system/linux
system/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux synced 2024-10-03 09:48:02 +00:00
Code Issues Packages Projects Releases Wiki Activity

powerpc/64s: fix scv entry fallback flush vs interrupt

Browse source 
The L1D flush fallback functions are not recoverable vs interrupts,
yet the scv entry flush runs with MSR[EE]=1. This can result in a
timer (soft-NMI) or MCE or SRESET interrupt hitting here and overwriting
the EXRFI save area, which ends up corrupting userspace registers for
scv return.

Fix this by disabling RI and EE for the scv entry fallback flush.

Fixes: f79643787e ("powerpc/64s: flush L1D on kernel entry")
Cc: stable@vger.kernel.org # 5.9+ which also have flush L1D patch backport
Reported-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210111062408.287092-1-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-01-11 16:24:08 +10:00 committed by Michael Ellerman
parent dd3a44c06f
commit 08685be776
6 changed files with 71 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

13
arch/powerpc/include/asm/exception-64s.h
View file

@ -63,6 +63,12 @@
nop; \
nop;
#define SCV_ENTRY_FLUSH_SLOT \
SCV_ENTRY_FLUSH_FIXUP_SECTION; \
nop; \
nop; \
nop;
/*
* r10 must be free to use, r13 must be paca
*/
@ -70,6 +76,13 @@
STF_ENTRY_BARRIER_SLOT; \
ENTRY_FLUSH_SLOT
/*
* r10, ctr must be free to use, r13 must be paca
*/
#define SCV_INTERRUPT_TO_KERNEL \
STF_ENTRY_BARRIER_SLOT; \
SCV_ENTRY_FLUSH_SLOT
/*
* Macros for annotating the expected destination of (h)rfid
*

10
arch/powerpc/include/asm/feature-fixups.h
View file

@ -240,6 +240,14 @@ label##3: \
FTR_ENTRY_OFFSET 957b-958b; \
.popsection;
#define SCV_ENTRY_FLUSH_FIXUP_SECTION \
957: \
.pushsection __scv_entry_flush_fixup,"a"; \
.align 2; \
958: \
FTR_ENTRY_OFFSET 957b-958b; \
.popsection;
#define RFI_FLUSH_FIXUP_SECTION \
951: \
.pushsection __rfi_flush_fixup,"a"; \
@ -273,10 +281,12 @@ label##3: \
extern long stf_barrier_fallback;
extern long entry_flush_fallback;
extern long scv_entry_flush_fallback;
extern long __start___stf_entry_barrier_fixup, __stop___stf_entry_barrier_fixup;
extern long __start___stf_exit_barrier_fixup, __stop___stf_exit_barrier_fixup;
extern long __start___uaccess_flush_fixup, __stop___uaccess_flush_fixup;
extern long __start___entry_flush_fixup, __stop___entry_flush_fixup;
extern long __start___scv_entry_flush_fixup, __stop___scv_entry_flush_fixup;
extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;
extern long __start___barrier_nospec_fixup, __stop___barrier_nospec_fixup;
extern long __start__btb_flush_fixup, __stop__btb_flush_fixup;

2
arch/powerpc/kernel/entry_64.S
View file

@ -75,7 +75,7 @@ BEGIN_FTR_SECTION
bne .Ltabort_syscall
END_FTR_SECTION_IFSET(CPU_FTR_TM)
#endif
INTERRUPT_TO_KERNEL
SCV_INTERRUPT_TO_KERNEL
mr r10,r1
ld r1,PACAKSAVE(r13)
std r10,0(r1)

19
arch/powerpc/kernel/exceptions-64s.S
View file

@ -2993,6 +2993,25 @@ TRAMP_REAL_BEGIN(entry_flush_fallback)
ld r11,PACA_EXRFI+EX_R11(r13)
blr
/*
* The SCV entry flush happens with interrupts enabled, so it must disable
* to prevent EXRFI being clobbered by NMIs (e.g., soft_nmi_common). r10
* (containing LR) does not need to be preserved here because scv entry
* puts 0 in the pt_regs, CTR can be clobbered for the same reason.
*/
TRAMP_REAL_BEGIN(scv_entry_flush_fallback)
li r10,0
mtmsrd r10,1
lbz r10,PACAIRQHAPPENED(r13)
ori r10,r10,PACA_IRQ_HARD_DIS
stb r10,PACAIRQHAPPENED(r13)
std r11,PACA_EXRFI+EX_R11(r13)
L1D_DISPLACEMENT_FLUSH
ld r11,PACA_EXRFI+EX_R11(r13)
li r10,MSR_RI
mtmsrd r10,1
blr
TRAMP_REAL_BEGIN(rfi_flush_fallback)
SET_SCRATCH0(r13);
GET_PACA(r13);

7
arch/powerpc/kernel/vmlinux.lds.S
View file

@ -145,6 +145,13 @@ SECTIONS
__stop___entry_flush_fixup = .;
}
. = ALIGN(8);
__scv_entry_flush_fixup : AT(ADDR(__scv_entry_flush_fixup) - LOAD_OFFSET) {
__start___scv_entry_flush_fixup = .;
*(__scv_entry_flush_fixup)
__stop___scv_entry_flush_fixup = .;
}
. = ALIGN(8);
__stf_exit_barrier_fixup : AT(ADDR(__stf_exit_barrier_fixup) - LOAD_OFFSET) {
__start___stf_exit_barrier_fixup = .;

24
arch/powerpc/lib/feature-fixups.c
View file

@ -290,9 +290,6 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
long *start, *end;
int i;
start = PTRRELOC(&__start___entry_flush_fixup);
end = PTRRELOC(&__stop___entry_flush_fixup);
instrs[0] = 0x60000000; /* nop */
instrs[1] = 0x60000000; /* nop */
instrs[2] = 0x60000000; /* nop */
@ -312,6 +309,8 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
if (types & L1D_FLUSH_MTTRIG)
instrs[i++] = 0x7c12dba6; /* mtspr TRIG2,r0 (SPR #882) */
start = PTRRELOC(&__start___entry_flush_fixup);
end = PTRRELOC(&__stop___entry_flush_fixup);
for (i = 0; start < end; start++, i++) {
dest = (void *)start + *start;
@ -328,6 +327,25 @@ void do_entry_flush_fixups(enum l1d_flush_type types)
patch_instruction((struct ppc_inst *)(dest + 2), ppc_inst(instrs[2]));
}
start = PTRRELOC(&__start___scv_entry_flush_fixup);
end = PTRRELOC(&__stop___scv_entry_flush_fixup);
for (; start < end; start++, i++) {
dest = (void *)start + *start;
pr_devel("patching dest %lx\n", (unsigned long)dest);
patch_instruction((struct ppc_inst *)dest, ppc_inst(instrs[0]));
if (types == L1D_FLUSH_FALLBACK)
patch_branch((struct ppc_inst *)(dest + 1), (unsigned long)&scv_entry_flush_fallback,
BRANCH_SET_LINK);
else
patch_instruction((struct ppc_inst *)(dest + 1), ppc_inst(instrs[1]));
patch_instruction((struct ppc_inst *)(dest + 2), ppc_inst(instrs[2]));
}
printk(KERN_DEBUG "entry-flush: patched %d locations (%s flush)\n", i,
(types == L1D_FLUSH_NONE) ? "no" :
(types == L1D_FLUSH_FALLBACK) ? "fallback displacement" :