinm r10,r10,0,4,2 /* Clear SO bit in CR */ |