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From 098dbe61246fd65ea5e3825d77afb31d52c43153 Mon Sep 17 00:00:00 2001
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From: Andreas Arnez <arnez@linux.vnet.ibm.com>
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Date: Fri, 12 Dec 2014 14:14:20 +0100
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Subject: [PATCH 7/9] gdbserver: Prevent stale/random values in register cache
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When fetch_inferior_registers does not update all registers, this
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patch assures that no stale register values remain in the register
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cache. On Linux platforms using the regsets interface, when one of
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the ptrace calls used for fetching the register values returns an
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error, this patch also avoids copying the random data returned from
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ptrace into the register cache. All unfetched registers are marked
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"unavailable" instead.
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gdb/gdbserver/ChangeLog:
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* linux-low.c (regsets_fetch_inferior_registers): Do not invoke
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the regset's store function when ptrace returned an error.
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* regcache.c (get_thread_regcache): Invalidate register cache
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before fetching inferior's registers.
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---
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gdb/gdbserver/ChangeLog | 7 +++++++
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gdb/gdbserver/linux-low.c | 11 ++++++-----
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gdb/gdbserver/regcache.c | 3 +++
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3 files changed, 16 insertions(+), 5 deletions(-)
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Index: gdb-7.6.1/gdb/gdbserver/linux-low.c
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===================================================================
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--- gdb-7.6.1.orig/gdb/gdbserver/linux-low.c
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+++ gdb-7.6.1/gdb/gdbserver/linux-low.c
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@@ -4080,8 +4080,6 @@ regsets_fetch_inferior_registers (struct
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/* If we get EIO on a regset, do not try it again for
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this process. */
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disabled_regsets[regset - target_regsets] = 1;
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- free (buf);
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- continue;
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}
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else
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{
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@@ -4091,9 +4089,12 @@ regsets_fetch_inferior_registers (struct
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perror (s);
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}
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}
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- else if (regset->type == GENERAL_REGS)
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- saw_general_regs = 1;
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- regset->store_function (regcache, buf);
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+ else
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+ {
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+ if (regset->type == GENERAL_REGS)
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+ saw_general_regs = 1;
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+ regset->store_function (regcache, buf);
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+ }
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regset ++;
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free (buf);
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}
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Index: gdb-7.6.1/gdb/gdbserver/regcache.c
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===================================================================
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--- gdb-7.6.1.orig/gdb/gdbserver/regcache.c
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+++ gdb-7.6.1/gdb/gdbserver/regcache.c
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@@ -47,6 +47,9 @@ get_thread_regcache (struct thread_info
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struct thread_info *saved_inferior = current_inferior;
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current_inferior = thread;
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+ /* Invalidate all registers, to prevent stale left-overs. */
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+ memset (regcache->register_status, REG_UNAVAILABLE,
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+ num_registers);
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fetch_inferior_registers (regcache, -1);
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current_inferior = saved_inferior;
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regcache->registers_valid = 1;
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