77 lines
2.8 KiB
Diff
77 lines
2.8 KiB
Diff
From 1e64a66f72c79874016e78a4672b85cdeb506b9f Mon Sep 17 00:00:00 2001
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From: Tom de Vries <tdevries@suse.de>
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Date: Tue, 4 Jun 2024 09:30:03 +0000
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Subject: [PATCH] [gdb/tdep] Fix gdb.base/watchpoint-running on
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{arm,ppc64le}-linux
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When running test-case gdb.base/watchpoint-running on ppc64le-linux, we get:
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...
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(gdb) watch global_var^M
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warning: Error when detecting the debug register interface. \
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Debug registers will be unavailable.^M
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Watchpoint 2: global_var^M
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(gdb) FAIL: $exp: all-stop: hardware: watch global_var
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FAIL: $exp: all-stop: hardware: watchpoint hit (timeout)
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...
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The problem is that ppc_linux_dreg_interface::detect fails to detect the
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hardware watchpoint interface, because the calls to ptrace return with errno
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set to ESRCH.
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This is a feature of ptrace: if a call is done while the tracee is not
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ptrace-stopped, it returns ESRCH.
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Indeed, in the test-case "watch global_var" is executed while the inferior is
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running, and that triggers the first call to ppc_linux_dreg_interface::detect.
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And because the detection failure is cached, subsequent attempts at setting
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hardware watchpoints will also fail, even if the tracee is ptrace-stopped.
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Fix this by calling target_can_use_hardware_watchpoint from
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linux_init_ptrace_procfs, which is called from both:
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- linux_nat_target::post_attach, and
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- linux_nat_target::post_startup_inferior.
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By fixing this here, we also fix the same problem for arm-linux.
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Tested on ppc64le-linux and arm-linux.
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PR tdep/31834
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Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31834
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PR tdep/31705
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Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31705
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(cherry picked from commit bbc92bfbf25ad42548100e31e491ed3c32fbfa3e)
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---
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gdb/linux-nat.c | 12 ++++++++++++
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1 file changed, 12 insertions(+)
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diff --git a/gdb/linux-nat.c b/gdb/linux-nat.c
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index c8991cc3da4..47d74d27e11 100644
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--- a/gdb/linux-nat.c
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+++ b/gdb/linux-nat.c
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@@ -385,6 +385,18 @@ linux_init_ptrace_procfs (pid_t pid, int attached)
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linux_ptrace_init_warnings ();
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linux_proc_init_warnings ();
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proc_mem_file_is_writable ();
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+
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+ /* Some targets (for instance ppc and arm) may call ptrace to answer a
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+ target_can_use_hardware_watchpoint query, and cache the result. However,
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+ the ptrace call will fail with errno ESRCH if the tracee is not
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+ ptrace-stopped, making the query fail. And if the caching mechanism does
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+ not disregard an ESRCH result, all subsequent queries will also fail.
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+ Call it now, where we known the tracee is ptrace-stopped.
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+
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+ Other targets (for instance aarch64) do the relevant ptrace call and
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+ caching in their implementation of post_attach and post_startup_inferior,
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+ in which case this call is expected to have no effect. */
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+ target_can_use_hardware_watchpoint (bp_hardware_watchpoint, 1, 0);
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}
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linux_nat_target::~linux_nat_target ()
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base-commit: a6800d9c8145f25001dd39afc3571e3350573e81
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--
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2.35.3
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