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ocall: add an example to show how to use OCALLs #64

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ocall: add an example to show how to use OCALLs #64

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HernanGatta
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@HernanGatta HernanGatta commented Sep 23, 2019 •
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This example shows how to use OCALLs to allow TA's to call back into their host. This example includes handling OCALL requests and responding to them by modifying INOUT and OUTPUT parameters.

Associated PR's: OP-TEE, OP-TEE Client, Linux.

Signed-off-by: Hernan Gatta hegatta@microsoft.com

This was referenced Sep 23, 2019
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@HernanGatta HernanGatta changed the title Generic RPC Example OCALL example Mar 19, 2020
This was referenced Mar 19, 2020
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etienne-lms
etienne-lms reviewed Mar 19, 2020
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suggest to move all printf info some DEBUG stderr path.

ocall/ta/ocall_ta.c Outdated
TEE_Param __unused params[TEE_NUM_PARAMS])
{
TEE_Result res;
uint32_t eorig;
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initialize to something meaningful and remove below empty line

ocall/ta/ocall_ta.c Outdated
if (param_types != expected_pt)
return TEE_ERROR_BAD_PARAMETERS;

res = TEE_InvokeCACommand(TEE_TIMEOUT_INFINITE, TA_OCALL_CA_CMD_TEST_1,
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minor: maybe prefer indent to (. (@jforissier, do we try to be strict on that?)

ocall/ta/ocall_ta.c Outdated
if (param_types != expected_pt)
return TEE_ERROR_BAD_PARAMETERS;

const uint32_t ocall_param_types = TEE_PARAM_TYPES(
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Define all local variables at block entry (here function entry).

ocall/host/main.c Outdated
printf("\tNo buffer\n");
return TEEC_ERROR_BAD_PARAMETERS;
}
printf("\tBuffer size: %zu\n", params[0].tmpref.size);
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fail if params[0].tmpref.size < strlen(msg) + 1;

ocall/host/main.c Outdated
}
printf("\tInput string: %s\n", (char *)params[0].tmpref.buffer);
printf("\tInput size: %zu\n", params[0].tmpref.size);
params[0].tmpref.size = strlen(msg) + 1;
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ditto on params[0].tmpref.size < strlen(msg) + 1

ocall/host/main.c Outdated
.u.ocall = &ocall_setting }
};
res = TEEC_OpenSessionEx(&ctx, &sess, &uuid, TEEC_LOGIN_PUBLIC, NULL,
NULL, &err_origin, settings, 1);
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minor: prefer

	TEEC_SessionSettingOcall ocall_setting = {
		.handler = ocall_handler,
		.context = &sess,
	};
	TEEC_SessionSetting settings = {
		.type = TEEC_SESSION_SETTING_OCALL,
		.u.ocall = &ocall_setting,
	};

	res = TEEC_OpenSessionEx(&ctx, &sess, &uuid, TEEC_LOGIN_PUBLIC, NULL,
				 NULL, &err_origin, &settings, 1);

Same comment for run_test_no_ecall_params() at line 139.

ocall/host/main.c Outdated
switch (commandId)
{
case TA_OCALL_CA_CMD_TEST_1:
printf("\tOK\n");
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check here paramType == all NONE as expected by the API.

ocall/ta/include/ocall_ta.h Outdated
#define TA_OCALL_CA_CMD_TEST_6 TA_OCALL_CMD_TEST_6
#define TA_OCALL_CA_CMD_TEST_7 TA_OCALL_CMD_TEST_7
#define TA_OCALL_CA_CMD_TEST_8 TA_OCALL_CMD_TEST_8
#define TA_OCALL_CA_CMD_TEST_9 TA_OCALL_CMD_TEST_9
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State somewhere what each test do.

ocall/host/main.c Outdated
printf("\tOK\n");
break;
case TA_OCALL_CA_CMD_TEST_2:
printf("\tInput values: %u, %u\n", params[0].value.a,
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check here paramType is VALUE_IN | NONE | NONE | NONE.

ocall/host/main.c Outdated
printf("\tOK\n");
break;
case TA_OCALL_CA_CMD_TEST_3:
printf("\tInput string: %s\n", (char *)params[0].tmpref.buffer);
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check paramType...

and same for the cases below.

@jenswi-linaro
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We may want to trim down this example a bit and add stuff to the regression tests instead.
But that can wait until we're done with the other parts.

@HernanGatta HernanGatta force-pushed the optee-generic-rpc-support branch 3 times, most recently from 8ea8897 to e14157e Compare April 16, 2020 03:19
@HernanGatta HernanGatta changed the title OCALL example ocall: add an example to show how to use OCALLs Jun 10, 2020
@HernanGatta HernanGatta force-pushed the optee-generic-rpc-support branch 2 times, most recently from f216caf to ea4362e Compare October 19, 2020 06:20
jforissier
jforissier reviewed Oct 19, 2020
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One spelling mistake below (we changed the type in the client library). Other than that, LGTM, it is a nice example.

Acked-by: Jerome Forissier <jerome@forissier.org>

ocall/host/main.c Outdated Show resolved Hide resolved
@HernanGatta
ocall: add an example to show how to use OCALLs
ae6247e 
The example first initializes a TEE context using the new settings API. It
then opens a session against the example OCALL TA via the new API to
configure sessions. The TA issues an OCALL during session open, which is
handled by the host. Thereafter, it performs a function invocation into the
OCALL TA to request that the latter call it back.

The OCALLs include value and memref parameters that are passed in multiple
directions. Via these parameters the TA and CA exchange information the
same way they would during a normal CA-to-TA function invocation.

Signed-off-by: Hernan Gatta <hegatta@microsoft.com>
Acked-by: Jerome Forissier <jerome@forissier.org>
@jenswi-linaro jenswi-linaro mentioned this pull request May 28, 2021
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