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

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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
Download Patch File Download Diff File Expand all files Collapse all files

24
arch/powerpc/lib/feature-fixups.c
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@@ -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" :