From 9f7132948dd9a08e020e6409ebe790d8fd9c6d5d Mon Sep 17 00:00:00 2001 From: Yao Qi Date: Wed, 27 Nov 2013 18:01:05 +0800 Subject: [PATCH] Delegate to target_ops->beneath for TARGET_OBJECT_RAW_MEMORY GDB on x86_64-linux is unable to disassemble on core-file target. $ ./gdb ./testsuite/gdb.base/corefile (gdb) core-file ./testsuite/gdb.base/corefile.core (gdb) disassemble main Dump of assembler code for function main: 0x0000000000400976 <+0>: Cannot access memory at address 0x400976 However, it works if we turn code-cache off. (gdb) set code-cache off (gdb) disassemble main,+4 Dump of assembler code from 0x400976 to 0x40097a: 0x0000000000400976 : push %rbp 0x0000000000400977 : mov %rsp,%rbp End of assembler dump. When code-cache is off, GDB will iterate target_ops from top to bottom and call to_xfer_partial. When current_target is "core", it will call to_xfer_partial of target "exec", which reads the contents for disassemble. However, dcache uses TARGET_OBJECT_RAW_MEMORY to read, but target_xfer_partial doesn't delegate requests to beneath for TARGET_OBJECT_RAW_MEMORY. This patch factors out the iteration from top to bottom to a new function, raw_memory_xfer_partial, and use it for TARGET_OBJECT_RAW_MEMORY. Regression tested on x86_64-linux. gdb: 2013-11-29 Yao Qi Pedro Alves * dcache.c (dcache_read_line): Use current_target.beneath instead of ¤t_target. * target.c (memory_xfer_partial_1): Factor code out to ... (raw_memory_xfer_partial): ... it. New function. (target_xfer_partial): Call raw_memory_xfer_partial if OBJECT is TARGET_OBJECT_RAW_MEMORY. --- gdb/ChangeLog | 10 +++++++++ gdb/dcache.c | 4 ++-- gdb/target.c | 67 +++++++++++++++++++++++++++++++++-------------------------- 3 files changed, 49 insertions(+), 32 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 6eef295..e86f5c3 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,13 @@ +2013-11-29 Yao Qi + Pedro Alves + + * dcache.c (dcache_read_line): Use current_target.beneath + instead of ¤t_target. + * target.c (memory_xfer_partial_1): Factor code out to ... + (raw_memory_xfer_partial): ... it. New function. + (target_xfer_partial): Call raw_memory_xfer_partial if OBJECT + is TARGET_OBJECT_RAW_MEMORY. + 2013-11-28 Doug Evans * breakpoint.h (gdbpy_breakpoint_object): Renamed from diff --git a/gdb/dcache.c b/gdb/dcache.c index ea2b732..12d1a4b 100644 --- a/gdb/dcache.c +++ b/gdb/dcache.c @@ -336,8 +336,8 @@ dcache_read_line (DCACHE *dcache, struct dcache_block *db) len -= reg_len; continue; } - - res = target_read (¤t_target, TARGET_OBJECT_RAW_MEMORY, + + res = target_read (current_target.beneath, TARGET_OBJECT_RAW_MEMORY, NULL, myaddr, memaddr, reg_len); if (res < reg_len) return 0; diff --git a/gdb/target.c b/gdb/target.c index cc6194b..6c72e70 100644 --- a/gdb/target.c +++ b/gdb/target.c @@ -1398,6 +1398,35 @@ memory_xfer_live_readonly_partial (struct target_ops *ops, return 0; } +/* Read memory from more than one valid target. A core file, for + instance, could have some of memory but delegate other bits to + the target below it. So, we must manually try all targets. */ + +static LONGEST +raw_memory_xfer_partial (struct target_ops *ops, void *readbuf, + const void *writebuf, ULONGEST memaddr, LONGEST len) +{ + LONGEST res; + + do + { + res = ops->to_xfer_partial (ops, TARGET_OBJECT_MEMORY, NULL, + readbuf, writebuf, memaddr, len); + if (res > 0) + break; + + /* We want to continue past core files to executables, but not + past a running target's memory. */ + if (ops->to_has_all_memory (ops)) + break; + + ops = ops->beneath; + } + while (ops != NULL); + + return res; +} + /* Perform a partial memory transfer. For docs see target.h, to_xfer_partial. */ @@ -1571,26 +1600,8 @@ memory_xfer_partial_1 (struct target_ops *ops, enum target_object object, to_xfer_partial is enough; if it doesn't recognize an object it will call the to_xfer_partial of the next target down. But for memory this won't do. Memory is the only target - object which can be read from more than one valid target. - A core file, for instance, could have some of memory but - delegate other bits to the target below it. So, we must - manually try all targets. */ - - do - { - res = ops->to_xfer_partial (ops, TARGET_OBJECT_MEMORY, NULL, - readbuf, writebuf, memaddr, reg_len); - if (res > 0) - break; - - /* We want to continue past core files to executables, but not - past a running target's memory. */ - if (ops->to_has_all_memory (ops)) - break; - - ops = ops->beneath; - } - while (ops != NULL); + object which can be read from more than one valid target. */ + res = raw_memory_xfer_partial (ops, readbuf, writebuf, memaddr, reg_len); /* Make sure the cache gets updated no matter what - if we are writing to the stack. Even if this write is not tagged as such, we still need @@ -1702,18 +1713,14 @@ target_xfer_partial (struct target_ops *ops, || object == TARGET_OBJECT_CODE_MEMORY) retval = memory_xfer_partial (ops, object, readbuf, writebuf, offset, len); - else + else if (object == TARGET_OBJECT_RAW_MEMORY) { - enum target_object raw_object = object; - - /* If this is a raw memory transfer, request the normal - memory object from other layers. */ - if (raw_object == TARGET_OBJECT_RAW_MEMORY) - raw_object = TARGET_OBJECT_MEMORY; - - retval = ops->to_xfer_partial (ops, raw_object, annex, readbuf, - writebuf, offset, len); + /* Request the normal memory object from other layers. */ + retval = raw_memory_xfer_partial (ops, readbuf, writebuf, offset, len); } + else + retval = ops->to_xfer_partial (ops, object, annex, readbuf, + writebuf, offset, len); if (targetdebug) { -- 2.7.4