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| author | Chris Metcalf <cmetcalf@tilera.com> | 2012-03-29 20:52:00 +0200 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2012-04-02 18:12:48 +0200 |
| commit | e17235382dbb05f70146e141e4b780fd069050dc (patch) | |
| tree | d4da45df23c48ac7e0e4f61821125174a39e436a | |
| parent | arch/tile: various bugs in stack backtracer (diff) | |
| download | linux-e17235382dbb05f70146e141e4b780fd069050dc.tar.xz linux-e17235382dbb05f70146e141e4b780fd069050dc.zip | |
arch/tile: work around a hardware issue with the return-address stack
In certain circumstances we need to do a bunch of jump-and-link
instructions to fill the hardware return-address stack with nonzero values.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
| -rw-r--r-- | arch/tile/include/asm/traps.h | 6 | ||||
| -rw-r--r-- | arch/tile/kernel/intvec_64.S | 12 | ||||
| -rw-r--r-- | arch/tile/kernel/traps.c | 6 |
3 files changed, 22 insertions, 2 deletions
diff --git a/arch/tile/include/asm/traps.h b/arch/tile/include/asm/traps.h index 5f20f920f932..e28c3df4176a 100644 --- a/arch/tile/include/asm/traps.h +++ b/arch/tile/include/asm/traps.h @@ -64,7 +64,11 @@ void do_breakpoint(struct pt_regs *, int fault_num); #ifdef __tilegx__ +/* kernel/single_step.c */ void gx_singlestep_handle(struct pt_regs *, int fault_num); + +/* kernel/intvec_64.S */ +void fill_ra_stack(void); #endif -#endif /* _ASM_TILE_SYSCALLS_H */ +#endif /* _ASM_TILE_TRAPS_H */ diff --git a/arch/tile/kernel/intvec_64.S b/arch/tile/kernel/intvec_64.S index 79c93e10ba27..2c181c864ef7 100644 --- a/arch/tile/kernel/intvec_64.S +++ b/arch/tile/kernel/intvec_64.S @@ -1156,6 +1156,18 @@ int_unalign: push_extra_callee_saves r0 j do_trap +/* Fill the return address stack with nonzero entries. */ +STD_ENTRY(fill_ra_stack) + { + move r0, lr + jal 1f + } +1: jal 2f +2: jal 3f +3: jal 4f +4: jrp r0 + STD_ENDPROC(fill_ra_stack) + /* Include .intrpt1 array of interrupt vectors */ .section ".intrpt1", "ax" diff --git a/arch/tile/kernel/traps.c b/arch/tile/kernel/traps.c index 2bb6602a1ee7..32acfd9e23d0 100644 --- a/arch/tile/kernel/traps.c +++ b/arch/tile/kernel/traps.c @@ -289,7 +289,10 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, address = regs->pc; break; #ifdef __tilegx__ - case INT_ILL_TRANS: + case INT_ILL_TRANS: { + /* Avoid a hardware erratum with the return address stack. */ + fill_ra_stack(); + signo = SIGSEGV; code = SEGV_MAPERR; if (reason & SPR_ILL_TRANS_REASON__I_STREAM_VA_RMASK) @@ -297,6 +300,7 @@ void __kprobes do_trap(struct pt_regs *regs, int fault_num, else address = 0; /* FIXME: GX: single-step for address */ break; + } #endif default: panic("Unexpected do_trap interrupt number %d", fault_num); |