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| author | Ard Biesheuvel <ardb@kernel.org> | 2021-09-18 10:44:34 +0200 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2021-09-27 16:54:01 +0200 |
| commit | dfbdcda280eb762bae2184145cc0702932d41798 (patch) | |
| tree | 412a5d96995d2b0cb4d41409dd51476e3a7da8ea /scripts/gcc-plugins | |
| parent | Linux 5.15-rc1 (diff) | |
| download | linux-dfbdcda280eb762bae2184145cc0702932d41798.tar.xz linux-dfbdcda280eb762bae2184145cc0702932d41798.zip | |
gcc-plugins: arm-ssp: Prepare for THREAD_INFO_IN_TASK support
We will be enabling THREAD_INFO_IN_TASK support for ARM, which means
that we can no longer load the stack canary value by masking the stack
pointer and taking the copy that lives in thread_info. Instead, we will
be able to load it from the task_struct directly, by using the TPIDRURO
register which will hold the current task pointer when
THREAD_INFO_IN_TASK is in effect. This is much more straight-forward,
and allows us to declutter this code a bit while at it.
Note that this means that ARMv6 (non-v6K) SMP systems can no longer use
this feature, but those are quite rare to begin with, so this is a
reasonable trade off.
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
Diffstat (limited to 'scripts/gcc-plugins')
| -rw-r--r-- | scripts/gcc-plugins/arm_ssp_per_task_plugin.c | 27 |
1 files changed, 6 insertions, 21 deletions
diff --git a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c index 8c1af9bdcb1b..7328d037f975 100644 --- a/scripts/gcc-plugins/arm_ssp_per_task_plugin.c +++ b/scripts/gcc-plugins/arm_ssp_per_task_plugin.c @@ -4,7 +4,7 @@ __visible int plugin_is_GPL_compatible; -static unsigned int sp_mask, canary_offset; +static unsigned int canary_offset; static unsigned int arm_pertask_ssp_rtl_execute(void) { @@ -13,7 +13,7 @@ static unsigned int arm_pertask_ssp_rtl_execute(void) for (insn = get_insns(); insn; insn = NEXT_INSN(insn)) { const char *sym; rtx body; - rtx mask, masked_sp; + rtx current; /* * Find a SET insn involving a SYMBOL_REF to __stack_chk_guard @@ -30,19 +30,13 @@ static unsigned int arm_pertask_ssp_rtl_execute(void) /* * Replace the source of the SET insn with an expression that - * produces the address of the copy of the stack canary value - * stored in struct thread_info + * produces the address of the current task's stack canary value */ - mask = GEN_INT(sext_hwi(sp_mask, GET_MODE_PRECISION(Pmode))); - masked_sp = gen_reg_rtx(Pmode); + current = gen_reg_rtx(Pmode); - emit_insn_before(gen_rtx_set(masked_sp, - gen_rtx_AND(Pmode, - stack_pointer_rtx, - mask)), - insn); + emit_insn_before(gen_load_tp_hard(current), insn); - SET_SRC(body) = gen_rtx_PLUS(Pmode, masked_sp, + SET_SRC(body) = gen_rtx_PLUS(Pmode, current, GEN_INT(canary_offset)); } return 0; @@ -72,7 +66,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, const char * const plugin_name = plugin_info->base_name; const int argc = plugin_info->argc; const struct plugin_argument *argv = plugin_info->argv; - int tso = 0; int i; if (!plugin_default_version_check(version, &gcc_version)) { @@ -91,11 +84,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, return 1; } - if (!strcmp(argv[i].key, "tso")) { - tso = atoi(argv[i].value); - continue; - } - if (!strcmp(argv[i].key, "offset")) { canary_offset = atoi(argv[i].value); continue; @@ -105,9 +93,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, return 1; } - /* create the mask that produces the base of the stack */ - sp_mask = ~((1U << (12 + tso)) - 1); - PASS_INFO(arm_pertask_ssp_rtl, "expand", 1, PASS_POS_INSERT_AFTER); register_callback(plugin_info->base_name, PLUGIN_PASS_MANAGER_SETUP, |