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powerpc: Support prefixed instructions in alignment handler

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If a prefixed instruction results in an alignment exception, the
SRR1_PREFIXED bit is set. The handler attempts to emulate the
responsible instruction and then increment the NIP past it. Use
SRR1_PREFIXED to determine by how much the NIP should be incremented.

Prefixed instructions are not permitted to cross 64-byte boundaries. If
they do the alignment interrupt is invoked with SRR1 BOUNDARY bit set.
If this occurs send a SIGBUS to the offending process if in user mode.
If in kernel mode call bad_page_fault().

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alistair Popple <alistair@popple.id.au>
Link: https://lore.kernel.org/r/20200506034050.24806-29-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe
2020-05-06 13:40:48 +10:00
committed by Michael Ellerman
parent b4657f7650
commit 9409d2f9da
1 changed files with 18 additions and 1 deletions
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arch/powerpc/kernel/traps.c
+18 -1
View File
@@ -588,6 +588,8 @@ static inline int check_io_access(struct pt_regs *regs)
#define REASON_ILLEGAL (ESR_PIL | ESR_PUO)
#define REASON_PRIVILEGED ESR_PPR
#define REASON_TRAP ESR_PTR
#define REASON_PREFIXED 0
#define REASON_BOUNDARY 0
/* single-step stuff */
#define single_stepping(regs) (current->thread.debug.dbcr0 & DBCR0_IC)
@@ -602,12 +604,16 @@ static inline int check_io_access(struct pt_regs *regs)
#define REASON_ILLEGAL SRR1_PROGILL
#define REASON_PRIVILEGED SRR1_PROGPRIV
#define REASON_TRAP SRR1_PROGTRAP
#define REASON_PREFIXED SRR1_PREFIXED
#define REASON_BOUNDARY SRR1_BOUNDARY
#define single_stepping(regs) ((regs)->msr & MSR_SE)
#define clear_single_step(regs) ((regs)->msr &= ~MSR_SE)
#define clear_br_trace(regs) ((regs)->msr &= ~MSR_BE)
#endif
#define inst_length(reason) (((reason) & REASON_PREFIXED) ? 8 : 4)
#if defined(CONFIG_E500)
int machine_check_e500mc(struct pt_regs *regs)
{
@@ -1610,11 +1616,20 @@ void alignment_exception(struct pt_regs *regs)
{
enum ctx_state prev_state = exception_enter();
int sig, code, fixed = 0;
unsigned long reason;
/* We restore the interrupt state now */
if (!arch_irq_disabled_regs(regs))
local_irq_enable();
reason = get_reason(regs);
if (reason & REASON_BOUNDARY) {
sig = SIGBUS;
code = BUS_ADRALN;
goto bad;
}
if (tm_abort_check(regs, TM_CAUSE_ALIGNMENT | TM_CAUSE_PERSISTENT))
goto bail;
@@ -1623,7 +1638,8 @@ void alignment_exception(struct pt_regs *regs)
fixed = fix_alignment(regs);
if (fixed == 1) {
regs->nip += 4; /* skip over emulated instruction */
/* skip over emulated instruction */
regs->nip += inst_length(reason);
emulate_single_step(regs);
goto bail;
}
@@ -1636,6 +1652,7 @@ void alignment_exception(struct pt_regs *regs)
sig = SIGBUS;
code = BUS_ADRALN;
}
bad:
if (user_mode(regs))
_exception(sig, regs, code, regs->dar);
else