From d2a28ad9fa7bf16761d070d8a3338375e1574b32 Mon Sep 17 00:00:00 2001 From: Russ Anderson Date: Fri, 24 Mar 2006 09:49:52 -0800 Subject: [IA64] MCA recovery: kernel context recovery table Memory errors encountered by user applications may surface when the CPU is running in kernel context. The current code will not attempt recovery if the MCA surfaces in kernel context (privilage mode 0). This patch adds a check for cases where the user initiated the load that surfaces in kernel interrupt code. An example is a user process lauching a load from memory and the data in memory had bad ECC. Before the bad data gets to the CPU register, and interrupt comes in. The code jumps to the IVT interrupt entry point and begins execution in kernel context. The process of saving the user registers (SAVE_REST) causes the bad data to be loaded into a CPU register, triggering the MCA. The MCA surfaces in kernel context, even though the load was initiated from user context. As suggested by David and Tony, this patch uses an exception table like approach, puting the tagged recovery addresses in a searchable table. One difference from the exception table is that MCAs do not surface in precise places (such as with a TLB miss), so instead of tagging specific instructions, address ranges are registers. A single macro is used to do the tagging, with the input parameter being the label of the starting address and the macro being the ending address. This limits clutter in the code. This patch only tags one spot, the interrupt ivt entry. Testing showed that spot to be a "heavy hitter" with MCAs surfacing while saving user registers. Other spots can be added as needed by adding a single macro. Signed-off-by: Russ Anderson (rja@sgi.com) Signed-off-by: Tony Luck --- arch/ia64/kernel/mca_drv.h | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'arch/ia64/kernel/mca_drv.h') diff --git a/arch/ia64/kernel/mca_drv.h b/arch/ia64/kernel/mca_drv.h index e2f6fa1e0ef..31a2e52bb16 100644 --- a/arch/ia64/kernel/mca_drv.h +++ b/arch/ia64/kernel/mca_drv.h @@ -111,3 +111,10 @@ typedef struct slidx_table { slidx_foreach_entry(__pos, &((slidx)->sec)) { __count++; }\ __count; }) +struct mca_table_entry { + int start_addr; /* location-relative starting address of MCA recoverable range */ + int end_addr; /* location-relative ending address of MCA recoverable range */ +}; + +extern const struct mca_table_entry *search_mca_tables (unsigned long addr); +extern int mca_recover_range(unsigned long); -- cgit v1.2.3